Thermostable nitrilase catalysed production of nicotinic acid from 3-cyanopyridine

摘要: Abstract A thermostable nitrilase produced by the thermophilic bacterium Bacillus pallidus Dac521 catalyzed direct hydrolysis of 3-cyanopyridine to nicotinic acid without detectable formation nicotinamide. The reaction conditions for production were optimized using free bacterial cells. Temperature and pH optima 60°C 8.0, respectively, with no mass transfer limitation at highest cell loading. Under conditions, 100% substrate could be converted a conversion rate 76 nmol/min/mg dry weight. Free cells effective in converting concentrations up 0.3 M intracellular 3-cyanopyridinase stability was increased presence 0.2 M. Both inhibited greater than Cells immobilized calcium alginate beads retained 98% initial activity more resistant inactivation/inhibition nonimmobilized 60°C. Calcium used column bioreactor over 100 h 10 when continuously supplied 0.1 50°C 60°C, respectively. efficiencies bioreactors operated activity, 104 mg (substrate)/g (cells)/h 208 (cells)/h,