Temperature-sensitive glucose fermentation in the obligately psychrophilic yeast Candida gelida.

Abstract

Fermentation of glucose by resting cells and cell-free extracts of the obligate psychrophile Candida gelida was essentially abolished after being heated for 30 minutes at 35 C. A survey of the enzymes of the yeast alcoholic fermentation pathway revealed that pyruvate decarboxylase was the only temperature-sensitive enzyme. Kinetic studies of thermal inactivation showed that C. gelida pyruvate decarboxylase was 50% inactivated after it was heated for 10 minutes at 35 C. Restoration of glucose fermentation rate in heated extracts from C. gelida, after addition of purified yeast pyruvate decarboxylase, confirmed that heat-induced loss of fermentative activity was due to inactivation of a temperature-sensitive pyruvate decarboxylase.