Biotechnology, General Biochemistry, Genetics and Molecular Biology
16
Scopus Publications
Scopus Publications
Biological diversity of carbon assimilation among isolates of the yeast Dekkera bruxellensis from wine and fuel-ethanol industrial processes Jackeline Maria da Silva, Gilberto Henrique Teles Gomes da Silva, Denise Castro Parente, Fernanda Cristina Bezerra Leite, Carolina Santos Silva, et al. FEMS Yeast Research, 2019 Dekkera bruxellensis is considered a spoilage yeast in winemaking, brewing and fuel-ethanol production. However, there is growing evidence in the literature of its biotechnological potential. In this work, we surveyed 29 D. bruxellensis isolates from three countries and two different industrial origins (winemaking and fuel-ethanol production) for the metabolization of industrially relevant sugars. The isolates were characterized by the determination of their maximum specific growth rates, and by testing their ability to grow in the presence of 2-deoxy-d-glucose and antimycin A. Great diversity was observed among the isolates, with fuel-ethanol isolates showing overall higher specific growth rates than wine isolates. Preferences for galactose (three wine isolates) and for cellobiose or lactose (some fuel-ethanol isolates) were observed. Fuel-ethanol isolates were less sensitive than wine isolates to glucose catabolite repression (GCR) induction by 2-deoxy-d-glucose. In strictly anaerobic conditions, isolates selected for having high aerobic growth rates were able to ferment glucose, sucrose and cellobiose at fairly high rates without supplementation of casamino acids or yeast extract in the culture medium. The phenotypic diversity found among wine and fuel-ethanol isolates suggests adaptation to these environments. A possible application of some of the GCR-insensitive, fast-growing isolates in industrial processes requiring co-assimilation of different sugars is considered.
On the catabolism of amino acids in the yeast Dekkera bruxellensis and the implications for industrial fermentation processes Denise Castro Parente, Danielli Batista Bezerra Cajueiro, Irina Charlot Peña Moreno, Fernanda Cristina Bezerra Leite, Will De Barros Pita, et al. Yeast, 2018 In the last years several reports have reported the capacity of the yeast Dekkera (Brettanomyces) bruxellensis to survive and adapt to the industrial process of alcoholic fermentation. Much of this feature seems to relate to the ability to assimilate limiting sources of nutrients, or somehow some that are inaccessible to Saccharomyces cerevisiae, in particular the sources of nitrogen. Among them, amino acids (AA) are relevant in terms of beverage musts, and could also be important for bioethanol. In view of the limited knowledge on the control of AA, the present work combines physiological and genetic studies to understand how it operates in D. bruxellensis in response to oxygen availibility. The results allowed separation of the AA in three groups of preferentiality and showed that glutamine is the preferred AA irrespective of the presence of oxygen. Glutamate and aspartate were also preferred AA in anaerobiosis, as indicated by the physiological data. Gene expression experiments showed that, apart from the conventional nitrogen catabolic repression mechanism that is operating in aerobiosis, there seems to be an oxygen‐independent mechanism acting to overexpress key genes like GAP1, GDH1, GDH2 and GLT1 to ensure adequate anaerobic growth even in the presence of non‐preferential nitrogen source. This could be of major importance for the industrial fitness of this yeast species.
High intracellular trehalase activity prevents the storage of trehalose in the yeast Dekkera bruxellensis F.C.B. Leite, D.V.da R. Leite, L.F. Pereira, W. de Barros Pita, M.A. de Morais Letters in Applied Microbiology, 2016 Dekkera bruxellensis hit the spotlight in the past decade mostly due to its rather high ability to adapt to several different fermentation processes. This yeast relies on different genetic and physiological aspects to achieve and preserve its high industrial fitness and some of these traits are shared with Saccharomyces cerevisiae. We have previously described that D. bruxellensis is unable to make use of accumulating trehalose as a strategy for cell adaptation and survival in the industrial scenario, as opposed to S. cerevisiae. Since trehalose is often involved in mechanisms related to cell protection, we aimed to investigate both cause and effect of the absence of this metabolite in the cell adaptive capacity in the industrial environment. Our results indicate that the major cause for the nonaccumulation of trehalose is the high constitutive activity of neutral trehalase. Therefore, the rate of trehalose degradation could be higher than its rate of synthesis, preventing accumulation. Altogether, our data elucidate the mechanisms involved in the lack of trehalose accumulation in D. bruxellensis as well as evaluates the implications of this feature.
Distribution of Dekkera bruxellensis in a sugarcane-based fuel ethanol fermentation plant T.C.D. da Silva, F.C.B. Leite, M.A. De Morais Letters in Applied Microbiology, 2016 We investigated the presence of the yeast Dekkera bruxellensis in samples collected at three points surrounding the industrial alcoholic fermentation plants of two distilleries where there are often cases of contamination caused by this yeast: this involved sugar cane wash water, feeding sugar cane juice and vinasse from the treatment pond. Total yeast was isolated in WLN medium with bromocresol green and cycloheximide and further selected on the basis of its ability to grow in synthetic medium containing nitrate. Following this, colonies were selected from the distribution on nitrate plates and identified by amplification with species‐specific primers and DNA sequencing of the 26S‐D1/D2 locus. The results showed that D. bruxellensis is introduced through the feeding substrate, which suggests that its cells originated with the harvested cane. Subsequently, its population circulates as a result of the reuse of water for washing the cane, in a continuous re‐inoculation of the plant with yeasts. Furthermore, the yeast population is formed in the vinasse by the addition of wash water into the treatment ponds and then reintroduced to the culture fields by fertigation, so that the process can be renewed in the following season. It is now possible to adopt sanitation procedures that can prevent the entry of the contamination to the fermentation process.
