Chapter 12 : The Extent of Microbial Catalysis and Biodegradation: Are Microbes Infallible?

Abstract:

It is often speculated that every non-polymeric compound conceived of by humans and occurring in nature will be metabolized by some microorganism somewhere in the soil or water of the Earth. Is this true? Can it be studied systematically? This chapter provides answers to these questions. The beginnings of an answer are first addressed with existing knowledge. Then, ideas are presented as to how the far reaches of microbial metabolism can be further identified. This effort is also linked to the widespread enterprise of microbial functional genomics. The total extent of genomic diversity is unknown, but comparative genomic analysis to date suggests that genetic diversity in prokaryotes is greater than previously anticipated. This, along with other evidence presented in the chapter, suggests that there is much catalytic diversity yet to be discovered. In the wealth of catalytic diversity possessed by microbial enzymes, two issues are relevant. First, it is unlikely that we have uncovered all of the catalytic potential of these known cofactors. Moreover, it is unclear how many new cofactors, metals, and modified amino acids remain to be discovered in microbial systems. To determine the potential for microbes to transform the exotic compounds for which metabolism is unknown, several compounds containing such functional groups were put into standard enrichment cultures in which the compounds were used as sole carbon or nitrogen sources to support growth. Most of these yielded actively growing cultures of microorganisms, and the target compound was transformed in the cultures, as demonstrated by high-pressure liquid chromatography.