PCL depolymerase activity was determined by the modified
method of Park et al. (2007) using p-nitrophenyl butyrate (pNPB) as
chromogenic substrate for esterase assay. This assaywas performed
after every 24 h up to the maximum of 120 h. Stock solution of pNPB
was prepared in acetonitrile. 0.3 mL of culture supernatant was
added to 2 mL buffer along with 25 mL substrate and 10 mL of
ethanol. The reaction mixture was incubated at 37 C for 20 min,
then OD was calculated at 410 nm through spectrophotometer. The
experiment was run in triplicate, a control was run in separate for
each experiment. One unit of enzyme was defined as the amount of
enzyme required to liberate 1 mmole of p-nitrophenol per min.