If someone asked you what substance on Earth was the most toxic on a per gram basis, what would you say? Mercury? Lead? Dioxin? PCBs? It turns out it's a toxin produced by the bacterium clostridium botulinum. The botulinum toxin that the bacteria produces has a LD50 of approximately 10 ng/kg, which will kill 50% of those exposed by inhalation. To put that in perspective, that’s a dose the size of one pollen grain that can kill an average-sized adult. Botulinum toxin is a neurotoxin, paralyzing muscles and typically causing death by preventing contraction of the muscle responsible for breathing. Ingestion of the toxin or infection with the bacteria causes a rare but serious illness called botulism, historically associated with eating improperly canned foods.
Alternatively, when the toxin is diluted many, many fold, as in formulations of Botox, it can be injected into targeted areas to prevent muscle contractions that result in wrinkles. Use of Botox for cosmetics is a relatively recent development. Originally, injections were used to alleviate disorders that cause uncontrolled muscle twitching and crossed eyes. A relatively new use of Botox is treatment of chronic migraines. Botulinum toxin is just one example in the world of microbiology where humans have identified a way to use a naturally harmful product for human benefit.
Welcome to the world of microbiology.
A thorough course in microbiology will involve five main areas:
In each main area there is an enormous amount of material to be covered and knowledge to be gained. It's not uncommon for textbooks in microbiology to have 100 chapters, spread throughout the broad topics given above.
Excellent books in microbiology can be found on Google and Amazon.com. In addition, there is a terrific collection of microbiology web links offered by McGraw Hill. Finally, students can take advantage of several good online microbiology tutorials.
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