Implication of highly metal-resistant microalgal-bacterial co-cultures for the treatment of simulated metal-loaded wastewaters.

Microalgal-bacterial co-cultures were employed for the treatment of artificially prepared metal-rich wastewaters in this study. For the purpose, highly metal-resistant microalgal and bacterial species were isolated from a leading wastewater channel flowing through Lahore, Pakistan, and characterized at the molecular level. The microbial identities were proved after BLAST analysis. The microalgal (Chlorella vulgaris-BH1) and bacterial (Exiguobacterium profundum-BH2) species were then co-cultured in five different proportions. Five different proportions of potentially mutualistic microbial co-cultures (comprising of microalgal to bacterial cells in ratios of 1:3, 2:3, 3:3, 3:1, and 3:2) prepared thus were employed to remediate artificially prepared metal-loaded wastewaters. Three randomly selected toxic metals (Cu, Cr, and Ni) were used in this study to prepare metal-rich wastewaters. The microalgal-bacterial co-cultures were then exposed independently to the wastewaters containing 100 ppm of each of the above mentioned metals. The inoculated wastewaters were incubated maximally for a period of 15 days. The metal uptake was noted periodically after every 5 days. The results of the present study depicted that maximally about 78.7, 56.4, and 80% of Cu, Cr, and Ni were removed, respectively after an incubation period of 15 days. The microbial co-culture consisting of microalgal to bacterial cells in a ratio of 3:1 showed the highest remedial potential. The findings of the present study will be helpful in developing effective microalgal-bacterial consortia for economical, efficient, and environment-friendly rehabilitation of the polluted sites.