Combined genomic and transcriptomic analysis of the dibutyl phthalate metabolic pathway in Arthrobacter sp. ZJUTW.

Dibutyl phthalate (DBP) is an environmental pollutant that can threaten human health. The strain Arthrobacter sp. ZJUTW, isolated from the sludge of a river of Hangzhou, can efficiently degrade DBP. Its genomic and transcriptomic differences when cultivated with DBP compared with glucose revealed specific DBP metabolic pathways in the ZJUTW strain. The degrading gene clusters localize separately on a circular chromosome and a plasmid pQL1. Genes related to the initial steps of DBP degradation from DBP to phthalic acid (PA), the pehA gene, and pht gene cluster, are located on the plasmid pQL1. However, the pca gene cluster related to the transforming of intermediate protocatechuic acid (PCA) to acetyl-CoA, is located on the chromosome. After comparative analysis with the reported gene clusters, we found that there were a series of homologous genes in pht and pca gene clusters that contribute to the efficient degradation of DBP by ZJUTW. In addition, transcriptomic analysis suggested a synergistic effect between pht and pca clusters, which also favor ZJUTW allowing it to efficiently degrade DBP. Combined genomic and transcriptomic analyses revealed a complete DBP metabolic pathway in Arthrobacter sp. ZJUTW that is different from that of other reported Arthrobacter strains. After necessary modification based on its metabolic characteristics, Arthrobacter sp. ZJUTW or its derivatives might represent promising candidates for the bioremediation of DBP pollution.