Diversity of Bacterial Communities in Seleniferous Soils and Their Impact on Plant Growth and Selenium Toxicity

The present study aimed to investigate the diversity of bacterial communities in seleniferous soils using Illumina Mi-Seq Next-Generation Sequencing. This study also compared seleniferous soils (SE) with non-seleniferous (NS) soils to evaluate Selenium (Se) impact on microbial communities and soil properties. Metagenomic analysis identified Proteobacteria as the predominant phylum in both environments, with SE soils exhibiting a higher dominance (48%) than NS soils (31%). The most dominant operational taxonomic unit (OTU) across both soil types belonged to the genus Bacillus. Se altered microbial community composition, increasing the abundance of the Bacillaceae family (30%) and Pseudomonadaceae family (25%) compared to NS soil. Bacillus was the dominant genus in the SE environment indicating its tolerance to selenium. Diversity indices indicated that control soils had higher species richness, while SE soils exhibited a more stressed microbial structure. A consortium of bacterial isolates (Proteus terrae Se3, Halopseudomonas formosensis Se5, and Corynebacterium glutamicum Se38) was inoculated in maize plants cultivated in natural seleniferous soils. Plants inoculated with bacterial consortium grew more healthy and had greater biomass in their roots, shoots, and seeds. Bacterial inoculation results in lesser selenium accumulation in the roots, shoots and seeds of maize plants compared to non-inoculated plants. These results suggest that bacterial species from seleniferous soils may be employed as biofertilizers to enhance plant growth and help plants tolerate Se toxicity in seleniferous soils.