Evolutionary Relationships of Catabolic Functions in Soil Bacteria
Within the microbial world, soil bacteria demonstrate a unique metabolic versatility for degradation of a variety of aromatic compounds. The major aromatic pathways discovered in bacteria revealed that essentially all compounds are degraded through a variety of enzymatic steps to limited numbers of common intermediates, such as catechols, which are key compounds for further metabolism. The relationships among the different aromatic pathways and gene clusters often reveal evolutionary changes involved in the development of metabolic routes (xcvan der Meer et al., 1992). Such evolution derived from various genetic events. Biphenyl-utilizing bacteria, widely distributed in the natural environment, include both Gram negative and Gram positive strains (xcFurukawa, 1982). The substrate specificities of biphenyl catabolic enzymes are usually very relaxed. Some bph genes (coding for biphenyl catabolism) are very similar in different strains, suggesting that certain bph genes may transfer among soil bacteria (xcFurukawa et al., 1989). On the other hand, other bph genes are highly diversified and greatly rearranged. Toluene-utilizing bacteria are also widely distributed. Toluene can be metabolized by bacteria by different mechanisms, where substituted groups are modified before or after ring-cleavage, depending on the microorganism. In this communication, evolutionary relationships of catabolic function is discussed, focusing on biphenyl-utilizing and toluene-utilizing bacteria.
KeywordsSoil Bacterium Pseudomonas Putida Ferredoxin Reductase Hybrid Enzyme Pseudomonas Pseudoalcaligenes
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