Strobilurin fungicides are some of the most heavily used antifungal chemicals in agriculture. However, little is known of their fate in the environment. We have identifi ed bacteria that slowly transform strobilurin fungicides via hydrolysis of a methyl ester group in the toxophore, rendering them non-fungicidal. A carboxypeptidase (subtilisin Carlsberg) was found to have this activity, albeit with low specifi c activity (2.4 ϫ 10 -2 nmol s -1 mg -1 ), and to possess specifi city towards an analog of the fungicidal isomer of commercial strobilurins. Substrate-docking studies using the known structure for subtilisin Carlsberg revealed a plausible explanation for both the activity and isomer specifi city of this class of hydrolase. These fi ndings suggest that the promiscuous strobilurin methyl esterase activity of the subtilisin-like carboxypeptidases may have a role in the environmental fate of the strobilurin fungicides. Biocatal Biotransformation Downloaded from informahealthcare.com by Mcgill University on 11/03/14 For personal use only. 66592. Can J Microbiol 38:75 -80. Kazlauskas RJ, Weissfl och ANE, Rappaport AT, Cuccia LA. 1991. A rule to predict which enantiomer of a secondary alcohol reacts faster in reactions catalyzed by cholesterol esterase, lipase from Pseudomonas cepacia , and lipase from Candida rugosa . The complete genome sequence of the Gram-positive bacterium Bacillus subtilis . Nature 390:249 -256. Ma YT, Chaudhuri A, Rando RR. 1992. Substrate-specifi city of the isoprenylated protein endoprotease. Biochemistry 31: 11772 -11777. Matsumae H, Furui M, Shibatani T. 1993. Lipase-catalyzed asymmetric hydrolysis of 3-phenylglycidic acid ester, the key intermediate in the synthesis of diltiazem hydrochloride. J Ferment Bioeng 75:93 -98. Miyauchi A, Ozawa M, Mizukami M, Yashiro K, Ebisu S, Tojo T, Fujii T, Takagi H. 1999. Structural conversion from non-native to native form of recombinant human epidermal growth factor by Brevibacillus choshinensis . Biosci Biotechnol Biochem 63: 1965 -1969. Momany FA, Rone R. 1992. Validation of the general-purpose quanta(r)3.2/CHARMM(R) force-fi eld. J Comput Chem 13: 888 -900.