The Consequence of Arsenic Remediation through potential indigenous Rhizospheric Microbes

Abstract

The present study aimed to focus on identifying the potent microbes for the removal of arsenic contamination. In this experiment, microbes were isolated from their natural soil habitat from the catchment area of the Ganga River. Isolation of microbes from serially diluted method and tolerance test was conducted. Screened microbes were in-vitro evaluated for arsenic tolerance with suitable cultural and molecular techniques. In these results, hyper As-tolerant bacteria were selected and identified as a Bacillus flexus based on a 16s rRNA sequencing analytical study (Accession no. MK114625). Isolated bacteria showed arsenic oxidation, strong urea degradation activity, and low phosphate (P) and potassium (K) solubilizing activities. In-vitro arsenic tolerance has been evaluated against its arsenic compounds such as 969 ppm (arsenite), 1266 ppm (arsenate), and 2082 ppm for the combination {As (V) + As (III) (7:3)}.Further, in the experiment, hyper As-tolerant filamentous fungi Aspergillus sp. isolate HKK4 (Accession no. MN809594) was isolated and identified as Aspergillus flevipes. It is found to be capable of resisting up to 1000 ppm of arsenite in the growth medium. Further, an in-vitro As-bioremediation test was conducted. Aspergillus sp. isolate HKK4 removed arsenic from the medium. Additionally, it was tested for phosphate solubilization and production of gaseous arsine also (As-volatilization) during As-removal. The effect of B. flexus and Aspergillus sp. isolates HKK4 with indigenous AM fungi in combination improved the growth performance and reduced the As-stress of T. aestivum under greenhouse conditions. However, these findings are essential steps for As-stress remediation, and we should also recommend further field validations.