Effect of co-culturing bacteria and microalgae and influence of inoculum ratio during the biological treatment of tannery wastewater.

This present investigation is carried out to study the effect of algal and bacterial inoculum concentrations on the removal of organic pollutants and nutrients from the tannery effluent by the combined symbiotic treatment process. The bacterial and microalgal consortia was developed in laboratory setup and mixed together to perform this study. The Influence of algae and bacteria inoculum concentrations on the removal of pollutants such as Chemical Oxygen Demand (COD) and Total Kjeldahl Nitrogen (TKN) were studied using statistical optimization through Response surface methodology. For the design of experimental set up and optimization, full factorial Central composite design was used. The profiles of pH, Dissolved Oxygen (DO) and nitrate were also monitored and studied. The inoculum concentrations of microalgae and bacteria showed significant effect on Co-culturing on COD, TKN and nitrate removals as major response. The linear effect of bacterial inoculum has positive dominant influence on COD and TKN removal efficiencies. Nitrate utilization by microalgae increases with the increase in microalgal inoculum concentration. The maximum removal efficiencies of COD and TKN with 89.9% and 80.9% were obtained at optimum bacterial and algal inoculum concentrations of 6.7 g/L and 8.0 g/L respectively. These outcomes of this study are immensely favorable for maximizing the COD and nitrogen (nutrients) removal capabilities of microalgae-bacterial consortia in tannery effluent.

Engineering microbial cells with metal chelating hydroxylated unnatural amino acids for removable of synthetic pollutants from water.

Lead (Pb2+) is a well-known heavy metal and toxic synthetic industrial pollutant in the ecosystem and causes severe threats to living organisms. It is paramount to develop a sustainable microbial engineering approach to remove synthetic pollutants from the environment. Genetic code engineering is emerging as an important microbial engineering tool in biosciences to biosynthesis congener protein production beyond the canonical set of natural molecules and expand the chemistries of living cells. Here, we prepare cells expressing unnatural amino acid encoded congener proteins for effectively removable toxic synthetic industrial pollutants (Pb2+) with high binding efficiency. Native and the developed congener proteins expressing cells adapted the Langmuir and Sips adsorption model that recommends uniform adsorption with Pb2+ ions. This could be due to a more significant number of functional groups on the protein surface. Fluorescence spectroscopic, field emission scanning electron microscope, X-ray photoelectron spectroscopic analysis, and protein-metal molecular stimulation coordination allowed us to explore the role of hydroxylation on Pb2+ adsorption. The bioreactor filled with immobilized protein-containing active granules showed >90% of lead removal in the contaminated water samples. The desorption of bound Pb2+ from GFP and its variants were studied by varying the pH to reuse the proteins for subsequent usage. We observed that about 70% of the GFP and its variants could be recycled and >75% of fluorescence efficiency could be recovered. Among all the variants, GFPHPDP exhibits high affinity and maintains the reusability efficiency in 7 consecutive cycles. These results suggest that genetic code engineering of cells encoding unnatural amino acids could be a next-generation microbial engineering tool for manipulating and developing the microbial strain's selective and effective removal of synthetic pollutants from the environment.