Diversity of nirS and nirK denitrifying bacteria in rhizosphere and non-rhizosphere soils of halophytes in Ebinur Lake Wetland

Abstract

There are few studies on denitrification related to the nitrogen cycle in Ebinur Lake wetland. This study aimed to explore the response of the diversity and composition of denitrifying bacteria to the environmental factors in wetland, so as to obtain more information about the community structure of denitrifying bacteria driven by environmental factors. Using the genes encoding nitrite reductase (nirS and nirK) as molecular markers, we analysed the seasonal changes in the diversity of denitrifying bacteria in halophyte soils by high-throughput sequencing technology. The results showed that the diversity of denitrifying bacteria was higher in July and lower in April, showing seasonal changes. The diversity index of denitrifying bacteria in rhizosphere soil was higher than that in non-rhizosphere soil. The diversity of denitrifying bacteria in the Phragmites australis rhizosphere soil was the highest. The diversity of nirK denitrifying bacteria was higher than that of nirS denitrifying bacteria, but the relative abundance was lower than that of nirS denitrifying bacteria. Three-way ANOVA showed that soil types, vegetation types and season had significant effects on the diversity of denitrifying bacteria. Furthermore, redundancy analysis indicated that nitrate was the environmental factor that significantly affected the community structure of nirS denitrifying bacteria in wetland, and electric conductivity, total nitrogen, ammonium and nitrate were the environmental factors that significantly affected the community structure of nirK denitrifying bacteria. These results provide data basis and theoretical support for the dynamic change of diversity of denitrifying bacteria in wetland.