去除低温地下水中硝酸盐适冷反硝化菌的筛选与特征研究

Study on the isolation and characteristics of cold-adaptive denitrifying bacteria to remove nitrate from groundwater at low temperature

硝酸盐氮是地下水中常见的污染物之一,由于地下水水温通常低于15℃,尤其是黑龙江省地下水温普遍在6~10℃,严重影响地下水生物处理工艺中的反硝化效率。本文从低温地下水中筛选出可在0~40℃生长的适冷反硝化菌Y39-6,其表型、生理生化和基因特征表明,Y39-6与极地假单胞菌(Pseudomonas extremaustralis)高度同源。菌株Y39-6可以利用NO^-_3-N为唯一氮源进行生长,在0.5 h内反硝化速率最大,为99.04 mg·L^-1·h^-1;72 h内对硝酸盐的最大去除率可达88.82%。10℃条件下,Y39-6的反硝化动力学方程与莫诺方程拟合度R^2=0.930,动力学参数μ_(max)=0.44 h^-1,半饱和常数K_s=119.517 mg·L^-1。温度、pH值、溶解氧(DO)和C/N比影响菌株Y39-6对硝酸盐的去除效率,当温度为15℃、pH值7.2、DO为10~12 mg·L^-1(摇床转速为180 r·min^-1)、C/N比为10时,菌株Y39-6对硝酸盐的去除率最高(63.00%)。本研究结果为低温地下水除硝酸盐提供了菌种资源和理论依据。

Nitrate is one of common pollutants existing in groundwater.The temperature of groundwater is normally lower than 15℃.Especially in Heilongjiang Province,it is commonly as low as 6~10℃,which seriously affects the denitrifying efficiency of biological process used in groundwater treatment.In this study,cold-adaptive denitrifying bacterium,the strain Y39-6 was isolated from groundwater and could grow at 0~40℃.The phenotypic,biological,chemical and genetic characteristics of the strain Y39-6 showed high homology to Pseudomonas extremaustralis.The strain Y39-6 could utilize nitrate as sole nitrogen source to grow.In 0.5 h,its denitrifying rate was the highest to 99.04 mg·L-1·h-1.In 72 h,the highest nitrate removal rate could reach to 88.82%.The denitrifying kinetics of the strain Y39-6 was fitting with Monod equation with R2=0.930 at 10℃.The kinetic parametersμmax was 0.44 h-1 and Ks was 119.517 mg·L-1.Temperature,pH,dissolved oxygen(DO)and C/N ratio affected the nitrate removal efficiency of the strain Y39-6.When the temperature was 15℃,pH was 7.2,DO was 10~12 mg·L-1(shaking speed of 180 r·min-1),and C/N ratio was 10,the nitrate removal efficiency of the strain Y39-6 was the highest(63.00%).Results of this study proposed a bacterial resource and theoretical support for nitrate removal from groundwater.