초록
The effect of culture parameters on hydrogen production using strain GHL<SUB>15</SUB> in batch culture was investigated. The strain belongs to the genus Thermoanaerobacter with 98.9% similarity to Thermoanaerobacter yonseiensis and 98.5% to Thermoanaerobacter keratinophilus with a temperature optimum of 65-70 <SUP>o</SUP>C and a pH optimum of 6-7. The strain metabolizes various pentoses, hexoses, and disaccharides to acetate, ethanol, hydrogen, and carbon dioxide. However substrate inhibition was observed above 10 mM glucose concentration. Maximum hydrogen yields on glucose were 3.1 mol H<SUB>2</SUB> mol<SUP>-1</SUP> glucose at very low partial pressure of hydrogen. Hydrogen production from various lignocellulosic biomass hydrolysates was investigated in batch culture. Various pretreatment methods were examined including acid, base, and enzymatic (Celluclast<SUP>®</SUP> and Novozyme 188) hydrolysis. Maximum hydrogen production (5.8-6.0 mmol H<SUB>2</SUB> g<SUP>-1</SUP> dw) was observed from Whatman paper (cellulose) hydrolysates although less hydrogen was produced by hydrolysates from other examined lignocellulosic materials (maximally 4.83 mmol H<SUB>2</SUB> g<SUP>-1</SUP> dw of grass hydrolysate). The hydrogen yields from all lignocellulosic hydrolysates were improved by acid and alkaline pretreatments, with maximum yields on grass, 7.6 mmol H<SUB>2</SUB> g<SUP>-1</SUP> dw.