Soil selenium shapes microbial community structure in cultivated soils: divergent responses of bacterial and fungal assemblages
Abstract
S elenium-rich soils represent a valuable natural resource with critical importance to agriculture and human health. Soil microorganisms play a key role in the biogeochemical cycling of selenium. Characterizing microbial communities in these soils is essential for advancing green agricultural development and improving the utilization efficiency of natural soil selenium resources. In this study, primer pairs 27F/1492R and ITS1F/ITS4R were used to amplify bacterial 16S rRNA genes and fungal internal transcribed spacer (ITS) sequences, respectively, from field-collected cultivated soil samples. Soil bacterial and fungal communities were compared across three selenium concentration levels (0.33, 0.54, and 0.81 mg/kg), and the relationships between community structure and soil physicochemical properties were evaluated. Within the selenium concentration range of 0.33–0.81 mg/kg, bacterial community diversity did not change significantly, whereas fungal diversity increased with selenium concentration. Selenium level also influenced soil microbial community structure, with a more pronounced effect on fungal communities. Specifically, increasing selenium concentration enhanced fungal network complexity but reduced bacterial network complexity, indicating that the distribution of bacterial and fungal taxa is closely linked to soil selenium content. Furthermore, soil nutrient status, selenium speciation, and enzyme activity differentially shaped bacterial and fungal community structures. This study provides detailed insights into how soil selenium influences microbial communities and supports the development of microbe-driven soil remediation strategies and other relevant applications of microbial resources.