Ethanol production from Dekkera bruxellensis in synthetic media with pentose

Abstract

Ethanol is obtained in Brazil from the fermentation of sugarcane, molasses or a mixture of these. Alternatively, it can also be obtained from products composed of cellulose and hemicellulose, called "second generation ethanol-2G". The yeast Saccharomyces cerevisiae, commonly applied in industrial ethanol production, is not efficient in the conversion of pentoses, which is present in high amounts in lignocellulosic materials. This study aimed to evaluate the ability of a yeast strain of Dekkera bruxellensis in producing ethanol from synthetic media, containing xylose or arabinose, xylose and glucose as the sole carbon sources. The results indicated that D. bruxellensis was capable of producing ethanol from xylose and arabinose, with ethanol concentration similar for both carbon sources, 1.9 g L-1. For the fermentations performed with xylose and glucose, there was an increase in the concentration of ethanol to 5.9 g L-1 , lower than the standard yeast Pichia stipitis (9.3 g L-1), but with similar maximum yield in ethanol (0.9 g g TOC-1). This proves that the yeast D. bruxellensis produced lower amounts of ethanol when compared with P. stipitis, but showed that is capable of fermenting xylose and can be a promising alternative for ethanol conversion from hydrolysates containing glucose and xylose as carbon source.

Fermentation profiles of the yeast Brettanomyces bruxellensis in d‐xylose and l‐arabinose aiming its application as a second‐generation ethanol producer

“…Additionally, we tested whether a higher sugar concentration ( d ‐xylose at 40 g/L) and a longer period of fermentation (96 h) could influence the fermentative capacity of B. bruxellensis. Nonetheless, changing these parameters did not enhance the performance of our strains (data not shown), unlike a previous work with different B. bruxellensis isolates (Codato et al, 2018). In fact, although many yeast species are able to assimilate d ‐xylose, few are competent to natively ferment this sugar to ethanol (Rodrussamee et al, 2018).…”

“…In order to test the capacity of B. bruxellensis to ferment d ‐xylose and l ‐arabinose in a scenario closer to that found in the industrial environment, we carried out fermentation assays also in oxygen‐limited conditions. When d ‐xylose was the carbon source, ethanol yields were higher (0.11, 0.34 and 0.33, Table 3) than the ones previously described for B. bruxellensis (Codato et al, 2018). However, the fermentative performance of our strains was significantly lower (ethanol yield and productivity, Table 3) than the observed for S. passalidarum and S. stipitis , yeasts commonly used in second‐generation ethanol production (Veras, Parachin, & Almeida, 2017).…”

“…unlike a previous work with different B. bruxellensis isolates (Codato et al, 2018). In fact, although many yeast species are able to assimilate D-xylose, few are competent to natively ferment this sugar to ethanol (Rodrussamee et al, 2018).…”

“…First, this yeast is able to resist to inhibitors generated during the hydrolysis step (such as furfural and acetic acid), as well as to the fermentation environment itself (weak acids, low pH and high ethanol concentrations), which is valuable to this industry (Bassi, Silva, Reis, & Ceccato‐Antonini, 2013; Blomqvist et al, 2011; Moktaduzzaman et al, 2015; Rozpędowska et al, 2011; Tiukova et al, 2014). Second, some strains of B. bruxellensis are able to natively use d ‐xylose and l ‐arabinose as carbon sources (Codato, Martini, Ceccato‐Antonini, & Bastos, 2018; Crauwels et al, 2015). In this sense, it seems reasonable to point that B. bruxellensis could be employed in the second‐generation ethanol production, as it was previously suggested (de Barros Pita et al, 2019).…”

“…In this sense, it seems reasonable to point that B. bruxellensis could be employed in the second‐generation ethanol production, as it was previously suggested (de Barros Pita et al, 2019). However, too little is known regarding the metabolic capacities of this yeast when in the presence of these pentoses (Codato et al, 2018; Crauwels et al, 2015).…”