For example, 4.13 mol H2/mol glucose could be produced by using an immobilized co-culture of C. butyricum + Rhodopseudomonas faecalis RLD-5, a combination of a dark - and a photo -fermentative bacterial strain (Ding et al., 2009).But compared to dark fermentation, biohydrogen production via photo-fermentation is a complicated process as it includes complex nutritional and light requirements for suitable growth of the bacteria besides the necessity of strict control of the environmental conditions and substrate (VFA and NH+4 ) inhibitions (Ozmihci and Kargi, 2010).