硫酸粘菌素对土壤反硝化细菌nirS、nosZ基因多样性的影响

Effects of Colistin Sulphate on nirS,nosZ Gene Diversity of Soil Denitrification Bacteria

建立室内的土壤硫酸粘菌素暴露胁迫模型,采用末端限制性片段长度多态性分析(terminal restriction fragment length polymorphism,T-RFLP)技术分析不同浓度硫酸粘菌素残留对土壤反硝化细菌的影响。结果表明,每个处理组nirS、nosZ基因的分类操作单元(Operational Taxonomic Units,OTU)总数均比对照组低,且nirS基因呈现剂量依赖效应;各组优势细菌nirS基因主要集中在10个片段中,nosZ基因主要集中在18个片段中,nirS基因较nosZ基因丰度变化大;多样性指数分析表明,nirS基因Shannon指数在7 d时,高浓度组较对照组差异显著(P<0.05); Simpson指数在各浓度处理组较对照组差异均显著(P<0.05); Pielou指数在7 d、49 d时,高浓度处理组与对照组差异显著(P<0.05); nosZ基因Shannon指数在35 d时,中浓度组与对照组差异显著(P<0.05); 49 d时,低浓度组与对照组差异显著(P<0.05); Simpson指数在21 d、35 d时,低浓度组与对照组差异显著(P<0.05); Pielou指数在各处理组之间差异均不显著(P>0.05)。当药物含量≥5 mg·kg^(-1)时,反硝化细菌的均匀度、群落多样性降低,优势度升高,群落结构特征均发生改变,其中对nirS基因影响显著。nirS基因更适合作为硫酸粘菌素污染的指示基因。

Based on the colistin sulphate exposure experiments,the nirS,nosZ gene diversity of soil denitrification bacteria exposed were analyzed by using the terminal restriction fragment length polymorphism( T-RFLP) methods.The total Operational Taxonomic Units( OTU) of nirS and nosZ gene is lower than that of the control group. Furthermore,the changes of nirS gene diversity were dependent on the dose of colistin sulphate. The nirS genes of dominant bacteria mainly concentrated in 10 segments while nosZ genes in 18 segments in each group. The richness of nir S gene has lager changes than that of nosZ gene. There exist significant differences for the Shannon index of nirS genes between high concentration groups and the control groups on the 7 thday of incubation( P<0.05). On the7 thday,49 thday,there exist significant differences for Pielou index between the high concentration groups and the control group( P<0.05). On the 35 thday,there are significant differences for the Shannon index of nir S gene between the intermediate concentration groups and the control groups( P<0.05). The Simpson index on 21 stday,35 th day for the low concentration groups is significantly different from those of the control group( P<0.05). However,the differences in Pielou index are not significant among each group( P>0.05). When the drug concentration ≥5 mg·kg-1,the evenness and diversity of the soil denitrification bacteria decreased and the community dominance increased simultaneously,which affected the nirS gene significantly. Our results suggested nirS genes were suitable as a reporter gene for colistin sulfate pollution.