Isolation, screening and identification of plant growth promoting rhizobacteria to enrich cadmium accumulation in Solanum nigrum L.

Abstract:

[Background] Plant-microbial remediation becomes prevailing in the remediation of soil heavy metal pollution. The key to achieve this is to obtain microorganisms which can interact with hyperaccumulator effectively. Solanum nigrum L. is widely used in the remediation of cadmium pollution of farmland. [Objective] To screen cadmium tolerant plant growth promoting rhizobacteria (PGPR) which can promote the growth and cadmium accumulation of Solanum nigrum L. [Methods] Cadmium tolerant strains with good growth promoting characteristics were isolated and screened from rhizosphere soil of Solanum nigrum L. The effects of cadmium stress on plant growth and cadmium accumulation ability were investigated under hydroponic culture, and microorganism which can promote growth and cadmium accumulation of Solanum nigrum L. was determined. The strain was identified by its physiological and biochemical characteristics and the analysis of its 16S rRNA gene sequence. [Results] Four PGPR strains, NT1, AXY1, AW2 and AW1, were isolated from Solanum nigrum L., which were identified as Lysinibacillus sp., Beijerinckia fluminensis, Achromobacter animicus and Herbaspirillum huttiense. The growth of Solanum nigrum L., was enhanced by four strains, as the increase of height, dry matter accumulation and the cadmium accumulation of the aboveground part. Strain NT1 increased height by 31.33%, and increased the dry weight of the aboveground part by 62.65%. Strain AW2 increased the cadmium accumulation by 37.29%. [Conclusion] Screening of strains can provide a practical basis when it comes to improving the efficiency of plant remediation. It can also help to prepare the ecologically functional bacteria and be used for the microorganism and Solanum nigrum L. combination in situ remediation in the cadmium polluted farmland.