Identification and characterization of Clostridium paraputrificum M-21, a chitinolytic, mesophilic and hydrogen-producing bacterium

A strictly anaerobic, mesophilic and chitinolytic bacterial strain, M-21, w as isolated from a soil sample collected from Mie University campus and ide ntified as Clostridium paraputrificum based on morphological and physiologi cal characteristics, and 16S rRNA sequence analysis. C. paraputrificum M-21 utilized chitin and N-acetyl-D-glucosamine (GlcNAc), a constituent monosac charide of chitin, to produce a large amount of gas along with acetic acid and propionic acid as major fermentation products. Hydrogen and carbon diox ide accounted for 65% and 35% of the gas evolved, respectively. The conditi ons for ii batch culture of C. paraputrificum, including pH of the medium, incubation temperature and agitation speed, were optimized for hydrogen pro duction with GlcNAc as the carbon source. The bacterium grew rapidly on Glc NAc with a doubling time of around 30 min, and produced hydrogen gas with a yield of 1.9 mol H-2/mol GlcNAc under the following cultivation conditions : initial medium pH of 6.5, incubation temperature of 45 degrees C, agitati on speed of 250 rpm, and working volume of 50% of the fermenter. The dry ce ll weight harvested from this culture was 2.0 g/l.