Fermentation of D-Xylose to ethanol by bacillus macerans

In the absence of oxygen Bacillus macerans is able to ferment xylose. The principal products are ethanol, formate, CO sub 2, acetone and H sub 2. The yield of ethanol was 61% based on the theoretical value of 0.51 g per g xylose consumed. The cells could grow in the presence of up to 4% (v/v) of added ethanol but the growth rate was already reduced to about 50% by 1% (v/v) of alcohol. Glucose and the pentoses arabinose and xylose were sequentially utilized when initially present as a mixed substrate. Enzymatic studies indicate that xylose was metabolized via the pentosephosphate and Embden-Meyerhof pathways. At an oxygen concentration of 1-2% air saturation 42 g/l xylose were completely fermented within 160 h and 10 g/l ethanol were produced.