Thermophilic biohydrogen production by an anaerobic heat treated-hot spring culture

Batch experiments were conducted to investigate the thermophilic biohydrogen production using an enrichment culture from a Turkish hot spring. Following the enrichment, the culture was heat treated at 100 °C for 10 min to select for spore-forming bacteria. H₂ production was accompanied by production of acetate, butyrate, lactate and ethanol. H₂ production was associated by acetate–butyrate type fermentation while accumulation of lactate and ethanol negatively affected the H₂ yield. H₂ production was highest in the temperature range from 49.6 to 54.8 °C and optimum values for initial pH and concentrations of iron, yeast extract and glucose were 6.5, 40 mg/l, 4–13.5 g/l, respectively. PCR–DGGE profiling showed that the heat treated culture consisted of species closely affiliated to genus Thermoanaerobacterium.