overexpression and characterization of a new organic solvent-tolerant esterase derived from soil metagenomic dna

in this study, an esterase, designated estc23, was isolated from a soil metagenomic library. the protein was amenable to overexpression in escherichia coli under control of the t7 promoter, resulting in expression of the active, soluble protein that constituted 30% of the total cell protein content. this enzyme showed optimal activity at 40 °c and retained about 50% maximal activity at 5–10 °c. estc23 showed remarkable stability in up to 50% (v/v) benzene and alkanes (high log p solvents). when incubated for 7 days in the presence of 50% benzene or alkanes, the enzyme maintained its 2–3 fold elevated activity. the purified enzyme also cleaved sterically hindered esters of tertiary alcohols. these results indicate that estc23 has potential for use in industrial processes.