菌株A18降解丙烯酰胺的影响因素及其降解产物毒性

Influence factors for the acrylamide degradation by strain A18 and toxicity evaluation for its degradation products

针对前期分离得到的一株丙烯酰胺高效降解菌A18,通过控制接种量,添加碳源、氮源及金属离子等方法,研究了影响该菌降解率的因素.结果表明:当接种量为2.0%～5.0%时,菌株A18的48h降解率达100%;添加碳源(蔗糖、麦芽糖、乳糖和果糖)和氮源(NaNO3,(NH4)2SO4,NH4NO3)均可有效促进降解,但CO(NH2)2对降解率无明显贡献;添加Zn2+,Mn2+可促进降解,添加Cu2+则抑制降解,Ba2+对降解率影响甚小.采用一级动力学模型拟合菌株A18的降解动力学方程,计算出降解速率常数为1.38d-1,丙烯酰胺的半衰期为0.37d.利用费氏弧菌和小新月菱形藻对菌株A18降解丙烯酰胺后产物的毒性进行评价,结果显示降解72h后的产物对费氏弧菌的发光强度和小新月菱形藻的生长均无明显影响,说明其降解产物毒性极弱.

An acrylamide-degrading bacterium A18 was found in preliminary work.In this study,the influence factors of the inoculation amount,carbon source,nitrogen source,and metal ions on strain A18 degradation were examined.The results show that the 48 h degradation rate of A18 reaches 100% with the inoculums of 2.0%~5.0%.Addition of carbon source（sucrose,maltose,lactose,fructose） and nitrogen sources（NaNO3,（NH4）2SO4,NH4NO3） promot the degradation.But no significant contribution is observed by adding CO（NH2）2 as nitrogen source.Zn2＋,Mn2＋ also promot the degradation of acrylamide,while Cu2＋inhibites the degradation process.The first order kinetic model is employed to fit the kinetic equation,from which degradation rate constant is calculated as 1.38 d-1 and half-life（t1/2） as 0.37 days.The luminescence of Vibrio fischeri and the growth of Nitzschia closterium are employed to evaluate the toxicities of the degradation products.The products after 72 h have no significant effect on both the luminescent intensity of Vibrio fischeri and the growth of Nitzschia closterium,which indicates that acrylamide is decomposed into nontoxic products by strain A18.