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Applied and Environmental Microbiology, November 2005, p. 6831-6837, Vol. 71, No. 11
0099-2240/05/$08.00+0 doi:10.1128/AEM.71.11.6831-6837.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Jose M. Bruno-Bárcena,3,
and
Emilia Matallana1,2*
Departamento Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de Valencia, Apartado 73, E-46100 Burjassot, Spain,1 Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, CSIC, Apartado 73, E-46100 Burjassot, Spain,2 Planta Piloto de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, CSIC, Apartado 73, E-46100 Burjassot, Spain3
Received 11 March 2005/ Accepted 20 July 2005
Physiological capabilities and fermentation performance of Saccharomyces cerevisiae strains to be employed during industrial wine fermentations are critical for the quality of the final product. During the process of biomass propagation, yeast cells are dynamically exposed to a mixed and interrelated group of known stresses such as osmotic, oxidative, thermic, and/or starvation. These stressing conditions can dramatically affect the parameters of the fermentation process and the technological abilities of the yeast, e.g., the biomass yield and its fermentative capacity. Although a good knowledge exists of the behavior of S. cerevisiae under laboratory conditions, insufficient knowledge is available about yeast stress responses under the specific media and growth conditions during industrial processes. We performed growth experiments using bench-top fermentors and employed a molecular marker approach (changes in expression levels of five stress-related genes) to investigate how the cells respond to environmental changes during the process of yeast biomass production. The data show that in addition to the general stress response pathway, using the HSP12 gene as a marker, other specific stress response pathways were induced, as indicated by the changes detected in the mRNA levels of two stress-related genes, GPD1 and TRX2. These results suggest that the cells were affected by osmotic and oxidative stresses, demonstrating that these are the major causes of the stress response throughout the process of wine yeast biomass production.
Present address: Laboratory of Nuclear Dynamics and Genome Plasticity, Curie Institute/CNRS, Paris, France.
Present address: Department of Microbiology and Biomanufacturing Training and Education Center (BTEC), North Carolina State University, Box 7615, Raleigh, NC 27695-7615.
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