AMicroorganisms have evolved a wide variety of strategies for the biodegradation of natural and synthetic chemicals. The synthetic chemicals have only been in the biosphere for the past century- yet most simple synthetic organic compounds are now biodegradable in spite of the presence of halogens, nitro groups, and other substituents.

In many instances the enzymes involved in the catabolic pathways are closely related to the enzymes involved in degradation of natural compounds. In other instances the origin of the genes is unknown. There is a huge reservoir of unexplored metabolic diversity among bacteria that degrade natural organic compounds. The catabolic pathways appear to have provided the basis for evolution of pathways for degradation of synthetic organic compounds. Exploration of the catabolic pathways for natural compounds will provide insight about how pathways evolve in nature and will provide genes that can be exploited for applications in biocatalysis for green chemistry. 3-Nitrotyrosine is a natural organic compound widely produced in plants and animals. Ongoing investigation of the degradation pathways and ecological roles of bacteria that degrade 3-nitrotyrosine will illustrate how discovery of such pathways can reveal previously unknown metabolic diversity and identify unknown open reading frames among sequenced genomes.

The metabolic diversity of bacteria that degrade synthetic organic compounds can be harnessed for synthesis of chemicals that are difficult to produce by traditional organic chemistry. The enzymes involved in biodegradation of nitrobenzene, for example, have been used as biocatalysts for synthesis of a variety of aminophenols. The enzymes can be assembled in E. coli, immobilized in silica, or packed in microfluidic devices to provide synthetic routes not readily accessible by organic chemistry.