Identification and characterization of a novel esterase from Thauera sp.

A novel esterase gene TLip was identified from the strain Thauera sp. and expressed at high levels in Escherichia coli. The TLip protein shared the highest identity (48%) to esterase TesA from Pseudomonas aeruginosa when compared to enzymes with reported properties. Phylogenetic analysis showed that TLip belongs to the GDSL family of bacterial lipolytic enzymes. TLip was an alkaline esterase with a broad optimal temperature range 37-50 degrees C and an optimal pH of 8.0. Substrate specificity assays showed that TLip preferred medium chain p-nitrophenyl esters (C-6-C-12). Besides, the activity of TLip was strongly inhibited by Cu2+ but greatly enhanced by Triton X-100 and Tween 80. Thermostability assay revealed that TLip was stable without loss of activity at 37 degrees C and still retained 69% activity at 50 degrees C after 2 H of incubation. Together, these provided a good candidate for further exploration of TLip as a promising biocatalyst in industry.