Microorganisms play a fundamental role in the global recycling of matter by releasing carbon, nitrogen, phosphorus, and sulfur from an immense variety of complex organic compounds for reuse by living organisms and in generating energy. The ability of the life support systems of the planet to function depends on the activities of these organisms. The spectacular metabolic versatility of prokaryotes and fungi is displayed in the major areas of environmental microbiology examined in this chapter. We examine sewage and wastewater treatment and the degradation of xenobiotics and petrochemicals, and end with a consideration of biomining. Microorganisms, primarily chemolithotrophic prokaryotes, are effective in the bioleaching of low-grade ores and in the removal of toxic heavy metals from the environment.

DEGRADATIVE CAPABILITIES OF MICROORGANISMS AND ORIGINS OF ORGANIC COMPOUNDS

Microorganisms excel at using organic substances, natural or synthetic, as sources of nutrients and energy. These include certain synthetic compounds – detergents, solvents (trichloroethane, toluene, xylenes), and transformer fluids (polychlorobiphenyls) – that seem very different from any natural compounds such an organism would be likely to encounter. The explanation for this remarkable range of degradative abilities is that prior to the advent of humans, microorganisms had already coexisted for billions of years with an immense variety of organic compounds.