Minimal medium optimization for soluble sulfate removal by tailor-made sulfate reducing bacterial consortium

Abstract

Modified medium DSMZ 641 used for the growth of SRB consortium developed in the laboratory through enrichment of soil slurry from wastewater fed aquaculture pond at Kolkata India, contained various components that added to the Chemical Oxygen Demand of the solution, making large scale operations using this consortium non-viable. The minimal medium optimization study was carried out using a "one at a time" approach analyzing sulfate reducing ability of the consortium. The consortium reduced soluble sulfate concentration by 70 and 78% (starting from an initial concentration of 2000–3000 mg/L) under suspended and immobilized states, respectively, in 50 mL working volume. The process upon scaling up to 9 L in a vertical biofilm reactor under batch mode could reduce sulfate from the optimized medium by 76% in 4 h, while the same in modified DSMZ 641 was 74%. Response Surface Methodology revealed the optimum concentration of Carbon (Lactic Acid), Nitrogen (Yeast Extract, Ammonium Chloride), and Phosphorus (Potassium Phosphate) in the medium to be 6 mL/L, 500 mg/L each and 750 mg/L respectively.

Keywords:

• Bioremediation
• minimal medium optimization
• one at a time approach
• response surface methodology
• sulfate reducing bacteria

Acknowledgements

Authors acknowledge the financial assistance of the Ministry of Human Resource Development, Government of India under the Frontier Area of Science and Technology Scheme (F.No 5-1/2014-TS.VII dt 7^th Aug 2014). They acknowledge the laboratory facility provided by Maulana Abul Kalam Azad University of Technology, West Bengal, India, while Tripura University provided the computational facility. For Environmental Scanning Electron Microscopy, the authors would like to thank Carl Zeiss facility at Centre for Research in Nanoscience and Nanotechnology, Salt Lake campus, Calcutta University, India.