Instituto de Biociências, Letras e Ciências Exatas, IBILCE/UNESP, R/ Cristóvão Colombo, 2265. Jd Nazareth, Ibilce-Unesp., São José do Rio Preto, São Paulo, Brazil.
LEAF-Linking Landscape Environment Agriculture and Food, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017, Lisbon, Portugal.
Braz J Microbiol. 2020 Mar;51(1):145-150. doi: 10.1007/s42770-019-00149-4. Epub 2019 Sep 4.
With the strong trend toward sustainable technologies, such as the gradual substitution of fossil fuel consumption, improvement in the utilization of sugars from lignocellulosic biomass appears to be an alternative for bioenergy. However, from a number of C sugars, few are used in fermentative processes for ethanol production. One of the reasons is because wild-type Saccharomyces cerevisiae is unable to efficiently co-utilize hexoses and pentoses via specific transporters for each type of sugar. Thus, a system of pentose uptake that is not modulated by D-glucose is required. Here, we were able to identify the presence of sugar/H symporters for D-xylose and L-arabinose, especially for Pichia guilliermondii, where an uptake of D-glucose via symporter was not detected. The best D-xylose uptake route in P. guilliermondii exhibited a K of 48 mM and V of 0.48 mmol h g at the early stationary phase (24 h). For L-arabinose, the best route of uptake exhibited a K of 109 mM and V of 0.8 mmol h g on log phase (12 h). The highest kinetic uptake was observed when the final pH of the medium was below 7. In general, an alkaline medium limited the expression of symporters. The results obtained in this study will help in the further investigation of these symporters through their overexpression in engineered S. cerevisiae.
随着可持续技术的强劲发展趋势，例如逐渐替代化石燃料的消耗，木质纤维素生物质中糖的利用的改善似乎是生物能源的一种替代方案。然而，在许多 C 糖中，只有少数几种可用于发酵生产乙醇的过程。原因之一是野生型酿酒酵母无法通过每种糖的特定转运蛋白有效地共同利用己糖和戊糖。因此，需要一种不被 D-葡萄糖调节的戊糖摄取系统。在这里，我们能够确定 D-木糖和 L-阿拉伯糖的糖/H 转运蛋白的存在，特别是在毕赤酵母中，没有检测到通过转运蛋白摄取 D-葡萄糖。在早期静止期（24 小时），毕赤酵母中 D-木糖最佳摄取途径的 K 值为 48 mM，V 值为 0.48 mmol h g。对于 L-阿拉伯糖，在对数生长期（12 小时），最佳摄取途径的 K 值为 109 mM，V 值为 0.8 mmol h g。当培养基的最终 pH 值低于 7 时，观察到最高的动力学摄取。一般来说，碱性介质限制了转运蛋白的表达。本研究的结果将有助于通过在工程酿酒酵母中过表达这些转运蛋白来进一步研究这些转运蛋白。
