Chapter Overview

Microorganisms contribute in profound ways to the earth’s structure and function, and therefore, to the survival of other life forms.
Microbes also play significant roles in practical endeavors related to agriculture, food production, industrial processes, and waste treatment.
Microorganisms exist in complex ecological associations that include both living and nonliving components of the environment.
Microbes have adapted to specific habitats and niches, from which they derive food, energy, shelter, and other essential components of the biosphere.
Microbes occupy many levels of a community structure, from producers to consumers to decomposers, and they form close partnerships with other microbes, animals, and plants.
The actions of microbes acting as decomposers or mineralizers are primarily responsible for maintaining and cycling the biologically important elements, such as carbon, nitrogen, and phosphorus, that exist only in certain reservoirs.
As energy passes through various levels of an ecosystem, large amounts of it are lost. Fortunately, energy can constantly be replenished, largely through the actions of photosynthetic organisms that convert the sun’s energy into organic compounds.
The soil forms complex ecosystems that support a wide variety of microorganisms, many of which decompose dead organisms and foster the growth of plants.
Aquatic ecosystems are influenced by temperature, sun, geography, and the water cycle interacting to create numerous adaptive zones for microorganisms.
Water quality is greatly dependent on its microbial and chemical content. Water is made safe by treatment methods that remove pathogenic microbes and toxic wastes.
Biotechnology includes the purposeful use of microorganisms to create industrial, agricultural, nutritional, or medical products through a process of fermentation.
Food fermentations are used to make a variety of milk products (cheeses, yogurt), alcoholic beverages (beer, wine, spirits), and pickles.
Foods must be properly handled and preserved through the use of temperature, chemicals, or radiation to protect consumers against various types of food poisoning.
Large-scale industrial fermentations employ microbial metabolism to manufacture drugs, hormones, enzymes, vaccines, and vitamins.

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