Search

In the present work the hydrogenesis in the anaerobic alkalithermophilic bacterium Thermobrachium celere was studied. The impact of several factors on hydrogen production during glucose fermentation was investigated in batch conditions. The optimal hydrogen production occurred at pH 67 °C 8.2 with phosphate buffer concentration of 50 mM. Hydrogen yield reached the highest value of 3.36 mol H 2 /mol glucose when the partial pressure in the gas headspace was reduced. Supplementation of nitrogen sources and iron affected hydrogen production. Under optimized conditions, the maximum H 2 accumulation and H 2 production rate were estimated to be respectively 124.3 mmol H 2 /l culture and 20.7 mmol H 2 /l/h. Considering the efficient and rapid hydrogen evolution, and the ability to grow in extreme environments, T. celere might be a good candidate for biohydrogen production in open (non-sterile) bioprocess system.

Glycerol-based hydrogen production by the halophilic bacteria Halanaerobium saccharolyticum subspecies saccharolyticum and senegalensis was studied as batch experiments. The main metabolites of glycerol fermentation of both strains were hydrogen, carbon dioxide, and acetate. Subspecies saccharolyticum also produced 1,3-propanediol (1,3-PD), butyrate, and ethanol. The highest hydrogen yields were achieved with 2.5 g/l glycerol and 150 g/l salt at pH 7.4 (subsp. saccharolyticum, yield 0.6 mol/mol glycerol) and at pH 7.0 (subsp. senegalensis, yield 1.6 mol/mol glycerol). The hydrogen yield of subsp. senegalensis has potential for practical applications after scale-up and bioprocess optimizations and metabolic engineering after genome-wide sequencing could be applied to improve the yield of subsp. saccharolyticum.