Single stage hydrogen production from cellulose through photo-fermentation by a co-culture of Cellulomonas fimi and Rhodopseudomonas palustris

Biohydrogen production from cellulose by a bacterial co-culture is a potentially promising approach for producing bioenergy from a low cost substrate. The use of a cellulolytic bacterium, Cellulomonas fimi, permits cellulose conversion and the in situ production of substrate for growth and hydrogen production by the photosynthetic bacterium Rhodopseudomonas palustris. Response surface methodology (RSM) with a Box-Behnken design (BBD) was used to examine variations in the key parameters: substrate (cellulose) concentration, yeast extract concentration and the microorganism ratio (Rps. palustris/C. fimi). For the co-culture of R. palustris and C. fimi the highest hydrogen production (44 mmol H₂/L) was achieved at the highest substrate concentration (5 g/L); however, the highest hydrogen yield (3.84 mol H₂/mol glucose equivalent) was observed at the lowest cellulose concentration and highest microorganism ratio. High COD removal efficiencies, over 70%, were achieved over a wide range of conditions and were positively affected by the concentration of yeast extract.