I have come across some information concerning botulism in soil and it bugs me even though I’m probably not in danger of it judging by the information I’ve found on it. I get a lot of produce really fresh but I wash it thoroghly. It made me curious though. How likely is it for any given soil sample to have botulism in it?
I can’t give you a number, but it’s not at all unlikely. It’s a fairly common bacteria. Of course, the odds that it will be in high enough concentration to hurt you aren’t good.
I think that the poison itself is produced when the botulin bacteria grows in a vacuum, such as created in pressure canning.
The toxin isn’t only produced when the bacteria is growing in a vacuum. It’s promoted by “under nutrient-rich anaerobic conditions” - that is to say, an environment with no oxygen but plenty of sugars and proteins (or free amino acids) etc.
In conditions that are unfavorable for growth of Clostridium botulinus, such as high oxygen, low concentrations of water, etc., it will produce extremely hardy spores which are remarkably resistant to the extreme temperatures and pressures used in canning or even medical autoclaves. A contaminated batch of say beef barley soup that isn’t quite fully sterilized can allow spores to survive, germinate, and slowly grow (anaerobic growth tends to be slow, compared to oxygen-using aewrobic growth) and release toxin which accumulate. These toxins can persist in harmful or even lethal concentrations even if the soup is thoroughly cooked before serving
This is ordinary botulism - a food poisoning from a pre-formed toxin, rather than an infection. Other serious clostridium diseases are often infections, however
Among the foods that often contain spores of various clostridium species is honey. For this reason, it is not recommended that honey (especially raw or farm-processed honey) be given to babies. The spores can germinate in the child’s gut, and colonize it, resulting in a chronic or acute endogenous poisoning often called 'infantile botulism". The gut of an older children or adult will already be colonized with plenty of bacteria, which are better adapted to those conditions. They will outcompete and outgrow the Clostridia, so it never gets a foothold, so honey is safe for them.
Another serious Clostridium disease is a diarrheal disease now common in hospitals and nursing facilities, due to Clostridium difficile. When I was doing my medical training, we had entire wings and wards that were contaminated with this bacteria (spread by the free-flowing diarrhea contaminating staff, mobile equipment, walls, carts, etc. Since even a trace contamination could re-ignite much later, decontamination was almost impossible- some wards suffered new outbreaks after being shut down and scrubbed floor to ceilling with antiseptics.
Diarrhea isn’t just embarrassing. It can cause enough fluid, electrolyte and nutient loss to be quickly life-threatening, and C. diff generally produces a fairly serious diarrhea, especially in the infirm - who are likely to be exposed in hospitals.
Still, aside from the handful of dangerous Clostridium disease, most species of Clostridium aren’t particularly harmful. In fact, something like 15-30% of all healthy individuals (IIRC, last I checked) have some fairly harmless species of Clostridium growing in their gut. They may even help by outcompeting dangerous Clostridia.
All this information is off the top of my head, so I have misspoken on minor technicalities, but I have degrees in medicine and molecular biology, and would stand by the statement as a whole.
The local PBS station ran a documentary this evening, *The Sacred Balance - The Fire of Creation, * in which a scientist claimed that a teaspoon of soil from an old-growth forest contains more than 20,000 species of bacteria and 10,000 species of fungus.