Evaluation of hydrogen production by Clostridium strains on beet molasses

Clostridium acetobutylicum DSM 792, C. acetobutylicum DSM 1731 and two newly isolated bacteria defined as the members of genus Clostridium - based on the 16S rRNA analysis and biochemical traits - were characterized with regard to their hydrogen production in media containing increasing beet molasses concentrations. The highest hydrogen yield was observed for C. acetobutylicum DSM 792 with a yield of 2.8 mol H-2 mol(-1) hexose in medium including 60 g L-1 molasses. This bacterium also produced the maximum amount of hydrogen (5908.8 mL L-1) at the same molasses concentration. A slightly lower hydrogen yield was measured for C. acetobutylicum DSM 1731 (2.5 mol H-2 mol(-1) hexose) when grown on 40 g L-1 molasses. The new isolates Clostridium roseum C and Clostridium saccharoperbutylacetonicum PF produced hydrogen with yields of 2.0 mol H-2 mol(-1) hexose at 40 and 60 g L-1 molasses and 2.1 mol H-2 mol(-1) hexose at 40 g L-1 molasses, respectively.