Gerry Skews. Jan 2023.
How wonderful it is to write a few notes about the ugly bugs that impact on food health. I always enjoyed working on micro-organisms in earlier years, for the most part they were things you could actually see without the aid of an Electron Microscope or a big assed dollop of imagination.
“Micro organisms are all pervasive, you can hardly sneeze without finding millions of the pesky little things.”
I like the idea that there are likely to be over 1million SPECIES of bacteria in 30 grams of forest topsoil... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3160642/ but alas only about a billion overall, Do not despair; it's not just bacteria thats out there, there are millions of viruses, and fungi that can absolutely ruin your day. (or ferment your beer depending on your perspective)
Characterisation & Classification
The ability to characterise organisms using a definitive technique has been something of a holy grail for thousands of years. Physical effects of dosage gave way to physical measurements, gave way to differrential comparisons, gave way to functional biology gave way to phenotyping (Cellular classification) and genotyping (Genetic classification), basically improving resolution and differentiation along the way.
So whilst we still use selective media and staining and fluorescence, and characteristic behaviour (can it live in Oxygen or not) the advancement of molecular characterisation holds out hope of extending our understanding, detection and measurement of these pesky little things.
We have seen that there are thousands of different strains of bacteria, some cause injury and death (e.g. Clostridium Botulinum) some act as simple nerve blocking agents (e.g. Clostridium Botulinum) yes this is the same organism producing one and the same neurotoxin just diluted differently.
Equally, bacteria that has the same name can be completely different. The toxin produced by Listeria monocytogenes can cause serious illness and death in the immunocompromised whereas the toxin produced by Listeria Welshimeri is harmless (possibly even beneficial as a xenobiotic). Saccharomyces cerevisiae is the yeast that is used in Baking & Brewing, once activated it farts carbon dioxide and makes alcohol, pretty much like us humans.
In point of fact, the important thing is to know what you are dealing with, and to do everything possible to control the food production environment to prevent the bad bugs from getting through the system or spoiling the product.
Speciation & Genetics
Few secrets will remain in the world of speciation thanks to the advancement of genomics (DNA & RNA Sequencing). I remember the news in 1984 that the Barr Epstien Virus had been successfully sequenced, thinking to myself that's great news, wait, what does the Barr Epstein Virus do?, then I remembered, it's the virus that causes Herpes, Wow I thought, some poor Cambridge University nerd asked his PhD supervisor, "what shall I sequence sir? " "Go sequence a Zit young man". 172,282 base pairs later, he gets his paper published in Nature... Just proves that good science is always worth that extra squeeze.
Micro-organisms have feelings too..
There are however billions of organisms that do us a lot of good. Indeed we could not really survive
on the planet without bacteria, viruses and fungi breaking down most of the organic waste and converting it into media that can be used for fertiliser and other useful by-products.
The essence of life on the planet depends entirely on the environment in which it lives.
MRS. GREN has the characteristics of all living organisms
Movement, Reproduction, Sensitivity, Growth, Respiration, Excretion, Nutrition
In other words mess with the environment and you mess with the viability of life.
Visitors to the ugly bug ball
This is not a definitive list of all of the bacteria, viruses and fungi that are harmful but outlines some of the key ones identified in HACCP plans typically associated with food production.
Key information is drawn from several sources including https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7150063/
The bouncers at the ball
Dealing with bacteria, fungi and viruses requires both prevention and intervention. By preventing bacteria from getting on the food or by "processing" it to remove it we are reducing risk. However it's unbelievably difficult to deal with an invisible miscreant, we turn to history, the bible, and science to develop working strategies.
Key things that impact on microbial viability.
Temperature
Oxygen
Energy Synthesis
Reproductive efficacy
It's slightly more convoluted than that because there are different ways to impact the cells. For example we all know that cooking kills bacteria but chilling or freezing does not.. Equally blasting an organism with short wavelength UV disrupts molecular components but then we risk ingesting mutated DNA. So we use what works pending a revolutionary discovery.
As an example we have identified Clostridium botulinum as a potential contaminant in a new fish product.
Clostridium botulinum are rod-shaped bacteria (also called C. botulinum). They are anaerobic, meaning they live and grow in low oxygen conditions. The bacteria form protective spores when conditions for survival are poor. The spore has a hard protective coating that encases the key parts of the bacterium and has layers of protective membranes. Within these membranes and the hard coating, the dormant bacterium is able to survive for years.
From published data we know that most variants of C.bot can only survive at temperatures between 3 and 45 degrees C. So cooking the products will destroy the bacteria, as long as the temperature is greater than 50 degrees (variant A and B). We also know that the organism cannot do well without "water" so we can de-hydrate the product, (Aw below 0.97) and we also know that high acidity (below 4.5 pH) or very high alkalinity (above 9 pH) will screw it up. All this is useful information but needs to be translated into a risk profile. There is absolutely no point in relying on a vacuum pack to protect smoked Salmon against C.bot it simply won't work. The process must change the pH, or raise the temperature or prevent the organism from coming close to the product.
Summary
Knowledge is power when it comes to microbial risk in food safety. There are dozens of organisms that bring risk and while normal human gut flora is pretty good at dealing with a lot of bacteria it cant deal well with some of the real nasty ones. So when developing food safety and risk plans its not only important to understand the risks its a legal obligation to do all you can to mitigate risk. This article has taken a light hearted angle to raise awareness of microbiology but the impact must be taken seriously, every week there are many incidents of food bourn illness, most are inconvenient, some kill people, while prison might be an inconvenience to you, death is more than an inconvenience to others.