Biological treatment of tannery wastewater by using salt-tolerant bacterial strains

Abstract Background High salinity (1–10% w/v) of tannery wastewater makes it difficult to be treated by conventional biological treatment. Salt tolerant microbes can adapt to these saline conditions and degrade the organics in saline wastewater. Results Four salt tolerant bacterial strains isolated from marine and tannery saline wastewater samples were identified as Pseudomonas aeruginosa, Bacillus flexus, Exiguobacterium homiense and Staphylococcus aureus. Growth factors of the identified strains were optimized. Tannery saline wastewater obtained from a Common Effluent Treatment Plant (CETP) near Chennai (southern India) was treated with pure and mixed consortia of four salt tolerant bacterial strains. Experiments with optimized conditions and varying salt content (between 2 and 10% (w/v) were conducted. Salt inhibition effects on COD removal rate were noted. Comparative analysis was made by treating the tannery saline wastewater with activated sludge obtained from CETP and with natural habitat microbes present in raw tannery saline wastewater. Conclusion Salt tolerant bacterial mixed consortia showed appreciable biodegradation at all saline concentrations (2%, 4%, 6%, 8% and 10% w/v) with 80% COD reduction in particular at 8% salinity level the consortia could be used as suitable working cultures for tannery saline wastewater treatment.</p

Biocalorimetric and respirometric studies on production of Penicillin G acylase from Bacillus badius pac in E. coli DH5α

An isothermal heat flux biological reaction calorimeter is employed to monitor the production of Penicillin G acylase (PAC) from E. coli DH5α harboring recombinant construct pPROPAC (pET-30b carrying pac gene from Bacillus badius with its own promoter) cultivated in fermentation medium earlier with different flow rates of oxygen. Three oxygen flow rates were studied. At 0.66 vvm (volume of gas per volume of liquid per minute [11-1 min-1]) a maximum enzyme yield of 43 U/ml was achieved with fructose as carbon source. Metabolic heat flow rate profile and heat yields at different levels helped to conclude that the recombinant construct was an obligate aerobic. Oxygen uptake rate correlated well with enzyme activity, biomass growth and heat production rate at exponential and stationary growth phases in optimized conditions. It was observed that metabolic heat, enzyme activity, substrate utilization rate and oxygen uptake rate matched well. The heat yields due to biomass growth, 15.26kJ/g, substrate consumption, 16.52 kJ/g and oxygen uptake, 413.2 kJ/mol led to understanding the process behavior and physiological activity of the organism under study. The results can contribute to scale up studies, possibly

Thermokinetic responses of the metabolic activity of Staphylococcus lentus cultivated in a glucose limited mineral salt medium

Biocalorimetric experiments were performed to investigate the metabolic thermal responses of the halotolerant species Staphylococcus lentus in glucose limited mineral salt medium. Growth factors were optimized in both shaker flask and calorimetric experiments. A limiting value of 5 g/L glucose was found to be the optimum for S. lentus growth. The heat flux profiles, OUR, biomass growth, and substrate depletion profiles were compared to deduce the metabolic activity of S. lentus. Shifts in heat flux due to the shifts in substrate uptake and three distinct phases of growth are noticeable in heat profile curves. Respirogram (OUR) and heat profiles are seen to follow the biomass growth curve. Oxycalorific coefficient is validated with the theoretical studies and those noticed in published literature

Comparative profiles of % COD removal of tannery soak liquor by identified salt tolerant bacterial consortia and tannery sludge

<p><b>Copyright information:</b></p><p>Taken from "Biological treatment of tannery wastewater by using salt-tolerant bacterial strains"</p><p>http://www.microbialcellfactories.com/content/7/1/15</p><p>Microbial Cell Factories 2008;7():15-15.</p><p>Published online 29 Apr 2008</p><p>PMCID:PMC2397378.</p><p></p

Choline-Based Ionic Liquids-Enhanced Biodegradation of Azo Dyes

Industrial wastewaters such as tannery and textile processing effluents are often characterized by a high content of dissolved organic dyes, resulting in large values of chemical and biological oxygen demand (COD and BOD) in the aquatic systems into which they are discharged. Such wastewater streams are of rapidly growing concern as a major environmental issue in developing countries. Hence there is a need to mitigate this challenge by effective approaches to degrade dye-contaminated wastewater. In this study, several choline-based salts originally developed for use as biocompatible hydrated ionic liquids (i.e., choline sacchrinate (CS), choline dihydrogen phosphate (CDP), choline lactate (CL), and choline tartarate (CT)) have been successfully employed as the cosubstrate with <i>S. lentus</i> in the biodegradation of an azo dye in aqueous solution. We also demonstrate that the azo dye has been degraded to less toxic components coupled with low biomass formation