title: Fermentative and growth performances of Dekkera bruxellensis in different batch systems and the effect of initial low cell counts in co-cultures with Saccharomyces cerevisiae.
abstract: Dekkera bruxellensis is a multifaceted yeast present in the fermentative processes used for alcoholic beverage and fuel alcohol production - in the latter, normally regarded as a contaminant. We evaluated the fermentation and growth performance of a strain isolated from water in an alcohol-producing unit, in batch systems with/without cell recycling in pure and co-cultures with Saccharomyces cerevisiae. The ethanol resistance and aeration dependence for ethanol/acid production were verified. Ethanol had an effect on the growth of D. bruxellensis in that it lowered or inhibited growth depending on the concentration. Acid production was verified in agitated cultures either with glucose or sucrose, but more ethanol was produced with glucose in agitated cultures. Regardless of the batch system, low sugar consumption and alcohol production and expressive growth were found with D. bruxellensis. Despite a similar ethanol yield compared to S. cerevisiae in the batch system without cell recycling, ethanol productivity was approximately four times lower. However, with cell recycling, ethanol yield was almost half that of S. cerevisiae. At initial low cell counts of D. bruxellensis (10 and 1000 cells/ml) in co-cultures with S. cerevisiae, a decrease in fermentative efficiency and a substantial growth throughout the fermentative cycles were displayed by D. bruxellensis. Due to the peculiarity of cell repitching in Brazilian fermentation processes, D. bruxellensis is able to establish itself in the process, even when present in low numbers initially, substantially impairing bioethanol production due to the low ethanol productivity, in spite of comparable ethanol yields.
authors: Departamento de Tecnologia Agroindustrial e Sócio-Economia Rural, Centro de Ciências Agrárias, Universidade Federal de São Carlos, Araras, São Paulo State, Brazil, 13600-970.
authors: Maria Cristina
authors: MC
authors: Meneghin
authors: Ana Paula Guarnieri
authors: AP
authors: Bassi
authors: Carolina Brito
authors: CB
authors: Codato
authors: Vanda Renata
authors: VR
authors: Reis
authors: Sandra Regina
authors: SR
authors: Ceccato-Antonini
mesh_terms: D061249:Batch Cell Culture Techniques; D018920:Coculture Techniques; D055167:Dekkera / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D007218:Industrial Microbiology; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism
chemical_list: D000431:Ethanol; D013395:Sucrose; D005947:Glucose
keywords: Dekkera, Saccharomyces; batch fermentation; co-cultures; contaminant yeasts; ethanol