Screening, Optimization Of Fermentation And Enzyme Properties Analysis For Nitrite Reductase

Nitrite is widely exists in the nature, which is a kind of harmful substances and it cancause toxic, carcinogenic and teratogenic. So control of nitrite or nitrate use is very significant.At present, the biological method is the research focus, though nitrite microorganisms canreduce the use of nitrite content.This paper have got a strain producing nitrite reductase strain from South ChinaUniversity of Technology. Through screening and identification,got a strain named Bacillussp C, which can produce high nitrite reductase.Treat Bacillus sp C as the experimental strains and optimized culture mediumcomposition and fermentation conditions, the results as follows: 2.26 % glucose, 0.2 %peptone, NH4 Cl 0.12 %,K2HPO4·H2O 0.2 %,Mg SO4 0.075 %,KCl 0.1 %,Fe SO4 0.004 %,Na NO2 0.2 %. The optimal culture condition: temperature 30 ℃, p H 7,speed 180 r/min, 3 %inoculation quantity. Though optimization the enzyme activity reached 319.43 U/ml,compared before 190.26 U/ml increased by 67.89 %.The reach of characterization of Ni Rs have showed that: the optimal p H is 7.4, at the p H6.6~8.0, the relative enzyme activity in more than 65 %; the optimum temperature is 30 ℃, attemperature below 70 ℃, the residual enzyme activity in more than 70 %; the metal ion havea strong effect on reductase. The results as follows: Mn2+>Mg2+>Na+>Ni2+>K+>Ba2+>Zn2+, especially the Mn2+ has the strongest activation function, the enzyme activity increased57%, inhibitory effect of size on enzyme activity were Fe2+>EDTA>Cu2+>Co2+, especiallyFe2+ has the strongest inhibition, enzyme activity was reduced by 52 %.