Lactobacillus acidophilus is the bacteria in "acidophilus" milk that many people drink to help relieve intestinal distress, like diarrhea and constipation. Some evidence suggests that this bacterium is beneficial in warding off colon cancer.
Yogurt is made using two kinds of bacteria, one species of Lactobacillus and one of Streptococcus. One is responsible for the production of acid to curdle the milk and turn it into yogurt; the other imparts the pleasant aroma one associates with yogurt.
The cyanobacterium Spirulina is used directly as a food source in areas of Africa and can also be found in health food stores in the United States.
All of us have, at one point or another, been somewhat frustrated at waiting for long periods in a doctor's office, only to be informed that our illness is due to a viral infection and antibiotics will not help.
Antibiotics fall under the realm of antimicrobial chemotherapy. Bacteria are killed or damaged in a number of fairly specific ways by antibacterial medications. Some antibiotics prevent cell wall synthesis,while others inhibit the synthesis of nucleic acids in bacterial cells. Still others block important metabolic pathways by knocking out key enzymes.
Since viruses must make use of your cells' machinery for replication, it has been thought that antiviral medications would just as likely harm your body cells.
A number of antiviral medications are being developed that block the penetration of viral particles into cells. Interferons, which are antiviral agents produced by your body, are also under investigation as preventative measures to protect against viral invasion.
Because so many antimicrobial agents are in use continuously, many resistant strains of bacteria and viruses are surfacing. There are a couple of important points to remember to help prevent the development of antibiotic-resistant strains. If directed to do so, take the entire course of antibiotic you are given. This helps to prevent antibiotic-resistant strains from arising within you, which can then be passed along to others. Refrain from using antibiotics in animal feed. Many tons of antibiotics are consumed by cattle, pigs, and chickens, which only adds to the problem. Last, seek antibiotics only when really necessary. If you are in reasonably good health, your body should be able to ward off many infections on its own.
Many people are unaware of the commercial uses of algae. To enhance student recognition of this group, share the following information.
Four components of marine algae, like kelp, are useful commercial products. Agar, a product of red algae, is used as a microbiological medium for microbial growth. Carrageenan, also from red algae, is used as an emulsifier in ice cream, a binder in toothpaste, a thickener in shaving cream, and a thickener in soups and sauces. Alginates, from the cell walls of brown algae, help make ice cream and frostings smooth, thicken paints, and are used in making dental impressions. Diatom cells, which contain silicon dioxide within their walls, are used in polishes, paper products, insulation, and construction. Diatomaceous earth makes a good polisher for fine surfaces.
Mammals mate by sexual reproduction. Discuss with your students the advantages and disadvantages of different mating systems in mammals as well as in humans.
What are the advantages to the male if he is promiscuous rather than monogamous? Disadvantages? Ask the same question for females.
Be sure to include the areas of passing on one's genes to the next generation, caring for infants and rearing offspring, and providing food and shelter. Which system is most likely the one that evolved in humans, and why?
Many of us have experienced diseases caused by fungi, but may not be aware that a member of this diverse group was the culprit. Share with your students information, such as the following, about a number of diseases caused by fungi.
Since fungi are primarily terrestrial, many have become pathogenic and infect animals and plants. Many of the major plant diseases are caused by fungi. In humans, one of the most common diseases caused by fungi are the ringworms. A person can have ringworm of the beard (tinea barbae), ringworm of the body (tinea corporis), ringworm of the scalp (tinea capitis), ringworm of the feet (tinea pedis), ringworm of the groin (tinea cruris), ringworm of the hands (tinea manuum), or ringworm of the nails (tinea unguium).
Some fungal diseases are opportunistic--that is, they occur more frequently in an immune-compromised host. Often, these diseases occur during or after a prolonged course of antibiotic treatment that has killed off the body's natural microflora. There are several opportunistic fungal diseases, but the one with which we are most familiar is candidiasis. This fungus Candida albicans is present on our bodies or within our respiratory tracts all the time, but is kept in check by the presence of bacteria. When skin or mucous membranes are overly moist and air does not circulate around them adequately, candidiasis can result. Examples include vaginitis, diaper rash, or oral candidiasis, known as thrush. Thrush occurs in newborns exposed to high numbers of vaginal fungal hyphae during the birth process. Candida albicans can also be transmitted from the female to the male during intercourse, which can trigger the development of balanitis, or inflammation of the folds of the penis.
A number of fungal-produced toxins are highly poisonous to any consuming organism, and the aflatoxins are among the most deadly. The fungus Aspergillus flavus produces these compounds when growing on peanuts, grains, or nut products. These toxins act at the level of DNA, produce mutations, and are highly carcinogenic. Many animals have become ill or died from eating "moldy" grains. Indeed, people in other countries have greater incidences of cancer because the standards for aflatoxin-tainted grains and nuts are not as stringent as they are in the United States.