Novel thermophilic bacteria producing nitrile-degrading enzymes

Abstract

Summary: The first known report of the isolation of thermophilic bacteria which produce nitrile-degrading enzymes is presented. One of the strains isolated was studied in detail. Strain Dac521, classified as Bacillus pallidus, was capable of growth on acetonitrile, benzonitrile, propionitrile, acetamide, benzamide and propionamide as the sole carbon and nitrogen source in minimal nutrient media. The strain produced separate aliphatic-nitrile (e.g. acetonitrile)- and aromatic-nitrile (e.g. benzonitrile)-degrading activities. Acetonitrile-degrading activity was produced constitutively and enzyme production was not enhanced by the addition of substrate. Under conditions where benzonitrile was the sole carbon and nitrogen source in minimal nutrient media, acetonitrile-degrading enzyme activity was completely inhibited and benzonitrile-degrading activity was induced. Growth on substrates as sole carbon and nitrogen sources, together with the substrate specificity of cell-free extracts, suggested that acetonitrile and benzonitrile degradation may have occurred via nitrile hydratase and nitrilase pathways, respectively. Both the acetonitrile- and benzonitrile-degrading enzyme systems were significantly more thermostable in whole-cell preparations and cell-free extracts compared to their mesophilic counterparts.

Isolation and Characterization of a Nitrile-Hydrolysing Bacterium Isoptericola variabilis RGT01

“…Presence of simple sugars such as glucose, sucrose, fructose and maltose (final concentration-1.0 %) in MSM increased the growth of I. variabilis, but resulted in diminished nitrile-hydrolysing activity. Glucose and other hexoses are well known to repress microbial enzymes which are responsible for the catabolism of carbon compounds [23]. Whereas, use of carbon sources like lactose, starch, glycerol and sodium acetate lead to no nitrile-hydrolysing enzyme production.…”

A novel aryl acylamidase from Nocardia farcinica hydrolyses polyamide

“…The reaction was carried out at 308C for 60 min and stopped with 32 mL 10% trichloroacetic acid. After centrifugation at 16,000g for 5 min, the released ammonia was determined colorimetrically using the phenol/hypochlorite method (Cramp et al, 1997). Therefore, 100 mL reaction mixture were added to 350 mL hypochlorite solution together with 350 mL phenol reagent.…”

Immobilization of cells with nitrilase activity from a thermophilic bacterial strain

“…To employ more stable enzymes at higher temperatures is very important. There are few reports on thermostable bacterial nitrilases [6]. A variety of methods for the immobilization of microbial cells are known, which simplify catalyst recovery and reuse, improve the resistance of cells to lysis, and increase the stability of the enzyme activity of the immobilized cells and effectiveness of the degradation process.…”