A New Nitrilase-Producing Strain Named Rhodobacter sphaeroides LHS-305: Biocatalytic Characterization and Substrate Specificity

Abstract

The characteristics of the new nitrilase-producing strain Rhodobacter sphaeroides LHS-305 were investigated. By investigating several parameters influencing nitrilase production, the specific cell activity was ultimately increased from 24.5 to 75.0 μmol g(-1) min(-1), and hereinto, the choice of inducer proved the most important factor. The aromatic nitriles (such as 3-cyanopyridine and benzonitrile) were found to be the most favorable substrates of the nitrilase by analyzing the substrate spectrum. It was speculated that the unsaturated carbon atom attached to the cyano group was crucial for this type of nitrilase. The value of apparent K (m), substrate inhibition constant, and product inhibition constant of the nitrilase against 3-cyanopyridine were 4.5 × 10(-2), 29.2, and 8.6 × 10(-3) mol L(-1), respectively. When applied in nicotinic acid preparation, the nitrilase is able to hydrolyze 200 mmol L(-1) 3-cyanopyridine with 93% conversion rate in 13 h by 6.1 g L(-1) cells (dry cell weight).

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

“…Acetonitrile was finally chosen as the inducer for the cultivation, due to its cheaper price and good effectivity than other inducers. It was found to act as an efficient inducer for nitrilases of Pseudomonas putida [5] and Rhodobacter sphaeroides [21]. MSM supplemented with 50 mM acetonitrile, an incubation temperature of 30°C with 2 % v/v inoculum, at 200 rpm and incubation of 48 h was found to be the optimal condition for maximum production (2.64 ± 0.12 U/mg) of nitrile-hydrolysing activity by I. variabilis RGT01 (Fig.…”

Application of Response Surface Methodology and Plackett Burman Design assisted with Support Vector Machine for the Optimization of Nitrilase Production by Bacillus subtilis AGAB-2

“…Similar results have also been reported by Duca et al (2014) [33] for the production of nitrilase by Pseudomonas sp. strain UW4 and Yang et al (2011) [34] with Rhodobacter spheroids LHS-305. The maximum nitrilase activity obtained was 1839.13 ± 13.30 U/ml with acrylonitrile as the inducer, without any carbon source.…”

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“…The 3-cyanopyridinase of Bacillus sp. MTCC 7545 also degrade benzonitrile and propionitrile(carcinogenic substances) at high temperature though some reported studies showed hydrolysis at ambient temperature 31,32 . From the double reciprocal plot, the calculated K m and V max were 0.…”