Wide substrate range for a candidate bioremediation enzyme isolated from Nocardioides sp. strain SG-4G.

Abstract

Narrow substrate ranges can impact heavily on the range of applications and hence commercial viability of candidate bioremediation enzymes. Here we show that an ester hydrolase from Nocardioides strain SG-4G has potential as a bioremediation agent against various pollutants which can be detoxified by hydrolytic cleavage of some carboxylester, carbamate or amide linkages. Previously we showed that a radiation-killed, freeze-dried preparation (ZimA) of this strain can rapidly degrade the benzimidazole fungicide carbendazim due to the activity of a specific ester hydrolase, MheI. Here, we report that ZimA also has substantial hydrolytic activity against phthalate diesters (dimethyl, dibutyl and dioctyl phthalate) and anilide (propanil and monalide) and carbamate ester (chlorpropham) herbicides under laboratory conditions. The reaction products are substantially less toxic, or inactive as herbicides, than the parent compounds. Tests of strain SG-4G and Escherichia coli expressing MheI found they were also able to hydrolyse dimethyl phthalate, propanil and chlorpropham, indicating that MheI is principally responsible for the above activities.