ABSTRACT
The culled apple juice contained (% w/v): nitrogen, 0.036; total sugars, 11.6 and was of pH 3.9. Saccharomyces cerevisiae NCIM 3284, Pichia kluyeri and Candida krusei produced more ethanol from culled apple juice at its optimum initial pH 4.5, whereas S. cerevisiae NCIM 3316 did so at pH 5.0. An increase in sugar concentration of apple juice from natural 11.6% to 20% exhibited enhanced ethanol production and improved fermentation efficiency of both the S. cerevisiae strains, whereas P. kluyveri and C. krusei produced high ethanol at 11.6% and 16.0% sugar levels, respectively. Urea was stimulatory for ethanol production as well as fermentation efficiency of the yeast strains under study.
Subject(s)
Beverages/microbiology , Candida/metabolism , Ethanol/metabolism , Fermentation , Pichia/metabolism , Rosales , Saccharomyces cerevisiae/metabolismABSTRACT
Side-chain cleavage of sterol and extracellular cholesterol oxidase activity were investigated using viable cells of R. equi DSM 89-133 immobilized in polyacrylamide gel. In batch culture, immobilized cells were active in side-chain cleavage of cholesterol for more than 30 days. Free or immobilized cells were incapable of side-chain cleavage in the absence of 2,2' dipyridyl; cholesterol oxidase was, however, produced in both the cases. Maximal activity of the immobilized cells was 60 to 70% of the free cells.