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MICROBIOLOGY FOR THE UNINITIATED – PART 1: WHAT ARE MICROORGANISMS AND WHY SHOULD WE CARE?

Microorganisms – a) virus; b) bacteria; c) archaea; d) yeast; d) mold.

Each year, on the first morning of STLE’s Metalworking Fluid Management Certificate Training Course, I ask attendees about their backgrounds. Invariably, the majority have at least undergraduate degrees in chemistry, engineering, or chemical engineering. However, of the more than 600 people who have taken the course since 2004, fewer than 50 have had a microbiology course.

Globally, biodeterioration – damage that organisms cause – has been estimated to range between $100 billion and $500 billion annually. Of this, 70 % to 80 % of biodeterioration damage is caused by microorganisms. Add to this an estimated $1 trillion cost due to infectious disease. On the flipside, biotechnology is a $500 billion industry that is based on microbiology. Just considering the economic impact microbe have on our lives, one might reasonably ask why so few people have received the most rudimentary education about microbes. Perhaps it’s the six syllables in microorganism (mic-ro-org-an-is-m) and microbiology that make the topic so intimidating. Still, given the role of microbes in disease, nature’s primary cycles, and biotechnology, one might think that every high school graduate would have learned something about microbiology. In this post and the next several to follow, I will do my best to demystify microbiology.

In this month’s article and those that follow, I’ll offer a very superficial overview of microbiology from an ecological and industrial perspective. There are numerous, excellent introductory microbiology textbooks. I don’t intend to provide any level of detail approaching that of a microbiology textbook. My intention is to help non-technical readers gain a fundamental appreciation for how microbes can affect their lives and their businesses.

Definition

Microorganisms (micro – meaning: small + organism – meaning: something having many related parts that function together as a whole) are living things that are too small to be seen by the naked eye. Microbiologists agree that bacteria, archaea, and some fungi (yeasts and molds) are microorganisms.

The status of virus is still a matter of debate. Viruses are essentially genetic material packaged in a protein coat. They don’t perform most of the functions that are used to define living beings. Thus most microbiologists do not consider viruses to be life forms. However, viruses reproduce by infecting cells and hijacking their victim’s (host’s) metabolic machinery to reproduce. Consequently, some microbiologists believe viruses should be classified as living things. Image (a) in the title figure shows a tobacco mosaic virus (TMV). The TMV virus is structurally complex, regardless of how we classify it. I included a virus in the in the figure because there are research groups investigating the use of viruses to control microbial contamination in industrial systems. I’ll return to this topic in a future post.

Abundance

One recent study, illustrated in Figure 1, estimated that microorganisms represent ~17% of Earth’s total biomass (estimated total biomass 550 gigatons of carbon – Gt C; 1Gt = 10⁹ tons – and bacterial biomass ≈70 Gt)¹. The contribution of bacteria to the Earth’s biomass is second only to that of plants. Microorganism biomass – including that of archaea, bacteria, fungi, protists, and viruses – account for ~93Gt.

A microbiome is the population of all microbes living in a specific ecosystem (fuel tank, cooling tower, human gut, etc.). Researchers investigating the human microbiome have estimated that the average human body has between 1x to 10x as many microbial cells as human cells. Moreover, it has been discovered that tissues, long thought to be microbe-free, have specific microbiomes that are likely to be essential for healthy tissue function (we have known about skin and gut microbes for nearly 170 years, but finding microbiomes specific to nearly every human tissue type (organs, muscle, etc.) was a surprise. Investigators have only scratched the surface of human microbiome research. We have little idea of how microbes interact with human cells and what roles they play in maintaining good health.

Fig 1. Relative abundance of Earth’s lifeforms, in Gt.

Diversity

As I will explain in future articles, the microbial world is remarkably diverse. The number of different types of bacteria has been estimated to range from hundreds of thousands to tens of millions, of which only a fraction of a percent has been identified.

I’ll discuss why below. Despite their central importance to life as we know it, even the most rudimentary discussion of microorganisms or microbiology (i.e., the study of microorganisms) is rarely included in high school or university curricula.

A Brief History

Tree of Life

Microbes were the first organisms to exist on earth. Our current understanding is that Earth formed 4.6 billion (4,600,000,000) years ago. There is evidence that the first microbes came into existence approximately 3.5 to 3.8 billion years ago (the fossil record indicates that mammals appeared 65 million years ago, and humans showed up a mere 315,000 years ago). Figure 3 illustrates the life on Earth timeline. The bar illustrating Earth’s age is 5 inches (in) long and the one for microorganisms is 4.1 in long. By comparison, the one for plants is 0.2 in and the one for humans is 0.000003 in – too thin to see! Thus, for more than 3 billion years, microbes were the only life forms on Earth.

If we visualize life as a tree, the organisms began to diversify genetically approximately 3.2 to 3.5 billion years ago (Figure 3). This was the time of the last universal common ancestor – LUCA – of all cellular organisms, starting with the bacteria and (thus far) culminating in humans. Before the microbes now classified as members of the kingdom Archaea were discovered near ocean floor, thermal vents in the Marianas Trench, in 1960, the tree of life was thought to have three Kingdoms: Monera (Prokaryota – all single cell organisms that do not have a nucleus or other membrane-bound internal bodies, Protista – all single cell organisms with a nucleus and other membrane-bound bodies, and Eukaryota – all multicellular organisms). As depicted in Figure 3a, in the 1960s through 1990s, Archaea were classified as Archaebacteria. When viewed through a microscope, they appeared to be bacteria. Believing that conditions around Marianas Trench thermal vents was similar to those of primordial Earth, microbiologists initially assumed that Archaea were more ancient than true bacteria – Eubacteriales. As genetic tools became available in the early 1990s, it became apparent that a) Eubacteriales are more ancient than Archaea (Figure 3b), and b) the Archaea are sufficiently distinct genetically to be its own phylogenic Kingdom (phylogenics – the study of evolutionary development and diversification of a species or group of organisms). When Figure 3a was created, fungi were thought to be much more ancient than plants or animals. As Figure 3b illustrates, the phylogenetic tree of life branched off to fungi, plants, and animals a mere half-billion years ago. Thus, fungi are more closely related to us than they are to bacteria.

Fig 2. Timelines – microorganisms appeared approximately 1 billion years after Earth was formed and more than 3 billion years before the first plants appeared. Brown bar – Earth’s age; blue bar microorganisms’ age; green bar – time since plants first appeared; yellow bar – time since first animals appeared; purple bar (invisibly narrow line) – time since humans appeared.

Fig 3. Phylogenic trees – a) Tree from mid-1960s depicting Archaebacteria as being more ancient than Eubacteria; b) Woese et al. (1990²) phylogenic tree showing three Kingdoms – Bacteria, Archaea, and Eucarya. Line segment lengths are based on genetic differences (longer lines indicate greater differences). The initial split at bottom center is LUCA.

Genomic testing has been a cottage industry since the late 1990s. A recent diagram (Figure 4) is based on the genomics of 2.3 million different species, from bacteria to humans, illustrates how complex the Tree has become (or as some authors note, the Tree now looks more like a Bush).

Fig 4. 2015 Tree of Life based on genetic data from 2.3 species.³

Human Awareness

Humans have been using microbes from time immemorial. We have been fermenting grains and grapes, and making cheeses, for as long as we have been cultivating plants or maintaining livestock. Modern microbiology dates from 1665, when Roert Hooke published Micrographia: or some Physiological Descriptions of Minute Bodies made by Magnifying Glasses with Observations and Inquiries Thereupon. A decade later, Antonie van Leeuwenhoek published his observations. Hooke and van Leeuwenhoek had each constructed microscopes through which they observed and created sketches of microorganisms (Figures 5a and 5b). However, it took another 200 years before Louis Pasteur and Robert Koch demonstrated that microbes were living beings and were responsible for fermentation, disease, and spoilage.

Fig 5. First microscopes – a) replica of Robert Hook’s microscope; b) replica of Antonie van Leeuwenhoek’s microscope.

Louis Pasteur conducted experiments to disprove the theory of spontaneous generation (belief that microbes developed from inanimate components of the materials which they caused to rot) and prove the germ theory of disease (i.e., that microorganisms did not form spontaneously and that they caused disease, biodeterioration, and were the agents responsible for fermentation). Pasture used goosenecked flasks (Figure 6) to demonstrate that microbes did not proliferate (multiply) in broth boiled in the flasks but did in identical flasks that contained unboiled broth. Proliferation also occurred when Pasteur intentionally permitted boiled broth to be exposed to microbially contaminated air (i.e., either by breaking off the gooseneck or tipping the flask). The gooseneck shape allowed air but not microbes to enter the flasks. These experiments led to Pasteur’s development of the pasteurization – the process of heating substances at temperatures sufficient to disinfect but not degrade them.

Fig 6. Drawing of Louis Pasteur’s gooseneck flask used to disprove spontaneous generation theory.

While Pasteur was focusing on fermentation microbiology, Robert Koch demonstrated the unequivocal relationship between microbes and disease. Koch demonstrated that the disease, anthrax was caused by the spore forming bacterium, Bacillus anthracis. He also developed the first solid growth media so that he could isolate pure cultures from colonies (Figure 7, zone 5). Pasteur’s and Koch’s research launched the modern age of microbiological research.

Fig 7. Obtaining a pure (single type of bacterium) culture by the streak plate method – a) specimen is collected using a sterilized inoculating loop; b) successively, initial specimen is deposited onto solid nutrient medium using a back-and forth motion (1), inoculating loop is heat sterilized, cooled, and oved across initial inoculation zone (2). This dilutes the sample. The final iteration (5) typically produces individual colonies after the inoculated plate has been incubated.

As now, much of the research performed during the late 19th century was focused on the relationship between microbes and disease. However, Sergei Winogradsky became the father of microbial ecology. Based on his pioneering research on sulfur metabolism in the late 1880s, Winogradsky developed the theory of biogeochemical cycles. This theory states that elements like sulfur, carbon, nitrogen, and phosphorous cycle through nature (Figure 8). These cycles are primarily mediated by microbial activity. The first paper describing gasoline deterioration by microbes was published in 1895. Starting in the 1920s, considerable effort was focused on oilfield damage caused by microorganisms. This research included the first studies on what was originally called microbially induced corrosion (MIC – now microbiologically influenced corrosion – see MICROBIOLOGICALLY INFLUENCED CORROSION – Biodeterioration Control Associations, Inc. (biodeterioration-control.com)). However, the term biodeterioration was not coined until 1965, when H. J. Hueck offered the definition: “any undesirable change in the properties of a material caused by the vital activities of organisms.”⁴

Fig 8. Biogeochemical cycles – this illustration provided a simplified depiction of how carbon (C), nitrogen (N), phosphorous (P), and sulfur (S) cycle through nature.

In my seminars on the topic I explain that biodeterioration and bioremediation are two sides of the same biodegradation coin (Figure 9). As Winogradsky observed, microbes drive biogeochemical cycles. These cycles occur regardless of human intent. When we want biodegradation to occur, we call it bioremediation. When microbial activity causes changes, we’d prefer to prevent, we call it biodeterioration (see https://biodeterioration-control.com/2018/03/).

Fig 9. Like the obverse (front) and reverse (back) sides of this 2000 Sacagawea U.S. dollar coin, bioremediation and biodeterioration are flips sides of biodegradation.

Summary

Microbes play invaluable roles in our lives. Our bodies would not function without the microbes that make up he human microbiome. Fewer than 2,000 pathogenic microbes have been identified among the tens of thousands that have been identified and the millions of different types of microbes that exist in nature. Microbes mediate nutrient cycles. This cycling conserves essential nutrients and prevents wastes from accumulating. Biodegradation includes all processes that breakdown organic substances. On one hand, biodegradation is the foundational element of a $0.5 trillion biotechnology industry. On the other, biodeterioration and infectious disease cost $1.5 trillion per year. We are part of the microbial world. To me, that seems like an excellent reason why everyone should have a basic understanding of microbiology.

For more information about fuel system condition monitoring and predictive maintenance, contact me at fredp@biodeterioration-control.com.

¹ Bar-On, Y.M, Phillips, R., Milo, R., 2018. The biomass distribution on Earth. Proc Natl Acad Sci U S A., 115(25):6506-6511. https://pubmed.ncbi.nlm.nih.gov/29784790/.
² Woese, C. R., Kandler, O., Wheelis M.L., 1990. Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya. Proceedings of the National Academy of Sciences of the United States of America. 87 (12): 4576–9. https://doi.org/10.1073/pnas.87.12.4576.
³ Hinchliff, C. et al., 2015. Synthesis of Phylogeny and Taxonomy Into a Comprehensive Tree of Life. Proceedings of the National Academy of Sciences https://www.pnas.org/doi/full/10.1073/pnas.1423041112.
⁴ Hueck, H.J., 1965. The Biodeterioration of Materials as a Part of Hylobiology. Material und Organismen, 1, 5-34.

WHAT’S IN A NAME – ARE BIOCIDE-FREE METALWORKING FLUIDS LESS TOXIC THAN THOSE FORMULATED WITH BIOCIDES?

One of the more famous quotes from William Shakespeare’s play, Romeo and Juliet.

Language Matters

In this month’s article I’ll address the use of what I call unregistered microbicides.

Over the course of the past several decades, industry and regulators have taken increasingly jaundiced views of chemical substances variously known as antimicrobial pesticides, biocidal substances, biocides, biocidal products, and microbicides. What are these substances? The EU’s Biocidal Products Regulation (BPR – Regulation (EU) No 528/2012 of the European Parliament and of the Council of 22 May 2012) Article 3, 1 (a) offers this definition:

— any substance or mixture, in the form in which it is supplied to the user, consisting of, containing or generating one or more active substances, with the intention of destroying, deterring, rendering harmless, preventing the action of, or otherwise exerting a controlling effect on, any harmful organism by any means other than mere physical or mechanical action,

— any substance or mixture, generated from substances or mixtures which do not themselves fall under the first indent, to be used with the intention of destroying, deterring, rendering harmless, preventing the action of, or otherwise exerting a controlling effect on, any harmful organism by any means other than mere physical or mechanical action.

A treated article that has a primary biocidal function shall be considered a biocidal product.

I’ve highlighted key words in the BPR definition because one response from industry has been to replace products that are registered as microbicides with alternative chemistries that do are not registered. They then promote their finish goods as being “biocide free.”

I pose this question:
Is it legitimate to make a biocide-free claim if a substance is used to control microbial contamination in a formulated product although it does not have an antimicrobial pesticide registration?

Non-biocidal additives in water-miscible metalwork fluids (MWF)

There are three groups of products related to MWF biodeterioration resistance – bioresistant, biostatic, and adjuvant additives.

Bioresistant additives

Bioresistant (recalcitrant) additives are chemistries that are difficult for microbes to use as food. As illustrated in Figure 1, their concentration in a fluid is unaffected by the fluid’s bioburden.

Fig 1. Bioresistant MWF additive – additive concentration is unaffected by microbial load (bioburden).¹

Biostatic additives

In contrast to bioresistant additives, for which there appears to be no interaction between microbes and the additive, biostatic additives contribute to the MWF formulation’s ability to resist microbial growth. Figure 2a shows that when a biostatic MWF is inoculated with microbes, they do not proliferate (i.e., the biobuden does not increase). However (Figure 2b), if a biostatic additive is added to a heavily contaminated MWF, it has no effect on the biobuden.

Fig 2. Biostatic MWF additive – a) When microbes are added to biostatic MWF formulation, they do not proliferate; b) when a biostatic additive is added to a heavily contaminated MWF, it has no impact on the bioburden.

Adjuvants

Additives that have no direct impact on microbial contamination in MWF (Figure 3a), but which improve the performance of microbicides are called adjuvants. Figure 3 illustrates this concept. Microbicides can kill off microbes (Figures 3b and 3c, red line), prevent microbes from proliferating (Figure 3d), or do both.

Fig 3. Adjuvant MWF additive impact on biomass – a) adjuvant without microbicide; b) microbicide speed of kill without adjuvant; c) microbicide speed of kill with adjuvant; d) microbial proliferation in MWF formulated with microbicide (red line) and microbicide plus adjuvant (purple line).

Similarly, an adjuvant can increase a microbicide’s speed of kill (Figure 3c, purple line), prolong the duration of its effectiveness against repeated challenges (Figure 3d, purple line) or both. The red arrows in Figure 3d indicate weekly inoculation of the test MWF with a microbial challenge population per ASTM Practice E2275.

Unregistered, microbicidal additives in water-miscible MWF

A key word in BPR’s biocide definition is intention. With this word, BPR’s definition shifts from an objective perspective – if a substance has a controlling effect on microbes, it is a microbicide – to a subjective perspective – only if it was intended for a substance to have a controlling effect on microbes is that substance subject to BPR registration. The U.S. Federal Insecticide, Rodenticide and Pesticide Act (FIFRA) has similar language (Sec. 2 [17 U.S.C. 136 (u)). The challenge is in reaching consensus on the meaning intention regarding the use of MWF functional additives.

Functional additives

In the MWF sector, a functional additive is a chemical substance that provides one or more performance properties to the fished formulation. Typical functional additive performance properties include:

Corrosion inhibition
Coupling – additives that provide chemical bonds between dissimilar substances (e.g., base oils and polar molecules)
Emulsion stabilization
Foam inhibition
Lubricity
Microbicidal activity
pH control (buffering)

Products used in several of these functional categories also impact microbial contamination. All chemicals sold for use in technical applications Europe must be registered in accordance with Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH – Regulation (EC) No 1907/2006 of the European Parliament and of the Council of 18 December 2006). In the early and mid-1990s, I was hopeful that REACH would the toxicity data required for all industrial chemicals would be similar. This would have closed the cost gap associated with obtaining the toxicity data needed for microbicide registration versus that needed for non-microbicidal substances. However, requiring a full toxicological test package for each of the millions of industrial chemicals was determined to be prohibitively expensive. Additionally, the time and laboratory facilities required to test all industrial chemicals rendered the concept untenable. Consequently, although some toxicological data are required to support product registrations under REACH, substantially more is needed for product registration under BPR. This creates a grey zone.

What is the difference between a registered and an unregistered microbicide?

Per the definition I quoted in the opening paragraph, a registered microbicide is an active substance (ingredient) or formulated product intentionally used to control microbial contamination and approved for such use by the cognizant regulatory agency (e.g., the European Chemical Agency’s – ECHA’s – Biocidal Products Committee, and the U.S. EPA’s Office of Pesticide Programs).

There is no consensus on definition of an unregistered microbicide. Nor is there consensus about the concept of intention. There is no universally agreed upon demarcation between a non-biocidal additive that also affects microbial contamination and one that has some level of non-biocidal activity (e.g., corrosion inhibition) but primarily inhibits microbial growth. To further complicate matters, there are numerous technical grade substances that are substantially more toxic than biocidal products. Moreover, there are registered microbicides that have non-biocidal applications. For example, hexahydro-1,3,5-tris(hydroxyethyl)-s-triazine (HTHT – CAS 4719-04-4) is registered as a MWF microbicide under the BPR, FIFRA and other nations’ pesticide regulations. However, it is also an effective sulfide scavenger used to scrub sulfide from gas generate during petroleum refining. When the product is sold for antimicrobial purposes, it has a pesticide label. When it is sold as a sulfide scavenger it has a technical chemical, it has a substantially less informative label – there is no intention of antimicrobial activity when HTHT is used as a sulfide scavenger.

For decades, I have argued the following:

If an additive demonstrates one or more, better than average, non-biocidal functional properties – regardless of its antimicrobial properties – it need not be registered as a biocidal substance unless biocidal claims are made.
If an additive does not demonstrate one or more, better than average, non-biocidal functional properties, and demonstrates antimicrobial performance, it should be registered as a biocidal substance.

Case study – Dicyclohexylamine

Dicyclohexylamine (DCHA, CAS 101-83-7) is a secondary amine that has been used in MWF formulations for more than two decades. As a chemical group, amines have several performance properties, the most common of which are:

Corrosion inhibition
Emulsion stabilization
pH control (buffering)

However, performance in each category varies substantially among amines. When DCHA has been tested for its corrosion inhibition, emulsion stabilization, or pH control performance, it has not compared favorably relative to other amines. Figure 4 is a plot of DCHA’s antimicrobial performance in a MWF. Testing was performed per ASTM Practice E2275. As Figure 4 illustrates, in a MWF that contained DCHA at 3,000 mg kg^-1 (ppm), the challenge population fell to below detection levels (BDL) and remained BDL for the duration of the eight-week study.

DCHA is an example of a chemical that has demonstrated antimicrobial performance properties, is represented as having typical amine performance properties (although with no supporting data) and is used in MWF formulations. It is a prime example of an additive that does not demonstrate one or more, better than average, non-biocidal functional properties, and demonstrates antimicrobial performance – i.e., an unregistered microbicide.

Fig 4. ASTM Practice E2275 test results – MWF formulated with DCHA at 3,000 mg kg^-1.

Now compare DCHA’s toxicity profile with that of HTHT. The data in Table 1 are taken from the products’ respective Safety Data Sheets (SDS). Per the SDS data, DCHA’s acute oral toxicity is >5x that of HTHT and its acute dermal toxicity is 10x that of HTHT. Moreover, DCHA’s ecotoxicity is greater than that of HTHT and its biodegradability is less than that of HTHT. Consequently, although MWF formulated with DCHA can claim to be biocide-free (they do not contain appropriately registered microbicides), they are potentially more toxic and less environmentally acceptable.

Table 1. Product SDS toxicity profile comparison – DCHA and HTHT.

Are there regulatory or liability issues?

This is an issue for regulators and lawyers. I am neither. However, there are precedents that suggest MWF compounders who use putative performance additives that do not actually demonstrate one or more, better than average, non-biocidal functional properties, but do demonstrate antimicrobial performance have exposure on both counts. There have been class-action lawsuits in which the plaintiffs have claimed adverse health effects caused by MWF exposure and in which MWF compounders have been listed as defendants. One can only speculate on the impact of formulations with unregistered microbicides on the ability of formulators to create a credible defense against adverse health complaints.

From a regulatory perspective, the issue is what claims are made. Some years ago, a food grade lubricant compounder formulated some of their products with PARABENs (para-hydroxy benzoic acid esters). Although PARABENs are commonly used as food and cosmetic preservatives, they are not registered as industrial microbicides. The compounder promoted the antimicrobial activity of their food grade lubricant. In doing so, they violated two laws. They used unregistered biocidal products as microbicides in the lubricant. They made pesticidal claims for their lubricant, although the product did not have a U.S. EPA pesticide registration. The compounder was quite fortunate in that the US EPA OPP did not press criminal charges and the fine was a fraction of what it might have been, had the US EPA’s officials applied the standard $5,000 per incident (i.e., each customer site at which product was used) per day. It has been argued that if a compounder does not claim microbial contamination resistance or other antimicrobial performance properties in their written literature, they will not come under the US EPA’s OPP scrutiny. I wonder if the risk is worth the benefit.

In terms of antimicrobial pesticides, the MWF sector is an orphan the total MWF microbicide market is estimated to be <$200 million U.S.). With the continued consolidation of biocide manufactures, and increased cost of providing all of the toxicological test data needed to support new microbicide registrations, the only new microbicides likely to be made available for use in MWF are active ingredients that have been approved in non-MWF, large volume (i.e., >$50 million opportunity for a given product) markets.

Summary

What does the term “biocide-free” mean if MWF formulated with chemistries that are more toxic than the appropriately registered antimicrobial pesticides that they replace? I suggest that all stakeholders from compounders to end-users are safer if they use additives for which complete toxicological profiles are available rather than alternatives for which only limited data are available. The increased amount of information provided on microbicide labels doesn’t make them more hazardous than other industrial chemicals. Just as a rose by any other name is would smell as sweet, a microbicidal chemical – unregistered microbicide – by any other name is just as toxic – perhaps even more so.

As always, I look forward to receiving your questions and comments at fredp@biodeterioration-control.com.

¹ I originally created Figures 1, 2, and 3 for STLE’s MWF 240 Metalworking Fluid Formulation Concepts course, Module 3 Minimizing MWF Biodeterioration Risk.

DORMANT MICROBES IN METALWORKING AND OTHER INDUSTRIAL FLUIDS

John Cleese and Michael Palin of Monty Python’s Flying Circus in the “Dead Parrot Sketch”, first aired in December 1969.What is a dead microbe and why might we care?

I today’s post, I’m returning to a topic I first discussed in 2019 (https://biodeterioration-control.com/2019/07/). In the Monty Python’s Flying Circus “Dead Parrot Sketch”, John Cleese plays the role of an unhappy customer who believes that he has just purchased a dead parrot. Michael Palin – playing the shopkeeper – insists that the parrot is not dead. Rather, it is “simply napping.”

When we monitor microbial contamination in industrial systems, we are typically interested in both how much microbial contamination is present and what damage risk the population poses to the system and the fluids it contains.

Last week, I received an email from a metalworking fluid (MWF) manager who wrote: ““We have another situation with dormant bacteria. In this case we find we have to keep hitting it with biocide more and more often. When the bacteria do start to grow again as the biocide level drops, we see huge pH, alkalinity drops within a week and there is often a bad smell associated. I worry that this is partially due to a large population of dormant bacteria (10⁴ CFU mL^-1 to 10⁵ CFU mL^-1 on paddles) that is able to wake up and grow more quickly. Is there a way to get at these bacteria and kill them to reduce their population?”

With the MWF manager’s approval, today’s article draws heavily on my response to his email.

Dormant cells

Bacterial endospores

Endospores are special structures formed by a few types of bacteria. Endospores are metabolically inactive (i.e., dormant). There have been reports of microbiologists inducing endospores that have been dormant for more than a million years to germinate into vegetative (i.e., metabolically active) cells. Until recently (i.e., the past ~ 15 years), microbiologists believed that only endospore-forming microbes like Bacillus sp. (Gram +, spore-forming aerobic rods) and Clostridium sp. (Gram +, spore-forming anaerobic rods), could survive for long periods in a dormant – metabolically inactive state (Figure 1).

Fig 1. Fig 1. Bacterial endospores – a) Bacillus subtilis; b) Clostridium tetani. In these photomicrographs, the B. subtilis endospores appear as green spheroids and the C. tetani endospores appear as blue spheroids (sources: a) asmscience.org; b) https://www.researchgate.net).

Persister Cells

In the late 1980s, microbiologists started to report on the existence of persister cells – non-sporeformers that seemed to be able to withstand biocide treatment. In some respects, persister cells are like trees that are dormant during the winter but become active as spring arrives. When conditions are unfavorable, these cells become metabolically inactive and can remain in this state for thousands of years. Unlike endospore-forming bacteria, persister cells do not form any special structures.

Understanding of persister cells grew as biofilm research advanced. It turned out that persister cells were often resistant to biocide treatment because they were metabolically inactive – much like endospores but without the unique endospore cell wall chemistry. Thus, the study of persister cells evolved into the study of dormant cells. Thus, the terms persister and dormant are used to describe cells that can become metabolically during tough times and then become active after prolonged periods (1,000s of years) of inactivity. The biology of dormancy and reactivation is still a hot research topic.

Viable but not culturable (VBNC) cells

The rapid development of non-culture microbiological test methods, starting with protein concentration testing in the 1940s, ATP testing in the 1950s, and rudimentary genomic testing in the 1970s (my lab used to test seawater samples for total DNA concentration among other microbiological parameters), led to an awareness that not all microbes were readily detected by culture methods. In 1982, a ground-breaking study focused on a disconnect between the incidence of cholera disease among Chesapeake Bay area restaurant patrons and the inability of the local Department of Public Health to recover the bacterium Vibrio cholera form suspect oyster meat. A post-doctoral fellow at the University of Maryland decided to compare microscope direct counts with culture data. He came of with the idea of treating specimens with a reagent that prevented cell division but permitted cell growth. Metabolically active V. cholera cells would show up as >10x their normal size. Dormant and moribund cells would be visible as normal sized cells. Low and behold, shellfish samples that yielded no culturable V. cholera actually had 10⁶ to 10⁹ metabolically active – i.e., quite viable cells mL^-1! That work precipitated an avalanche of research on VBNC microbes.

The term VBNC includes two distinct categories of microbes.

Injured cells – The first category includes cells like the aforementioned V. cholerae that sometimes can be cultured but not reliably. These normally culturable cells are unable to reproduce on or in the growth medium that was designed to detect them if they are injured. Since the early 1980s, process steps have been added to culture test to help injured cells recover before they are cultured for enumeration.

Most types of bacteria – The second category includes microbe we do not yet know how to culture. They do not product colonies on any of the available growth media, under commonly used growth conditions (i.e., temperature, oxygen availability, etc.). Current estimates suggest that for every organism that has been successfully cultured, 1 million to 1 billion that exist in nature have not been cultured.

Metalworking Fluid Microbial Contamination Condition Monitoring

Choosing one or more test methods

If you test a population of people for height and weight you will find that – generally speaking – people’s weight increases with their height (Figure 2a). However, the relationship falls within a cloud around the trendline. Contrast this with the relationship between refractive index (°Brix) and metalworking fluid concentration ([MWF]) shown in Figure 2b. The trend lines in both graphs have the same slope, but the data point spread around the trend line is much greater for the height versus weight plot than it is for the °Brix versus [MWF] plot.

Fig 2. Correlations between pairs of parameters – a) human height versus weight (a significant, but weak correlation); b) refractive index (°Brix) versus [MWF] (significant and strong correlation).

I’ve discussed this concept in previous What’s New posts (see https://biodeterioration-control.com/microbial-damage-fuel-systems-hard-detect-part-3-testing/, https://biodeterioration-control.com/2019/07/, and https://biodeterioration-control.com/2020/03/)

The relationships among different microbiological test methods reflects the fact, that like Figure 2a, above, each method measures a different property (see https://biodeterioration-control.com/2017/07/).

Each test method tells a story

Between the dormant cell and VBNC cell factors, there are quite a few reasons that culture and non-culture testmethods can tell different stories. In some cases, culture data suggest a greater biodeterioration risk than actually exists (i.e., substantial bioburdens are not damaging the MWF). In others, culture data suggest that there is negligible biodeterioration risk but other data – such as ATP – indicate that the biodeterioration risk is great. This happens when a substantial portion of the metabolically active population is either non-culturable or clumped into masses (flocs) of cells and each such mass (100s to 1000s of cells) forms a single colony. So how do we interpret apparently conflicting data from two different methods. I’ll use culture (CFU mL^-1) and cellular ATP concentration ([cATP] in pg mL^-1) to illustrate the concepts.

When culture testing indicates high bioburden, but ATP data does not – if the population is dormant in the MWF but becomes metabolically active after being transferred to a growth medium, the population represents a potential risk. It is not causing damage at present, but could become metabolically active at some future point, as I will discuss below. As illustrated in Figure 3, the biodeterioration risk is moderate.

When culture testing indicates low bioburden, but ATP data indicates high bioburden – if a substantial percentage of the population is VNBC but metabolically active, it represents a current risk. Even though culture recoveries are minimal, the population is using MWF components as food and is producing acids and other metabolites that can degrade MWF performance. Per Figure 3, the biodeterioration risk is high.

It should be obvious that when both culture and ATP-bioburdens are low, the biodeterioration risk is low. Conversely, when both culture and ATP-bioburdens are high, the biodeterioration risk is high.

Fig 3. Biodeterioration risks based on culture and ATP-bioburden data.

Assessing microbicide performance in MWF systems

Based on the preceding background discussion, if microbicide treatments are not having the desired effect, it is important to assess whether the population in the treated MWF is dormant populations or not. because of the MWF dynamics, the available biocide concentration rapidly decreases to less than the critical (i.e., minimum effective) concentration with sufficient speed that bioburdens seem to yo-yo quickly (see the August 2018 What’s New article for an explanation of critical microbicide concentration).

For example, in a system with 10 % turnover per day, fluid loss through turnover rate will drop 2000 ppm biocide to 1,180 ppm in five-days. Add to that biological demand (microbicide consumption as it kills microbes) and chemical demand (microbicide reactions with other organic compounds in the MWF, dissolved metals, and salts, causing the microbicide molecule to either breakdown or become biologically unavailable) and it is easy to see how the concentration of biologically active microbicide can fall to below its critical concentration (1,000 ppm for triazine) within 4 to 5 days.

Dealing with rapidly restored bioburdens

Case 1 – Culturability is affected but [cATP] is not – If the population drops shortly after biocide addition, then the biocide is effective when it is present in the >critical concentration range. If you have a field test for microbicide concentration ([microbicide]), you can do a quick trial to track [cATP], CFU mL^-1, and [microbicide] before treatment and at 8h to 12h intervals post-treatment. If the treatment is effective, within 24h the [cATP] should drop by ³2 orders of magnitude. Determine the [microbicide] at which [cATP] begins to climb and the number of days post-treatment it takes for that to happen.

Figure 4 illustrates Case 1. Initial treatment causes both CFU mL^-1 and [cATP] to drop as expected. This indicates that the microbicide is effective at recommended end-use concentration. However, over time, both [microbicide] and CFU mL^-1 show a seesaw pattern. As the [microbicide] decreases, CFU mL^-1 increases. The [cATP] remains unaffected. This indicates that even at 750 mg L^-1 (ppm), the microbicide is working as a biostat – keeping most of the population dormant.

Fig 4. Microbicide effect on bioburden – Case 1.

Case 2 – [cATP] is affected but culturability is not – In this case, the CFU mL^-1 is not affected by microbicide dosing. However, there is an inverse relationship between [cATP] and [microbicide]. The [cATP] initially drops in response to 2,000 mg L^-1 microbicide dosing but recovers as the [microbicide] falls. Regardless of the [microbicide] the CFU mL^-1 remain within the test method’s (paddles) normal variability range (±1 order of magnitude). Figure 5 illustrates Case 2.

Fig 5. Microbicide effect on bioburden – Case 2.

Case 3 – [cATP] and culturability are affected – In this scenario, illustrated in Figure 6, microbicide treatment causes both parameters to fall. As the [microbicide] decreases, both culturable and ATP-bioburdens recover. Note that after a microbicide addition, the impact on CFU mL^-1 is faster than the effect on [cATP]. This is because cell injuries are likely to inhibit culturability almost immediately after treatment. However, it takes longer for cells to actually die. A full effective microbicide treatment will produce data similar to that shown inf figure 6. Keep in mind that Figures 4, 5 and 6 all pertain to a high-turnover system in which dilution is the primary factor affecting the microbicide’s half-life. That said, in systems with low turnover rates (< 5 % per day), the patterns will be similar but the x-axis will stretch out.

Fig 5. Microbicide effect on bioburden – Case 3.

Sorting out the three cases

AxP testing – AxP testing uses ASTM Test Method E2694 for Measurement of Adenosine Triphosphate in Water-Miscible Metalworking Fluids to obtain extracts that include ATP, adenosine diphosphate (ADP), and adenosine monophosphate (AMP). The “x” in AxP is used to indicate that the method tests for all three molecules. Recently, Drs. Peter Küenzi, Jordan Schmidt, and I collaborated to asses the relationship between MWF additives and Adenylate Energy Charge – AEC (see https://biomedgrid.com/fulltext/volume7/adenylate-energy-charge-new-tool-for-determining.001178.php). The AxP data are used to compute AEC. Dormant or moribund populations have AEC <0.5. Healthy populations have AEC ³0.7.

Per the preceding discussion of VBNC and dormant cells, high AEC with low CFU mL^-1signals the presence of an active but non-culturable population. Conversely, high CFU mL^-1 and low AEC signals that the microbes recovered by culture testing are not causing damage in the MWF. They are either dormant or dying off, but able to recover in the growth medium. I do not recommend AxP for routine testing. It is useful to make seemingly confusing or questionable data make sense.

Test for biofilm growth and biocide effect against biofilms

Commonly, we ignore biofilms (the November 2017 What’s New article discusses biofilms in fuel systems) growing on MWF system surfaces. Research has shown that both the dose needed to disinfect biofilms is typically 10x that used to kill planktonic – free-floating -cells (See December 2019’s What’s New). Additionally, the soak interval – period of contact – must be at least 24h. Biofilms periodically launch cells into the overlying fluid so that they can be transported to new surface colonization sites.

If you do not periodically eliminate biofilm populations, cells from MWF system biofilms readily reinfect the recirculating fluid as soon as the biocide concentration approaches the critical concentration. This is not an issue of dormant cells or VBNC cells. It is simply a reinfection process.

Use the DSA test method to evaluate biofilm accumulation in the system. If your DSA results are ³10³ pg cm^-2, you will need to do a full system clean out and recharge before you’ll be able to restore reliable bioburden control.

Summary

Although culture and ATP data generally tell the story, sometimes they do not.

If the population initially responds to microbicide treatment but recovers quickly, the two most likely causes are:

1. Reinoculation from biofilm communities, and
2. Recovery of the planktonic population when the microbicide’s half-life is shorted faster than assumed.

ATP by both ASTM Test Method E2694 & DSA testing can tell you if Cause 1 is at play. If biofilm growth is causing the data pattern you have reported, you will need to do a drain, clean, and recharge to break the cycle.

ATP, culture, & [microbicide] can tell you if cause 2 is at play. If short half-life is the issue, you’ll have to rethink your dosing plan.

AxP can tell you if there is a dormant population affecting your test results.

For more information, contact me at fredp@biodeterioration-control.com

Minimizing Covid-19 Infection Risk In The Industrial Workplace

Electron microscopy image of the SARS-CoV-2 virus.

COVID-19 Infection Statistics

Although anti-COVD vaccines are rolling out and people are being immunized, as of early late December 2020, the rate at which daily, newly reported COVID-19 cases has continued to rise (Figure 1). In my 29 June 2020 What’s New article I discuss some of the limitations of such global statistics. In that post, I argued that the statistics would be more meaningful if the U.S. Centers for Disease Control’s (CDC’s) morbidity and mortality reporting standards were used. Apropos of COVID-19, morbidity refers to patients’ cases reported and having the disease and mortality refers to COVID-19 patients who die from their COVID-19 infection. Both morbidity and mortality are reported as ratios of incidence per 100,000 potentially exposed individuals. I illustrated this in my portion of an STLE webinar presented in July 2020.

Fig 1. Global incidence of new COVID-19 cases – daily statistics as of 23 December 2020 (source: coronavirusstatistics.org).

What Do the Infection Statistics Mean?

Social scientists, epidemiologists, and public health specialists continue to debate the details, but the general consensus is that the disease spreads most widely and rapidly when individuals ignore the fundamental risk-reduction guidelines. It appears that COVID 19 communicability is proportional to the number of SARS-CoV-2 virus particles to with individuals are exposed. Figure 2 illustrates the relative number of virus particles shed during the course of the disease.

Fig 2. Relationship between number of SARS-2CoV viruses shed and COVID-19 disease progression.

Notice that the number of viruses shed (or dispersed by sneezing, coughing, talking, and breathing) is quite large early on – before symptoms develop fully. It’s a bit more complicated than that, however. Not all infected individuals are equally likely to shed and spread the virus. All things being apparently equal, some – referred to as super-spreaders – are substantially more likely than others to infect others. Although people with or without symptoms can be super-spreaders, those who are infected but asymptomatic are particularly dangerous. These folks do not realize that they should be self-quarantining. A study published in the 06 November 2020 issue of Science (https://science.sciencemag.org/content/370/6517/691) reported that epidemiological examination of millions of COVID-19 cases in India revealed that 5 % of infected people were responsible for 80 % of the reported cases.

What Shall We Do While Waiting for Herd Immunity to Kick-In?

The best strategy for avoiding the disease is to keep yourself physically distanced form others. Unfortunately, this advise is all but worthless for most people. We use public transportation to commute to work. We teach in classrooms, work in offices, restaurants, medical facilities, and industrial facilities in which ventilation systems are unable to exchange air frequently enough to minimize virus exposure risk. The April 2020 ASHRE Position Document on Infectious Aerosols recommends the use of 100 % outdoor air instead of indoor air recirculation. The same document recommends the used of high-MERV (MERV – minimum efficiency removal value – 10-point scale indicating the percentage of 0.3 µm to 10 µm particles removed) or HEPA (HEPA – high efficiency particulate absorbing – able to remove >99.9% of 0.3µm particles from the air) filters on building HVAC systems. Again, as individuals who must go to work, shop for groceries, etc., outside our own homes, we have little control over building ventilation systems.

Repeatedly, CDC (Centers for Disease Control), HSE (UK’s Health and Safety Executive), and other similar agencies have offered basic guidance:

1. Wear face masks – the primary reasons for doing this is to keep you from transmitting aerosols and to remind you to keep your hands away from your face. Recent evidence suggests that that although masks (except for ones that meet N-95 criteria) are not very efficient at filtering viruses out of the air inhaled through them, they do provide some protection.

2. Practice social distancing to the extent possible. The generally accepted rule of thumb is maintaining at least 6 ft (1.8 m) distance between people. This is useful if you are in a well-ventilated space for relatively short periods of time but might be insufficient if you are spending hours in inadequately ventilated public, industrial, or institutional spaces.

3. Wash hands thoroughly (at least 30 sec in warm, soapy water) and frequently. The objective here is to reduce the chances of first touching a virus laden surface and then transferring viruses into your eyes, nose, or mouth.

Here are links to the most current guidance documents:

CDC – How to Protect Yourself and Others – https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html

CDC – Interim Guidance for Businesses and Employers Responding to Coronavirus Disease 2019 (COVID-19), May 2020 – https://www.cdc.gov/coronavirus/2019-ncov/community/guidance-business-response.html

HSE – Making your workplace COVID-secure during the coronavirus pandemic – https://www.hse.gov.uk/coronavirus/working-safely/index.htm

UKLA- HSE Good Practice Guide – http://www.ukla.org.uk/wp-content/uploads/HSE-Good-Practice-Guide-Sept20-Web-LowresC.pdf – discusses health & safety in the metalworking environment.

WHO – Coronavirus disease (COVID-19) advice for the public – https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public

Remember: Prevention really Means Risk Reduction

It is impossible to reduce the risk of contracting COVD-19 to zero. However, timely and prudent preventative measures can reduce the risk substantially so that people can work, shop, and interact with one another safely. Guidance details continue to evolve as researchers learn more about SAR-CoV-2 and its spread. However, the personal hygiene basics have not changed since the pandemic started a year ago. If each of us does our part, we will be able to reduce the daily rate of new cases dramatically, long before the majority of folks have been immunized.

For more information, contact me at fredp@biodeterioration-control.com

METAWORKING FLUIDS, 3RD EDITION NOW AVIALABLE!

Thirteen years after Metalworking Fluids, 2nd Ed. was published, the third edition is now available. Metalworking Fluids, 3rd Ed. Jerry Byers, Ed. has just been published (ISBN, Hardbound: 978-1-4987-2222-3; E-book: 978-1-14987-2223-0) and is available from STLE, CRC Press, or Taylor & Francis.

MWF 3rd. Ed. promises to become the new MWF bible. All of its chapters reflect either substantial updates or all new material. I recommend this new volume most strongly to all metalworking industry stakeholders.

Full disclosure, I wrote Chapter 11 – Microbiology of Metalworking Fluids. Many of the other chapters were written by colleagues on STLE’s Metalworking Fluid Education and Training Subcommittee.

PROTOCOL FOR DIFFERENTIATING BETWEEN BACTERIAL AND FUNGAL ATP NOW PART OF ASTM E2694

ASTM E2694, Method for Measurement of Adenosine Triphosphate in Water-Miscible Metalworking Fluids, was first approved in 2009. The 2016 revision of the method has just been published by ASTM (www.astm.org). This version includes a new Appendix X4 that provides a protocol for differentiating between bacterial and fungal contamination in metalworking fluids. I had first written about this protocol here in my 04 May 2015 blog. The original research on which the ASTM E2694 revision was based was published in 2014: Passman, F.J. and Küenzi, P., “A Differential Adenosine Triphosphate Test Method for Differentiating between Bacterial and Fungal Contamination in Water-Miscible Metalworking Fluids” International Biodeterioration & Biodegradation (2014), http://dx.doi.org/10.1016/j.ibiod.2015.01.006 0964-8305.
Appendix X4 is meant to be used only on samples that have high cATP concentrations as determined by the basic E2694 test. I generally consider ≥1,000 pg/mL to be high cATP, but others might choose to be more conservative. The differential method guides microbicide selection. If the ATP-biomass is all from bacteria, then a tankside addition of bactericide is generally the appropriate treatment. If it is from fungi, then a fungicide will be needed. A broad-spectrum microbicide or compatible bactericide and fungicide are needed to control an infection that is due to a combination of bacteria and fungi. For more information, contact me at 609.716.0200 or fredp@biodeterioration-control.com.

WHERE HAVE ALL THE MICROBICIDES GONE? LONG TIME PASSING…

How many of you recall the Bob Seeger song: Where have all the flowers gone? It seems that it might be time to modify the lyrics by replacing the word flowers with biocides approved for use in metalworking fluids (MWF). I admit, that’s a mouthful, but the reality is comparable to that behind the original song. The list of active substances for which Biocidal Products Regulation (BPR) dossiers have been submitted includes a mere 27 actives intended for use in MWF. Less than 10 years ago, there were more than 100 options. The dust hasn’t yet settled in the USA, but once the US EPA’s Office of Pesticides Programs rules on the maximum permissible dosage of triazine in MWF later this year, it’s likely that the ASTM E2169, Table 2 list of active ingredients approved for use in MWF will be a fraction of its original length. Perhaps, when compared with our European friends, we are still lucky in the USA. A literal reading of the BPR’s definition of a Biocidal Product suggests that all MWF are Biocidal Products. The UEIL is advocating that MWF be formally recognized as Treated Products (the cost impact is an estimated $250,000 U.S. per MWF formulation – not trivial). Regulators have promised to give UEIL’s arguments full consideration, but nothing has yet been put in writing. I reviewed the latest state of affairs in my January 2016 TAE presentation. Please contact me if you are interested in receiving a copy of the manuscript: Impact of Biocidal Product Regulation on Microbial Contamination Control in Metalworking Fluids.

Using ATP to evaluate biofilm dispersants.

If you will be attending the STLE Annual Meeting on 15 through 19 May 2016, be sure to join me at the Metalworking Fluids Technical Session III, in the Silver Room, Bally’s Las Vegas, NV. At 0830h, on Tuesday 17 May, I’ll be presenting my paper: “Adenosine Triphosphate Testing to Evaluate Biofilm Dispersants.” The paper discusses the use of LuminUltra Technologies Limited’s QGO-M and DSA test methods to compare the efficacy of a number of different formulations for removing biofilm from pipe surfaces without being biocidal. As regulators increasingly restrict the use of MWF microbicides, it is becoming increasingly important to develop non-biocidal biodeterioration prevention strategies. My STLE presentation will speak directly to this issue. I’m looking forward to seeing you in Las Vegas. Please contact me directly (see “REQUEST INFORMATION” on BCA’s home page) if you would like to schedule a conversation during the STLE Annual Meeting.

The Truth is Out There…

For those of you who are interested in metalworking fluid microbiology and microbial contamination control, I invite you to read my March 2016 Tribology and Lubrication Transactions TLT) article: MWF Biocides Part II – Science vs. Fiction.
This was an accidental article that I was asked to write in response to an error-laden article that had appeared in TLT’s November issue. The earlier piece had been written by an individual whose familiarity with the topic was limited to the research performed in the process of drafting the TLT submission. I had not yet read the article when I started receiving flaming emails from industry colleagues who mistakenly believed that I had an editorial role and had somehow approved the article for publication. Initially, my plan was to write a letter to the editor. Indeed, I wrote a draft letter listing each error and the correct information (with relevant references cited as appropriate). The letter morphed into the March article. To be sure that I wasn’t just offering my personal opinions, I recruited log time colleagues Drs. Neil Canter and Alan Eachus and Mssrs. Jerry Byers and Richard Rotherham to co-author the article. I am much indebted to each of them for their contributions to the effort.
MWF Biocides Part II focuses primarily on the scientifically unsupportable conflation of formaldehyde (HCHO) and formaldehyde-condensate microbicides (FCM). The toxicological profiles of FCM differ among specific chemistries, but as a group are substantially different from HCHO. Moreover, although regulators assume that 100% of the HCHO in FCM will end up in the air above metalworking fluids (MWF) threated with FCM, data prove otherwise. Over the past couple of years, the number of microbicides approved for use in MWF has plummeted. In Europe there are only 27 listed biocidal substances (most are still going through regulatory review) that can be used in MWF. In the U.S., by last summer, the US EPA’s Office of Pesticides Programs will most likely issue guidance that will determine the future availability of FCM. In addition to clarifying the FCM issues that had been misreported in the November article, the March article sets the record straight on nearly 30 other misstatements made in the earlier publication.
Please contact me at fredp@biodeterioraiton-control.com for a copy of the MWF Biocides Part II.

Legionella pneumophila in Metalworking Fluids

I’m sharing an email exchange that I had with a colleague who had asked about the risk of L. pneumophila (the microbe that causes Legionnaire’s disease) in MWF.
Thank you for posting your query to BCA’s website.

You wrote:
“I wondered if you could help me answer a customer’s question. One of my customer’s machine tool operators is in the hospital being treated for Legionnaires’ disease. My customer asked me if the Kathon 886 MW or Kathon CC kills this strain of bacteria. I really appreciate your help and advice. I attend the annual STLE meeting every year and hear you speak on maintaining and monitoring metal working fluids, so I thought you would be the best source to ask. The Legionnaires’ disease was most likely contracted in Tennessee while this gentleman was on vacation. Other machine operators are now afraid they might contract the disease through the metal working fluids in the plant.
Thank you for your time and thoughts.”

The short answer is yes.

Not long after Legionella pneumophila was identified as the disease agent that caused Legionnaire’s disease, Rohm & Haas tested Kathon WT1.5 efficacy against the bacterium. WT1.5 is just Dow’s (formerly R & H) water treatment market label for the 1.5% active product we use as Kathon 886MW and 886MW 1.5 in the MW industry.

Keep in mind that L. pneumophila is ubiquitous. If you recall the incident at Ford’s Le Brea, OH plant some years ago, four machinists came down with Legionnaire’s disease. Attempts to detect L. pneumophila from MWF systems all failed. An immunological survey of all of the plant’s employees revealed that the majority has antibodies to L. pneumophila. Other immunological surveys (populations outside our industry) have demonstrated that the majority of the population has been exposed to the microbe (i.e.: has the antibodies). Most of the time, folks who contract the disease have other health problems that render them more susceptible than the general population. Back to Le Brea. That incident and a cluster of Pontiac Fever cases at a Pontiac Plant in Windsor Ontario in 1981 are the only two clusters of Legionnaire’s disease that have been reported in the MW industry. The 1981 outbreak was caused by L. feeleii growing in the facility’s cooling towers. The source of L. pneumophila at Le Brea was never confirmed.

From what we know, workers are much more likely to be at risk from improperly controlled heat exchange systems/cooling towers than from MWF.

Archive for the ‘MWF Microbiology’ Category

MICROBIOLOGY FOR THE UNINITIATED – PART 1: WHAT ARE MICROORGANISMS AND WHY SHOULD WE CARE?

WHAT’S IN A NAME – ARE BIOCIDE-FREE METALWORKING FLUIDS LESS TOXIC THAN THOSE FORMULATED WITH BIOCIDES?

DORMANT MICROBES IN METALWORKING AND OTHER INDUSTRIAL FLUIDS

Minimizing Covid-19 Infection Risk In The Industrial Workplace

METAWORKING FLUIDS, 3RD EDITION NOW AVIALABLE!

PROTOCOL FOR DIFFERENTIATING BETWEEN BACTERIAL AND FUNGAL ATP NOW PART OF ASTM E2694

WHERE HAVE ALL THE MICROBICIDES GONE? LONG TIME PASSING…

Using ATP to evaluate biofilm dispersants.

The Truth is Out There…

Legionella pneumophila in Metalworking Fluids

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