Role of water activity and temperature on activity and stability of dried whole cells of Saccharomyces cerevisiae in a continuous solid–gas bioreactor

Abstract

The conversion of gaseous substrates by whole cells represents a new biotechnological concept with applications in gas–solid bioreactor. In this paper, the gas phase continuous production of hexanol from hexanal using dried baker’s yeast ( Saccharomyces cerevisiae) was studied. Influence of temperature and water activity on reaction rate and stability of the biocatalyst was investigated. An increase of one of these parameters induces an increase in the reaction rate associated to a dramatic decrease in half-life time of the biocatalyst. Moreover, efficiency of ethanol, butanol, and pentanol have been compared for regeneration of the cofactor. It has been observed that initial rate of hexanal reduction decreases as the chain length of the alcohol used for regeneration increases. Efficiency in bioconversion ability is linked to the nature of the yeast used as catalyst.