Springer Online Journal Archives 1860-2000
Process Engineering, Biotechnology, Nutrition Technology
Summary Statistically designed experiments were used to identify variables important in the 7α-dehydroxylation of cholic acid to deoxycholic acid by strains of Clostridium bifermentans in pH-controlled anaerobic fermentation. Deoxycholic acid yields were highest in the presence of 10% CO2 and near pH 7 but were largely unaffected by the strain of organism used, time of bile acid substrate addition, mode of gas delivery, presence of thioglycollate, or the use of OH− ion or HCO 3 − ion for pH control. However, dehydroxylation was enhanced, and the redox potential remained relatively high, when temperatures were low, inoculum size small, and growth inhibitors were present. Deoxycholic acid yields of up to 40% were observed but the formation of 7-ketodeoxycholic acid side product could not be entirely prevented.
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