Phenotypic Characterization of Yeasts Aiming at Bioethanol Production

Worldwide, the production of bioethanol is derived through first-generation technology, where plants, vegetables, and cereals, that have high levels of sucrose, are fermented by yeast. Brazil, for the production of bioethanol from sugarcane, is among the world’s leading producers. The process for bioethanol production is a complex that involves a variety of environmental factors, resulting in different phenotypic profiles of strain used. It has been evidenced that the interaction between environmental factors and microorganism can influence in the identification of different characteristics of Saccharomyces cerevisiae. Also, the bioethanol is developed by the second and third generations, and new yeast strains may also contribute to the feasibility of production. Successful performance of fermentation depends on the ability of the yeast to deal with a number of factors that occur during the fermentation, such as concentration of sugar, ethanol, nitrogen, pH, resistance to contaminants, stress protein, temperature change, and osmotic pressure

Estudo genômico e transcritômico de isolados selecionados de alto rendimento de dorna de fermentação alcoólica de Saccharomyces cerevisiae

Brazil currently has an estimated production of bioethanol with crop 2013/14 from 27.17 billion liters. This production is derived from a fermentation process of Brazilian sugarcane mills and is characterized today as a semi-continuous process. The yeast Saccharomyces cerevisiae is the most comprehensive in fermentation processes, by being adaptable to different environments, having a rich diversity of phenotypic and genotypic profiles, showing that the interactions between environmental factors and influences in this organism identification of essential and specific features in the fermentative process. The construction of a bank of organisms related to ethanol production is vital to the interests of researchers Bioen UNESP program. Thus, it is fundamental to the existence of a collection of yeast strains with high fermentation potential. In a previous study conducted by our group, were selected from a Brazilian plant two strains (ZFC4 and ZFD4) with potentially differential characteristics in the ethanol production process. Based on these data, the aim of this study was first to analyze genotypic and phenotypic characteristics of strains ZFC4 and ZFD4 to identify functional genetic factors through sequencing DNA and RNA global new generation HiSeq Ilumina and subsequently selected strains were screened for combinations with industry standards (PE-2, CAT and SA-I), aiming at selecting promising synergistic associations in the fermentation process for the alcohol sector. For both the associations of these strains were evaluated for cell growth, assimilation of sugars, tolerance to temperature and ethanol and fermentative capacity. All combinations made between the patterns and ZFC4 and ZFD4 strains were synergistic for all parameters analyzed, especially in relation to resistance to high ethanol concentrations and temperature. Importantly, our lines alone were as effective as the fermentation patterns, however these in combination ...Atualmente o Brasil possui uma estimativa de produção de bioetanol com a safra de 2013/14 de 27,17 bilhões de litros. Esta produção é derivada de um processo de fermentação das usinas sucroalcooleiras brasileiras e caracteriza-se atualmente como um processo semi-contínuo. A levedura Saccharomyces cerevisiae é a mais abrangente nos processos de fermentação, por ser adaptável aos diferentes ambientes, possuindo uma rica diversidade de perfis fenotípicos e genotípicos, evidenciando que as interações entre fatores ambientais e este organismo influenciam na identificação de características essenciais e específicas nos processos fermentativos. A construção de um banco de organismos relacionados com a produção de etanol é indispensável aos interesses de pesquisadores do programa Bioen da UNESP. Assim, é de fundamental importância a existência de uma coleção de linhagens de leveduras, com potencial fermentativo elevado. Em estudo anterior, desenvolvido por nosso grupo, foram selecionadas de uma usina brasileira duas linhagens (ZFC4 e ZFD4) com características potencialmente diferenciais no processo de produção de etanol. Com base nestes dados o objetivo deste estudo foi primeiramente analisar características genotípicas e fenotípicas das linhagens ZFC4 e ZFD4 para identificação de fatores genéticos funcionais por meio de sequenciamento do DNA e RNA global de nova geração Hiseq Ilumina e posteriormente, as linhagens selecionadas foram rastreadas por combinações com os padrões industriais (PE-2, CAT e SA-I), visando à seleção de associações sinérgicas promissoras no processo de fermentação para o setor sucroalcooleiro. Para tanto as associações destas linhagens foram avaliadas quanto ao crescimento celular, assimilação de açucares, tolerância à temperatura e ao etanol e capacidade fermentativa. Todas as combinações realizadas entre os padrões e as linhagens ZFC4 e ZFD4 foram sinérgicas para ...Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Transcriptional profile of a bioethanol production contaminant Candida tropicalis

Abstract The fermentation process is widely used in the industry for bioethanol production. Even though it is widely used, microbial contamination is unpredictable and difficult to control. The problem of reduced productivity is directly linked to competition for nutrients during contamination. Yeasts representing the Candida species are frequently isolated contaminants. Elucidating the behavior of a contaminant during the fermentation cycle is essential for combatting the contamination. Consequently, the aim of the current study was to better understand the functional and transcriptional behavior of a contaminating yeast Candida tropicalis. We used a global RNA sequencing approach (RNA-seq/MiSeq) to analyze gene expression. Genes with significantly repressed or induced expression, and related to the fermentations process, such as sugar transport, pyruvate decarboxylase, amino acid metabolism, membrane, tolerance to high concentrations of ethanol and temperatures, nutrient suppression), and transcription-linked processes, were identified. The expression pattern suggested that the functional and transcriptional behavior of the contaminating yeast during fermentation for bioethanol production is similar to that of the standard yeast Saccharomyces cerevisiae. In addition, the analysis confirmed that C. tropicalis is an important contaminant of the alcoholic fermentation process, generating bioethanol and viability through its tolerance to all the adversities of a fermentation process essential for the production of bioethanol. According on the gene expression profile, many of these mechanisms are similar to those of S. cerevisiae strains currently used for bioethanol production. These mechanisms can inform studies on antimicrobials, to combat yeast contamination during industrial bioethanol production