Yeast population dynamics of industrial fuel-ethanol fermentation process assessed by PCR-fingerprinting

Abstract

Yeast population used in industrial production of fuel-ethanol may vary according to the plant process condition and to the environmental stresses imposed to yeast cells. Therefore, yeast strains isolated from a particular industrial process may be adapted to such conditions and should be used as starter strain instead of less adapted commercial strains. This work reports the use of PCR-fingerprinting method based on microsatellite primer (GTG)5 to characterize the yeast population dynamics along the fermentation period in six distilleries. The results show that indigenous fermenting strains present in the crude substrate can be more adapted to the industrial process than commercial strains. We also identified new strains that dominate the yeast population and were more present either in molasses or sugar cane fermenting distilleries. Those strains were proposed to be used as starters in those industrial processes. This is the first report on the use of molecular markers to discriminate Saccharomyces cerevisiae strains from fuel-ethanol producing process.

Industrial fuel ethanol yeasts contain adaptive copy number changes in genes involved in vitamin B1 and B6 biosynthesis

“…Studies of the microbiological dynamics of the industrial fermentors revealed a very rapid succession of yeast strains during fuel ethanol fermentations, and consequently the original ''starter'' yeast (usually commercial baker's yeast strains) was completely replaced by other strains in a matter of weeks (Silva-Filho et al 2005;Basso et al 2008). A few highly productive yeast strains then tended to dominate the fermentor during the entire production season, allowing efficient and stable fermentations.…”

Production of Alcoholic Beverage from Ginger: Study of Fermentation Process and Final Product Quality

“…Temperatures above 35°C benefit bacteria multiplication, yeast viability reduction and acidity increase. Industrial strains of S. cerevisiae are typically resistant to high temperatures; however, it may interfere with cell viability when in synergy with the presence of ethanol or a low pH [18].…”

“…When temperature increases, bacterial contamination is favored and yeast becomes more sensitive to ethanol toxicity [18]. This situation leads to higher levels of residual sugars in fermented and hence ethanol yield decreases.…”

Avaliação da Capacidade Fermentativa, Biomassa e Viabilidade Celular de Isolados de Leveduras Selvagens

“…A seleção da levedura adequada para cada tipo de fermentação é uma estratégia importante para garantir uma boa fermentação, assim como para melhorar as características finais do produto. Durante os processos de fermentação industrial, as leveduras passam por diversas formas de stress 2 3 . Portanto a busca de novas espécies de leveduras mais adaptadas aos processos fermentativos é de suma importância, uma vez que estes micro-organismos são os agentes transformadores responsáveis pelas moléculas de etanol um importante produto biotecnológico.…”