Screening and Isolation of Esterase-Producing Microorganisms and Optimization of Enzyme Production Conditions from Serratia sp.

Esterases act on a wide variety of natural and xenobiotic compounds which makes them quite useful enzymes in bioremediation. In the present study, fifty-seven bacterial isolates were isolated from soil rich in oil or diesel (automobile workshop), contaminated with plastic wastes, sweet shop waste, garden soil, dairy soil and other soil samples in and around Hamirpur, Shimla and Solan districts of Himachal Pradesh, India. Out of these, the isolate EST-4, which gave maximum esterase activity, was identified as Serratia sp. (NCBI Accession No.: MH538970). Esterase gave considerable activity in PM5 medium containing g/l peptone (10.0, w/v), NaCl (5.0, w/v), beef extract (10.0, w/v), yeast extract (2.0, w/v) and cotton seed oil (1.0%, v/v). Further optimization of various production parameters resulted in maximum production at inoculum age of 18 h, inoculum size 1.0% (v/v), temperature 40 degrees C and pH 8.5. The presence of 1.0% (w/v) maltose, 4.0% (v/v) cotton seed oil and 2.0% (w/v) peptone in the medium enhanced esterase production when compared with other carbohydrate, lipid and nitrogen sources respectively. The enzyme production was enhanced by 2.12-fold after optimization of production parameters.