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The present study entails the usefulness of thermophilic amidase-producing bacterium in the biotransformation of benzamide to benzohydroxamic acid (BHA). A bacterium Bacillus smithii IIIMB2907 was isolated from a soil sample collected from hot springs of Manikaran, Himachal Pradesh, India. The whole cells of the bacterium displayed versatile substrate specificity by exhibiting significant activity with a diverse range of amides. In addition, amidase from thermophilic bacterium was induced by adding Ɛ-caprolactam in the mineral base media. The optimum temperature and pH of acyltransferase activity of amidase enzyme were found to be 50 °C and 7.0, respectively. Interestingly, half-life (t1/2) of this enzyme was 17.37 h at 50 °C. Bench-scale production and purification of BHA was carried out at optimized conditions which resulted in the recovery of 64% BHA with a purity of 96%. Owing to this, the reported process in the present study can be considered of immense industrial significance for the production of BHA. [ABSTRACT FROM AUTHOR]

Acetohydroxamic acid is a pharmaceutically active metal chelating agent which has various applications in the field of medicine. Current study focuses on the enzymatic synthesis of acetohydroxamic acid catalysed by thermophilic amidase from Bacillus smithii IIIMB2907. Bacterial cells were grown in 7 L fermenter for amidase production and effect of pH, temperature and substrate concentration for the biotransformation of acetamide to acetohydroxamic acid was studied. Batch reaction was also successfully optimized at bench scale with the recovery of ≈ 81% acetohydroxamic acid (purified). [ABSTRACT FROM AUTHOR]

Till date, amidases from halophiles and halotolerant micro-organisms have not been much explored. In the present study, Brevibacterium sp. IIIMB2706 strain was isolated from salt fields of Gujarat, India, using propionitrile as a nitrogen source in the mineral base media and explored for its amidase activity. Amidase from Brevibacterium sp. IIIMB2706 exhibited substrate affinity towards isobutyramide, propionamide and butyramide. The optimum temperature and pH required for its maximum activity was 45 °C and 7.0, respectively. Effect of salt concentration on amidase activity was also studied and maximum activity was observed in presence of 50 g L−1 NaCl with significant activity up to 200 g L−1 NaCl which justifies its halotolerant nature. Various organic solvents compatibility profile showed that the enzyme was highly active in presence of 10% methyl alcohol. Henceforth, halotolerant enzymes may find application in industrial processes where substrate requires organic solvents for solubilization. [ABSTRACT FROM AUTHOR]

Abstract: In this study, enzymatic surface modification of polyacrylonitrile was studied using nitrile metabolizing enzyme of Amycolatopsis sp. IITR 215. During enzymatic treatment of polyacrylonitrile at pH of 5.8 and 7, it was observed that the conversion of cyano group to carboxylic acid at pH 5.8 was three times higher than at pH 7. This difference in enzymatic treatment efficiency was explained by studying the differences in adsorption profiles of nitrile hydratase and amidase on polyacrylonitrile at pH of 5.8 and 7. Adsorption profiles were determined by monitoring the unbound activities of these two enzymes in the supernatant. From the specific activity profiles of bound nitrile hydratase and amidase it was concluded that more specific binding of nitrile hydratase was observed at pH 5.8 as compared to pH 7. In case of amidase, optimum adsorption was obtained at pH 5.8 within 5h whereas in case of pH 7 it was obtained within 20h. Thus at pH 7, sequential adsorption of nitrile hydratase and amidase was observed and this adsorption profile was similar to the Vroman effect reported during plasma protein adsorption at solid–liquid interface. Ideally, specific nitrile hydratase adsorption followed by sequential adsorption of amidase may enhance higher conversion of cyano group to carboxylic acid. [Copyright &y& Elsevier]

Abstract: Strain Amycolatopsis sp. IITR215 was isolated from a sewage sample using polyacrylonitrile powder as the sole nitrogen source. Identification was performed by 16S rDNA analysis. The isolated strain harbored multiple nitrile-metabolizing enzymes having a wide range of substrate specificities. It metabolized nitrile and amide compounds with constitutive enzymes. Studies using an amidase inhibitor showed that hydrolysis of acrylonitrile and acrylamide occurred due to nitrile hydratase and amidase, respectively, while hydrolysis of hexanenitrile was due to the action of either nitrilase or a second nitrile hydratase/amidase system. The inhibitory effects of N-bromosuccinimide and N-ethylmaleimide on enzymes of this culture were also studied and this further indicated the involvement of either a nitrilase or a second nitrile hydratase/amidase system for hydrolysis of hexanenitrile. Interestingly, hexanenitrile hydrolysis exhibited an optimum temperature of 55°C, whereas acrylonitrile and acrylamide hydrolysis showed an optimum temperature of 45°C. The optimum pH was 5.8 for hexanenitrile hydrolysis and 7.0 for acrylonitrile and acrylamide hydrolysis. Hexanenitrile hydrolysis by enzymes of this strain showed better organic solvent tolerance in the presence of alcohols. The maximum enzyme activity of nitrile-metabolizing enzymes was found using media containing isobutyramide as the nitrogen source. This is the first report on constitutive multiple enzymes from the Amycolatopsis genus. [Copyright &y& Elsevier]