Biohydrogen production from rice mill wastewater using mutated Enterobacter aerogenes

This study presents the biohydrogen production from rice mill wastewater using mutated Enterobacter aerogenes obtained from random mutagenesis of wild E. aerogenes using UV and ethidium bromide (EtBr). The mutants obtained were screened based on sugar utilization efficiency and the best mutant was selected for further studies. Maximum hydrogen production of 1.92 mol H2/mol sugar was observed with EtBr mutant, whereas 1.72 mol H2/mol sugar was observed with UV mutant. Mutant strains showed 25-35% enhanced hydrogen production than wild strain and the optimum initial pH was found to be 7.0. An efficient mutant strain, E. aerogenes RM08, showed improved growth and enzyme production compared to wild strain. The production hydrogenase was confirmed by SDS-PAGE and enzyme sequencing using MALDI-TOF MS. The hydrogen production and growth data obtained were fitted with Modified Gompertz and Logistic equation. The chemical oxygen demand (COD) reduction of 81% was obtained at the end of 60 h of fermentation.