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A natural consortium comprising of two bacterial strains of Sphingopyxis sp.OB-3 and Comamonas sp.7D-2 was isolated from a bromoxynil octanoate-contaminated soil sample.Strain OB-3 converted bromoxynil octanoate to into bromoxynil and could not use the eight-carbon side-chain as the sole carbon source for growth.Strain 7D-2 did not degrade bromoxynil octanoate, while it mineralized bromoxynil.The consortium was capable of utilizing bromoxynil octanoate or bromoxynil as the sole source of carbon for growth.An esterase (BroH) which is involved in the conversion of bromoxynil octanoate into bromoxynil and essential for the mineralization of bromoxynil octanoate by the consortium, was molecularly characterized in strain OB-3.BroH encodes 304 amino acids and shows the highest similarities to α/β-hydrolase fold proteins.The recombinant BroH was over-expressed in Escherichia coli BL21 (DE3) and purified by Ni-NTA affimity chromatography.BroH was able to transform p-nitrophenyl esters (C2-C14) and showed the highest activity towards p nitrophenyl caproate (C6) based on the catalytic efficiency value (Vmax/Km), and the activities of BroH decreased with the increase of the aliphatic length.The optimum temperature and pH for BroH activity was at 35℃ and 7.5, respectively.Based on the phylogenetic analysis, BroH belongs to the family V of lipolytic enzymes.