Ethanol production from grass by Thermoanaerobacter B2 isolated from a hot spring in Iceland

摘要

The ethanol production capacity from sugars and timothy (Phleum pratense) hydrolysates by Thermoanaerobacter strain B2 was studied in batch cultures. The strain converts various carbohydrates to ethanol (major product), acetate, hydrogen and carbon dioxide (minor). Maximum ethanol yields were 1.50 mol ethanol mol~(-1) glucose and 1.32 mol ethanol mol~(-1) xylose. A stepwise increase in initial glucose concentrations (5-20 mM) led to proportional increases in ethanol production and complete glucose degradation. At >20 mM glucose concentration, incomplete degradation occurred and end-product formation levelled off. Ethanol production from timothy was investigated. Ethanol yields of untreated timothy hydrolysates resulted in 1.7 mM g~(-1) but were increased by using acid pre-treatment to 4.2 mM g~(-1).