Wonders in Miniature - The Types of Bacteria that Impact Mankind

There are thousands of types of bacteria representing the simplest and oldest form of life on earth. These ubiquitous creatures dwell within us and around us in astronomical numbers and include both dangerous and helpful bacteria. The average person carries around a quarter pound (100 grams) of various types of bacteria in their gut, skin and mouth. They settle into the moist, nutrient-rich, protected folds of our skin and multiply by dividing, leading us to the old joke, "Why do bacteria fail at math tests? Answer - Because they think multiplication is the same as division."

There are types of bacteria that can survive the most hostile environments from Antarctic ice sheets and other types that are fine in the boiling geyser pools of Yellowstone. Recently, scientists discovered bacteria thriving two miles deep in a South African gold mine, living on nothing more than sulfate minerals and hydrogen split from water by uranium radioactivity. The many types of bacteria in existence prove that life is far more adaptable than most believe, giving hope in finding extraterrestrial life on distant, inhospitable planets.

The first person to taste spoiled milk certainly was a brave soul, but from it came cheese and yogurt. Through centuries of experimentation, specialty cheeses such as Swiss with its famous holes came about because of the helpful bacteria that give off carbon dioxide during fermentation. Brevibacterium give limburger its strong odor and also cause foot odor by the break down of proteins in flaking skin between the toes.

Beer is brewed by fermenting yeasts, producing alcohol from sugar. However it is helpful bacteria that give beer its complexity and acidity. Most brewers go to extremes to prevent bacterial contamination in ales and lagers; however, Belgian-style wheat beers need certain types of bacteria for their characteristic acidic taste. On the tail end of the brewing process, the University of Queensland in Australia is teaming up with a beer maker to generate electricity from brewery wastewater. A special fuel cell has been developed in which helpful bacteria convert waste sugars, starch and alcohol into electricity and clean water.

In 1975 Steven Lindow of the University of Wisconsin discovered that one of the common types of bacteria, Pseudomonas syringae, which is found on leaves and grass, produces a protein that enhances frost formation. The protein from this helpful bacteria, sold under the brand name Snomax(R), is now used worldwide at ski resorts to increase the efficiency of making snow.

On the flip side, P. syringae's gene that produces the frost-inducing protein was removed to create what was thought to be helpful bacteria that, when sprayed onto crops, could prevent frost damage. Even though its use could save millions in crop damage each year, the genetically altered bacteria, under the name Frostban, failed to gain wide-spread acceptance and was challenged by ecologists and activists who feared the organism would spread and mutate in unforeseeable ways.

In another clever use of helpful bacteria, the world's strongest glue to adhere to wet surfaces may soon be available. Caulobacter crescentus bacteria attach themselves to rocks in streams and lakes using long threads of sticky sugar molecules. The natural, nontoxic adhesive made from this helpful bacteria is two to three times stronger than super glues and scientists are hopeful that it can be mass produced in the near future.

We also benefit from the helpful bacteria that live inside of us. It is estimated that between 5,000 and 10,000 different types of bacteria inhabit the human body. In the large intestine a complex microflora community synthesizes vitamins such as vitamin K, folic acid and biotin. Within days after birth, newborns are colonized by Lactobacilli, a group of helpful bacteria that convert milk protein to lactic acid. The bacteria remain present throughout life. These microbes are widely used in the production of sour milks, yogurt and cheese.

There is increasing evidence of the benefits of supplementing the body's natural gut flora with probiotics, which are living types of bacteria considered beneficial to the human body. Probiotics improve the balance of the intestinal microflora, assist in digestion, and enhance immune function. These helpful bacteria are found naturally in fermented foods such as miso, tofu and yogurt. A person's bacterial balance can be thrown off by taking antibiotics or by unfriendly types of bacteria overpopulating due to stress or illness. When this happens, the body becomes susceptible to conditions like diarrhea, irritable bowel syndrome, and inflammation.

Our mouths are also a prime locale to host many types of bacteria. Because we eat many of the same foods that bacteria like, our teeth are vulnerable to the acidic byproducts of bacterial metabolism. Our teeth are 97% calcium and when enough of the calcium is dissolved by the acid, the tooth surface (enamel) breaks and forms a hole. The types of bacteria that cause decay are four species of Streptococcus. An interesting sidebar is a biotech company, Oragenics, has approval from the FDA to perform studies on a bacterial treatment to replace the bacteria that convert sugar to acid with genetically modified helpful bacteria that do not produce acid.

Food borne illness inflicts between 24 and 81 million of us each year in the United States. Food poisoning caused by bacteria is the most common form of the illness and 90% of the cases are caused by only eight types of bacteria. Consuming as few as 15-20 cells will cause the onset of symptoms within 6 to 48 hours. It is estimated that from 2 to 4 million cases of salmonellosis occur in the U.S. annually.

Another culprit in food poisoning is Escherichia coli, more commonly referred to as E. coli. Most E. coli serve as helpful bacteria that reside without effect in our intestinal tract where they synthesize vitamin A. However there are rare classes of E. coli that are enterovirulent (entero = gut ; virulent = poison). These particular types of bacteria produce potent toxins that damage the lining of the intestine, leading to intense abdominal cramps and bloody diarrhea. Ten or more bowel movements in a single day are common. The resultant dehydration and loss of electrolytes can be deadly if left untreated. The ingestion of as few as 10 organisms is considered the infective dose.

Humans are exposed to billions of types of bacteria daily. Most of them are helpful bacteria that are vital to our survival and well-being. A very few types of bacteria are deadly if ingested and our body's natural defenses are unable to eradicate them. Nonetheless the benefits these tiniest of creatures bring to our world are countless and our improving understanding of helpful bacteria is spurring product innovation in the fields of medicine, healthcare, food technology and leisure activities.