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Characterization of a cypermethrin‐degrading Methylobacterium sp. strain A‐1 and molecular cloning of its carboxylesterase gene
Author(s) -
Diegelmann Corinna,
Weber Joachim,
HeinzelWieland Regina,
Kemme Michael
Publication year - 2015
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.201500186
Subject(s) - carboxylesterase , biology , thermus , methylobacterium , biochemistry , esterase , sequence analysis , gene , 16s ribosomal rna , enzyme , thermophile
A novel mesophilic bacterial strain, designated A‐1, was isolated from microbially contaminated biopolymer microcapsules. The bacterium was able to withstand and grow in liquid cultures supplemented with the pyrethroid cypermethrin in concentrations up to 400 mg L −1 . Furthermore, strain A‐1 could use cypermethrin as sole carbon source and could degrade >50% of it in 12 h. Based on phenotypic and chemotaxonomic characterization, and phylogenetic analysis of 16S rRNA gene sequence, the strain A‐1 was identified as Methylobacterium sp., which is the first reported cypermethrin degrader of methylotrophic bacteria. A role for esterase activity in cypermethrin biodegradation was presumed. Therefore, the carboxylesterase gene mse1 was amplified from the Methylobacterium sp. strain A‐1 genome and the resulting 1 kb amplicon cloned into E. coli . Sequence analysis of the mse1 ‐DNA insert revealed an open reading frame of 633 bp encoding for a putative carboxylesterase of 210 amino acid residues with a predicted molecular mass of 22 kDa. The amino acid sequence of the deduced enzyme MsE1 with the catalytic triad Ser 106 , Asp 156 , and His 187 was found to be similar to that of α/β‐hydrolase fold proteins. The active site Ser 106 residue is located in the consensus pentapeptide motif Gly‐X‐Ser‐X‐Gly that is typical of esterases.