A green chemical approach for biotransformation of Cr(VI) to Cr(III), utilizing Fusarium sp. MMT1 and consequent structural alteration of cell morphology

• A chromium resistant fungus (JX170375) was isolated from tannery effluent.
• Strain was identified as Fusarium sp. based on morphological and DNA sequencing data.
• Reduction of Cr(VI) to Cr(III) was optimized by pH, temperature and incubation time.
• Structural modification of fungal cell was noticed during chromium exposure by CLSM, AFM and SEM study.
• Down regulation of proteomic profile was observed under chromium stress.

Chromium (Cr) resistant fungal strain capable of reducing toxic hexavalent chromium to non-toxic trivalent form was isolated from tannery effluent. The strain belonged to the genus Fusarium as concluded on the basis of sugar utilization and molecular profiling studies. The Translation Elongation Factor 1-α (TEF) gene sequence of the strain was identified with the accession number JX170375 in NCBI. The biotransformation of Cr(VI) to Cr(III) was optimized by the following physico-chemical parameters: incubation temperature: 25 °C, incubation time: 72 h and initial pH: 5.0. Chromium reduction efficiency of the strain was observed to be 100% in growth medium after 72 h of incubation. Proteomic profiling indicated a number of proteins to be down regulated in the fungal cell on exposure to chromium. Atomic force, confocal laser scanning and scanning electron micrographs revealed enhanced surface roughness index (5.2 ± 0.2 nm to 11.53 ± 0.3 nm), significant swelling and formation of cage like structures on the cell surface induced by the presence of Cr in growth medium. Thus biotransformation of Cr(VI) in industrial waste achieved with the isolated Fusarium sp. MMT1 strain, utilizes a green technique which is immensely beneficial for bioremediation.