Characterisation of multi-metal resistant Serratia sp. GP01 for treatment of effluent from fertilizer industries

Abstract

The effluent generated from fertilizer plants in Paradeep in the coast of the Bay of Bengal is the major pollutant causing health hazard in the vicinity of the area with respect to plants, animals and microbes. Samples of effluent were found to contain heavy metals (mg L-1): Cr (100), Ni (36.975), Mn (68.673), Pb (20.133), Cu (74.44), Zn (176.716), Hg (5.358) and As (24.287) as analyzed by XRF. Indigenous bacterial strains were screened for chromate and multi-metal resistance to remediate the toxic pollutants. The isolated strain G1 was identified as Serratia sp. through 16S-rDNA sequence homology. Potent strain Serratia sp. GP01 treated with 100 mg L-1 of K2Cr2O7 has shown the efficacy of reducing 69.05 mg L-1 of Cr over 48 h of incubation. Further, presence of chromate reductase gene (ChR) in Serratia sp. confirmed the enzymatic reduction of Cr (VI). SEM-EDX and SEM mapping analysis revealed substantial biosorption of Cr and other heavy metals present in effluent by Serratia sp. GP01. Antioxidant enzymes such as catalase (72.15 U mL-1), SOD (57.14 U mL-1) and peroxidase (62.49 U mL-1) were found to be higher as compared to the control condition. FTIR study also revealed the role of N-H, O-H, C = C, C-H, C-O, C-N, and C = O functional groups of the cell surface of Serratia sp. treated with K2Cr2O7 and effluent from the fertilizer industry. Isolated strain Serratia sp. could be used for the detoxification of Cr (VI) and other heavy metals in fertilizer plant effluent.