Regulation of biohydrogen production by heat-shock pretreatment facilitates selective enrichment of Clostridium sp.

The effect of heat-shock treatment to selectively enrich acidogenic, H-2 producing consortia was investigated for inoculum preparation and to control the process operation. Long term operation (520 days) in suspended-batch mode bioreactors illustrated relative efficiency and feasibility of heat-shock treated consortia (15.78 mol/kg CODR) in enhancing H-2 production (3.31 mol/kg CODR) when compared to parent (control) consortia. On the contrary, substrate degradation was higher in the control operation (xi(COD), 62.86%; substrate degradation rate (SDR), 1.34 kg CODR/m(3)-day) compared to heat-shock operation (xi(COD), 52.6%; SDR, 1.10 kg CODR/m(3)-day). Heat-shock pretreatment has resulted in a marked fermentation pathway shift towards acetic-butyric acid type production. The microbial diversity illustrated dominance in the Clostridia class after applying heat-shock pretreatment. The redox catalytic currents and Tafel analysis strongly support the conclusion of an improved biocatalyst performance after pretreatment with regards to H-2 production. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Ltd. All rights reserved.