Aims: To characterize cellulolytic, hydrogen-producing clostridia on a comparable basis. Methods and Results: H2 production from cellulose by six mesophilic clostridia was characterized in standardized batch experiments using MN301 cellulose, Avicel and cellobiose. Daily H2 production, substrate degradation, biomass production and the end-point distribution of soluble fermentation products varied with species and substrates. All species produced a significant amount of H2 from cellobiose, with Clostridium acetobutylicum achieving the highest H2 yield of 2.3 mol H 2 mol-1 hexose, but it did not degrade cellulose. Clostridium cellulolyticum and Clostridium populeti catalysed the highest H 2 production from cellulose, with yields of 1.7 and 1.6 mol H 2mol-1 hexose from MN301 and 1.6 and 1.4 mol H2 mol-1 hexose from Avicel, respectively. These species also achieved 25-100% higher H2 production rates from cellulose than the other species. Conclusions: These cellulolytic, hydrogen-producing clostridia varied in H2 production, with Cl. cellulolyticum and Cl. populeti achieving the highest H2 yields and cellulose degradation. Significance and Impact of the Study: The fermentation of cellulosic materials presents a means of H2 production from renewable resources. This standardized comparison provides a quantitative baseline for improving H2 production from cellulose through medium and process optimization and metabolic engineering.
All Science Journal Classification (ASJC) codes
- Applied Microbiology and Biotechnology