Cu-resistant Kocuria sp. CRB15: a potential PGPR isolated from the dry tailing of Rakha copper mine

Abstract

Rhizobacteria may enhance biomass production and heavy metal tolerance of plants under stress conditions. The present study was carried out for isolation of metal-resistant bacteria that can be further utilized for phytoremediation process. A potential metal-resistant strain CRB15 was isolated from rhizospheric region of Saccharum spontaneum that was found to be resistant against Cu (6.29 mM), Zn (3.25 mM), Pb (1.5 mM), Ni (1.25 mM), and Cd (0.25 mM). SEM analysis was performed for evaluation of morphological changes on bacterial isolate. FTIR analysis observed the change in wavenumbers after the addition of Cu. 16S rDNA sequence analysis showed that CRB15 isolate matched best with genus of Kocuria and was named as Kocuria sp. CRB15. The isolate Kocuria sp. CRB15 was a potential plant growth-promoting rhizobacterium as it had a high IAA (46 µg ml−1), P solubilisation (39.37 µg ml−1), ammonia production (30.46 µmol ml−1), and hydrogen cyanide production capacity. Root–shoot elongation assay conducted on Brassica nigra under lab conditions with strain CRB15 demonstrated positive effects of strain CRB15 in root and shoot elongation of Cu-treated seedlings. This study proved the Kocuria sp. CRB15 a potential PGPR for bacterial-assisted phytoremediation.