An essential esterase (BroH) for the mineralization of bromoxynil octanoate by a natural consortium of Sphingopyxis sp. strain OB-3 and Comamonas sp. strain 7D-2.
A natural consortium of two bacterial strains ( Sphingopyxis sp. OB-3 and Comamonas sp. 7D-2) was capable of utilizing bromoxynil octanoate as the sole source of carbon for its growth. Strain OB-3 was able to convert bromoxynil octanoate to bromoxynil but could not use the eight-carbon side chain as its sole carbon source. Strain 7D-2 could not degrade bromoxynil octanoate, although it was able to mineralize bromoxynil. An esterase (BroH) that is involved in the conversion of bromoxynil octanoate into bromoxynil and is essential for the mineralization of bromoxynil octanoate by the consortium was isolated from strain OB-3 and molecularly characterized. BroH encodes 304 amino acids and resembles α/β-hydrolase fold proteins. Recombinant BroH was overexpressed in Escherichia coli BL21 (DE3) and purified by Ni-NTA affinity chromatography. BroH was able to transform p-nitrophenyl esters (C2-C14) and showed the highest activity toward p-nitrophenyl caproate (C6) on the basis of the catalytic efficiency value (Vmax/Km). Additionally, BroH activity decreased when the aliphatic chain length increased. The optimal temperature and pH for BroH activity was found to be 35 °C and 7.5, respectively. On the basis of a phylogenetic analysis, BroH belongs to subfamily V of bacterial lipolytic enzymes.
Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University , 210095 Nanjing, People's Republic of China.
Kai
K
Chen
Yuan
Y
Liu
Dong-Mei
DM
Mao
Xiao-Mei
XM
Liu
Shun-Peng
SP
Li
Jian-Dong
JD
Jiang
D000595:Amino Acid Sequence; D020585:Comamonas / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D004950:Esterases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D059013:Microbial Consortia / Q000502:physiology; D008969:Molecular Sequence Data; D009570:Nitriles / Q000378:metabolism*; D010802:Phylogeny; D017510:Protein Folding; D012336:RNA, Ribosomal, 16S; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D042301:Sphingomonadaceae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D009570:Nitriles; D012336:RNA, Ribosomal, 16S; D011994:Recombinant Proteins; C028382:bromoxynil octanoate; D004950:Esterases