Growth characteristics and photofermentative biohydrogen production potential of purple non sulfur bacteria from sugar cane bagasse

Photofermentative biohydrogen production from lignocellulosic waste is a potentially favorable approach for advance biofuel. Using raw sugarcane bagasse (SCB) as the main feedstock, this study resulted in 148-513 ml H-2/l produced by indigenous isolates of purple non sulfur bacteria (PNSB) in batch cultures. The maximum yield of 1.96 mol H-2/moles sugar was achieved at 30 +/- 2.0 degrees C, initial pH 7.0 +/- 0.2 and inoculum size 10% (v/v) in the presence of light intensity 120-150 W/m(2). Glucose and fructose (1.5%) was used as sole carbon source for comparison and 5.94 and 3.19 mol H-2/mole sugar were obtained, respectively. Biohydrogen production of up to 357.3 ml/l at 40 degrees C and 142 ml/l even at 50 degrees C by SS-8 revealed some thermophilic nature of the microorganism. Kinetic study revealed biohydrogen production by an isolate was a biomass concentration associated function. However, improvement of this one pot process can be made through different parameter optimization. The results suggest the possibility of not only avoiding the need for pretreatment and hydrolysate detoxification but also reducing operational cost incurred on illuminating photobioreactors as sunlight, which is prevalent throughout the year in Pakistan.