Enhancing biological hydrogen production through complementary microbial metabolisms

Hydrogen (H-2) production through biological routes is an eco-friendly process. Dark-fermentative or photosynthetic pathways have been widely studied to produce H-2. In these cases yields up to 3.8 mol H-2/mol glucose have been reported to be produced under dark-fermentative conditions by Enterobacter, Caldicellulosiruptor and Thermotoga spp., or through photo-fermentative route by bacteria such as Rhodopseudomonas spp. A combination of the two systems allows a 2-fold increase in H-2 yield. The need is to increase the efficiency of the whole process to yield 12 mol H-2/mol glucose. In this review, we propose that metabolic activities of bacteria may be complemented to use biowaste as feed for increasing the efficiency of H-2 production process. Further utilization of intermediates of these two processes for polyhydroxyalkanoate and methane production is likely to increase the feasibility of meeting the ever increasing energy demand. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.