Harmless and Beneficial Bacteria far outnumber harmful varieties. 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 soil enrichment with leguminous crops for
preservation by pickling, for fermentation (as in the manufacture of alcoholic beverages, vinegar,
and certain cheeses), for decomposition of organic wastes (in septic tanks, in some sewage disposal
plants, and in agriculture for soil enrichment) and toxic wastes, and for curing tobacco, retting
flax, and many other specialized processes. Bacteria frequently make good objects for genetic study:
large populations grown in a short period of time facilitate detection of mutations, or rare variations.
Most bacteria are heterotrophic, living off other organisms. Most of these are saprobes, bacteria
that live off dead organic matter. The bacteria that cause disease are heterotrophic parasites. There
are also many non-disease-causing bacterial parasites, many of which are helpful to their hosts. These
include the "normal flora" of the human body.
|
