Physiological difference during ethanol fermentation between calcium alginate-immobilized Candida tropicalis and Saccharomyces cerevisiae

Calcium alginate-immobilized Candida tropicalis and Saccharomyces cerevisia e are compared for glucose fermentation. Immobilized C. tropicalis cells sh owed a slight morphological alteration during ethanol production at 40 degr eesC, but their fermentation capacity was reduced by 25%. Under immobilizat ion conditions, the two species demonstrated two different mathematical pat terns when the relationship between growth rate, respiration rate, and etha nol tolerance was assessed. The interspecific difference in behavior of imm obilized yeast cells is mainly due to their natural metabolic preference. T he production Of CO2 by calcium alginate-immobilized C tropicalis, as well as the lower supply of oxygen to the cells, are the major factors that redu ce ethanol production. (C) 2001 Federation of European Microbiological Soci eties. Published by Elsevier Science B.V. All rights reserved.