Sucrose Fermentation by Brazilian Ethanol Production Yeasts in Media Containing Structurally Complex Nitrogen Sources

Messias Miranda Júnior¹, Margareth Batistote¹, Eduardo Maffud Cilli¹ and José Roberto Ernandes^1,2
¹ Departamento de Bioquímica e Tecnologia Química, Instituto de Química, State University of São Paulo (UNESP), POBox 335, 14801-970 - Araraquara, SP, Brazil.
² Corresponding author. E-mail: ernandes@iq.unesp.br.

J. Inst. Brew. 115(3), 191–197, 2009 | VIEW ARTICLE

ABSTRACT
Four Saccharomyces cerevisiae Brazilian industrial ethanol production strains were grown, under shaken and static conditions, in media containing 22% (w/v) sucrose supplemented with nitrogen sources varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Sucrose fermentations by Brazilian industrial ethanol production yeasts strains were strongly affected by both the structural complexity of the nitrogen source and the availability of oxygen. Data suggest that yeast strains vary in their response to the nitrogen source’s complex structure and to oxygen availability. In addition, the amount of trehalose produced could be correlated with the fermentation performance of the different yeasts, suggesting that efficient fuel ethanol production depends on finding conditions which are appropriate for a particular strain, considering demand and dependence on available nitrogen sources in the fermentation medium.

Key words:
amino acids, anaerobiosis, ethanol production yeasts, nitrogen metabolism, peptides, Saccharomyces, sucrose fermentation, trehalose, yeast.