Oxygen-limited cellobiose fermentation and the characterization of the cellobiase of an industrial Dekkera/Brettanomyces bruxellensis strain

Abstract

The discovery of a novel yeast with a natural capacity to produce ethanol from lignocellulosic substrates (second-generation ethanol) is of great significance for bioethanol technology. While there are some yeast strains capable of assimilating cellobiose in aerobic laboratory conditions, the predominant sugar in the treatment of lignocellulosic material, little is known about this ability in real industrial conditions. Fermentations designed to simulate industrial conditions were conducted in synthetic medium with glucose, sucrose, cellobiose and hydrolyzed pre-treated cane bagasse as a different carbon source, with the aim of further characterizing the fermentation capacity of a promising Dekkera bruxellensis yeast strain, isolated from the bioethanol process in Brazil. As a result, it was found (for the first time in oxygen-limiting conditions) that the strain Dekkera bruxellensis GDB 248 could produce ethanol from cellobiose. Moreover, it was corroborated that the cellobiase activity characterizes the enzyme candidate in semi-purified extracts (β-glucosidase). In addition, it was demonstrated that GDB 248 strain had the capacity to produce a higher acetic acid concentration than ethanol and glycerol, which confirms the absence of the Custer effect with this strain in oxygen-limiting conditions. Moreover, it is also being suggested that D. bruxellensis could benefit Saccharomyces cerevisiae and outcompete it in the industrial environment. In this way, it was confirmed that D. bruxellensis GDB 248 has the potential to produce ethanol from cellobiose, and is a promising strain for the fermentation of lignocellulosic substrates.

Assessing Genetic Diversity among Brettanomyces Yeasts by DNA Fingerprinting and Whole-Genome Sequencing

“…␤-Glucosidases are well-known for their role in flavor development in beer and wine (74,75). Additionally, ␤-glucosidase has been shown to play a role in the fermentation of cellobiose by B. bruxellensis (76)(77)(78)(79). Interestingly, we found that ST05.12/22 did contain another ␤-glucosidase gene, which was also present in AWRI 1499 and CBS 2499.…”

Caracterização Dos Perfis De Crescimento Celular De Meyerozyma Caribbica Em Meios De Cultura Contendo Glicose, Xilose E Celobiose

“…Desse modo, alguns pesquisadores veem a engenharia genética dessa levedura como opção para a viabilização da produção de etanol 2G (Stambuk et al, 2008;Lee et al, 2013). Por outro lado, há trabalhos recentes que demonstram a possibilidade do emprego de outras espécies de leveduras nas dornas de fermentação como alternativa à engenharia genética de S. cerevisiae (Reis et al, 2014;Wang et al, 2016).…”

Harnessing improved understanding ofBrettanomyces bruxellensisbiology to mitigate the risk of wine spoilage

“…For example, genome analysis revealed the presence of the entire pathway for chitin assimilation (Curtin et al 2012a), and B. bruxellensis is able to grow on and ferment the cellulose breakdown disaccharide cellobiose (Blondin et al 1982), even under oxygen-limited conditions (Reis et al 2014), such as might be encountered during barrel maturation of wine. For example, genome analysis revealed the presence of the entire pathway for chitin assimilation (Curtin et al 2012a), and B. bruxellensis is able to grow on and ferment the cellulose breakdown disaccharide cellobiose (Blondin et al 1982), even under oxygen-limited conditions (Reis et al 2014), such as might be encountered during barrel maturation of wine.…”

“…Another feature differentiating B. bruxellensis from S. cerevisiae is its capacity to assimilate a wider range of carbon sources. For example, genome analysis revealed the presence of the entire pathway for chitin assimilation (Curtin et al 2012a), and B. bruxellensis is able to grow on and ferment the cellulose breakdown disaccharide cellobiose (Blondin et al 1982), even under oxygen-limited conditions (Reis et al 2014), such as might be encountered during barrel maturation of wine. It is important to note that B. bruxellensis growth is slower on cellobiose than on simple reducing sugars, and that similar to nitrate utilisation, cellobiose assimilation varies among B. bruxellensis strains (Conterno et al 2006).…”