The Study On The Homogentisate Pathway Of Aromatic Compounds Degradation In Silicibacter Pomeroyi DSS-3~T

Aromatic hydrocarbons, characterized as bio-refractory organic pollutants, are ubiquitous in the environment and some are found to be mutagenic and carcinogenic. Bioremediation has been proved to be an effective, low-cost method addressing such issue. Elucidation of the molecular basis of the biodegradation pathway in microbes will pave the way to the utilization of this process in the bioremediation of related pollution. However, almost all of the previous works which have been performed thus far are based on the bacteria from soil and freshwater. Little work was found to address the aromatic compounds degradation pathway in the marine isolated bacteria. Silicibacter pomeroyi DSS-3T, the marine bacterium used in present work, is a Gram-negative, rod-shaped aerobic bacterium. It belongs to theα-proteobacteria.Bioinformatics analysis showed that there would be several pathways for aromatic coupounds degradation in Silicibacter pomeroyi DSS-3T, one of which was homogentisate pathway, a central catabolic pathway involved in the degradation of L-tyrosine.Five genes encoding the putative enzymes for tyrosine metabolism were cloned, and expressed in E.coli.BL21. Activities assay substantiated the proposed homogentisate pathway for tyrosine degradation in Silicibacter pomeroyi DSS-3T. Phylogenetic tree showed that the tyrosine aminotransferase, 4-hydroxyphenylpyruva- te dioxygenase, homogentisate 1, 2-dioxygenase, maleylacetoacetate isomerase and Fumarylacetoace hydrolase from Silicibacter pomeroyi DSS-3T have highly homologeous to its homolog from Roseobacter, Sulfitobacter and Phaeobacter.