title: Optimization of nitrilase production from Alcaligenes faecalis MTCC 10757 (IICT-A3): effect of inducers on substrate specificity.
abstract: Microbial nitrilases are biocatalysts of interest and the enzyme produced using various inducers exhibits altered substrate specificity, which is of great interest in bioprocess development. The aim of the present study is to investigate the nitrilase-producing Alcaligenes faecalis MTCC 10757 (IICT-A3) for its ability to transform various nitriles in the presence of different inducers after optimization of various parameters for maximum enzyme production and activity. The production of A. faecalis MTCC 10757 (IICT-A3) nitrilase was optimum with glucose (1.0%), acrylonitrile (0.1%) at pH 7.0. The nitrilase activity of A. faecalis MTCC 10757 (IICT-A3) was optimum at 35 °C, pH 8.0 and the enzyme was stable up to 6 h at 50 °C. The nitrilase enzyme produced using different inducers was investigated for substrate specificity. The enzyme hydrolyzed aliphatic, heterocyclic and aromatic nitriles with different substitutions. Acrylonitrile was the most preferred substrate (~40 U) as well as inducer. Benzonitrile was hydrolyzed with almost twofold higher relative activity than acrylonitrile when it was used as an inducer. The versatile nitrilase-producing A. faecalis MTCC 10757 (IICT-A3) exhibits efficient conversion of both aliphatic and aromatic nitriles. The aromatic nitriles, which show not much or no affinity towards nitrilase from A. faecalis, are hydrolyzed effectively with this nitrilase-producing organism. Studies are in progress to exploit this organism for synthesis of industrially important compounds.
authors.affiliation: Biotransformation Laboratory, Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad, 500 607, India.
authors.forename: Y V D
authors.initials: YV
authors.lastname: Nageshwar
authors.forename: Gurrala
authors.initials: G
authors.lastname: Sheelu
authors.forename: Rekha Rao
authors.initials: RR
authors.lastname: Shambhu
authors.forename: Hemalatha
authors.initials: H
authors.lastname: Muluka
authors.forename: Nooreen
authors.initials: N
authors.lastname: Mehdi
authors.forename: M Shaheer
authors.initials: MS
authors.lastname: Malik
authors.forename: Ahmed
authors.initials: A
authors.lastname: Kamal
mesh_terms: D000181:Acrylonitrile / Q000378:metabolism*; D042481:Alcaligenes faecalis / Q000201:enzymology*; D000619:Aminohydrolases / Q000096:biosynthesis* / Q000378:metabolism; D055162:Biocatalysis; D018929:Cell Culture Techniques / Q000379:methods; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009570:Nitriles / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D009570:Nitriles; C014356:benzonitrile; D000619:Aminohydrolases; C021867:nitrilase; D000181:Acrylonitrile