Science WebQuests
Beneficial Bacteria
Harmless and beneficial bacteria far outnumber harmful varieties. Thousands of bacterial species live in humans, and many provide health benefits to humans. Bacteria aide in digestion, and grow on your skin and help to prevent the growth and establishment of colonies of pathogenic bacteria.
Because they are capable of producing so many enzymes necessary for the building up and breaking down of organic compounds, bacteria are employed extensively by humans for—
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soil enrichment with leguminous crops (nitrogen cycle)
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preservation by pickling food (pickles, pickled okra, sauerkraut)
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fermentation (manufacturing of alcohol, vinegar, and certain cheeses)
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decomposition of organic wastes (septic tanks and sewage disposal)
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decomposition of toxic wastes
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curing tobacco
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retting flax (using the bacteria to break down cellular tissues)
Bacteria frequently make good objects for genetic study: large populations grown in a short period of time facilitate detection of mutations, or rare variations
Pathogenic Bacteria
Bacterial parasites that cause disease in humans, animals, and/or plants are called pathogens. Among bacterial plant diseases are leaf spot, fire blight, wilts, bacterial streaming, and watersoaking. Animal diseases caused by bacteria include tuberculosis, cholera, syphilis, typhoid fever, and tetanus. Some bacteria attack the tissues directly; others produce poisonous substances called toxins. Natural defense against harmful bacteria is provided by antibodies.
Certain bacterial diseases, such as tetanus, can be prevented through vaccinations., which is the injection of antitoxins or of a serum containing antibodies against specific bacterial antigens. Certain other bacterial parasites are treated or killed by using antibiotics.
New strains of more virulent bacterial pathogens, many of them resistant to antibiotics, have emerged in recent years. Many believe this to be due to the overuse of antibiotics such as prescription medicines as well as the overuse of antibiotic soaps and hand sanitizers. Such overuse increases the likelihood of bacterial mutations. For example, a variant of the normally harmless Escherichia coli has caused serious illness and death in victims of food poisoning.