Mechanistic and analytical understanding of biological immobilization of chromium metal ions from waste-sites

In the proposed study, the isolation, identification and tolerance capacity of chromium (Cr(VI)) resistant fungi collected from different polluted sites of India has been studied. 12 fungal strains (FS1-FS12) have been isolated from the contaminated samples and cultured with different concentrations (100–500 ppm) of Cr(VI) to cumulate new biomasses. Screening and scrutinization divulges FS3 and FS5 isolates to be the most tolerant fungi against the higher concentrations of tested heavy metal with the deduction percentage and uptake of 72.5 ± 0.4%, 73.01 ± 0.12% and 4.30 ± 0.27, 4.39 ± 0.32 mg/g respectively. FS3 and FS5 were identified as Aspergillus flavus and Aspergillus fumigatus by grounding the data of internal transcribed spacer rDNA (ITS) region. The values of correlation coefficients (R²) calculated for A. flavus and A. fumigatus supports the Langmuir isotherm more than that of Freundlich isotherm, thus putting forward the multilayer adsorption of Cr(VI) ions by the mycelium of the fungal strains. Characterization techniques such as Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) has rendered the comparative analysis of biosorbent before and after the removal of Cr(VI) ions, thus substantiating the results of adsorption isotherms. The obtained results have supported the detoxifying potential of both the isolated fungi towards Cr(VI), thus promoting the use of safe biotechnology as one of the sustained recuperative measures.