The species richness of the Salix viminalis rhizosphere at the Stebnyk tailings storages dependent on supplementation from the Salicornia europaea rhizosphere

Abstract

Manipulating the rhizosphere microbiome to enhance plant stress tolerance is an environmentally friendly technology and a renewable resource to restore degraded environments. Here we considered the Salicornia europaea rhizosphere community, and the ability of the phytoremediation plant Salix viminalis to recruit its beneficial microbiome to mediate the pollution stress at the Stebnyk mine tailings storage. The tailings contain large amounts of brine salts and heavy metals that contaminate the ground water and surrounding areas, changing soil biogeochemistry and causing increased erosion. The species richness of the endophytic bacterial community of S. viminalis roots was assessed based on observed OTUs, Shannon-InvSimpson, and evenness index. Our results show that biodiversity was decreased across the contamination zones and that S. europaea supplementation significantly increased the species richness. Our results also indicate that the number of dominating OTUs was not changed across zones in both S. europaea-treated and untreated bacterial populations, and that the decrease in richness was mainly caused by the low abundance of OTUs. The importance of engineering microbial communities that support the genetic diversity of degraded environments and the challenges with high throughput metabarcoding databases are discussed.