Scheffersomyces stipitis is a Crabtree-negative pentose fermenting yeast, which shows a complex respiratory system involving a cytochrome and an alternative salicylhydroxamic acid (SHAM)-sensitive respiration mechanism that is poorly understood. This work aimed to investigate the role of the antimycin A (AA) sensitive respiration and SHAM-sensitive respiration in the metabolism of xylose and glucose by S. stipitis, upon different agitation conditions. Inhibition of the SHAM-sensitive respiration caused a significant (P < 0.05) decrease in glycolytic flux and oxygen consumption when using glucose and xylose under agitation conditions, but without agitation, only a mild reduction was observed. The combination of SHAM and AA abolished respiration, depleting the glycolytic flux using both carbon sources tested, leading to increased ethanol production of 21.05 g/L at 250 rpm for 0.5 M glucose, and 8.3 g/L ethanol using xylose. In contrast, inhibition of only the AA-sensitive respiration, caused increased ethanol production to 30 g/L using 0.5 M glucose at 250 rpm, and 11.3 g/L from 0.5 M xylose without agitation. Results showed that ethanol production can be induced by respiration inhibition, but the active role of SHAM-sensitive respiration should be considered to investigate better conditions to increase and optimize yields.

中文翻译：

---

对树干舍弗氏菌交替呼吸系统的抑制及对葡萄糖或木糖发酵的影响

Scheffersomyces stipitis 是一种 Crabtree 阴性戊糖发酵酵母，它显示出一个复杂的呼吸系统，涉及一种细胞色素和另一种水杨异羟肟酸 (SHAM) 敏感的呼吸机制，但人们对此知之甚少。本工作旨在研究在不同搅拌条件下，抗霉素 A (AA) 敏感呼吸和 SHAM 敏感呼吸在树干链球菌木糖和葡萄糖代谢中的作用。当在搅拌条件下使用葡萄糖和木糖时，SHAM敏感呼吸的抑制导致糖酵解通量和耗氧量显着降低（P＜0.05），但在没有搅拌的情况下，仅观察到轻度降低。SHAM 和 AA 的组合消除了呼吸作用，使用测试的两种碳源消耗了糖酵解通量，导致 0.5 M 葡萄糖在 250 rpm 下乙醇产量增加 21.05 g/L，使用木糖乙醇产量增加 8.3 g/L。相比之下，仅抑制对 AA 敏感的呼吸，导致乙醇产量增加至 30 g/L，使用 0.5 M 葡萄糖在 250 rpm 和 11.3 g/L 从 0.5 M 木糖无需搅拌。结果表明，呼吸抑制可诱导乙醇生产，但应考虑 SHAM 敏感呼吸的积极作用，以寻找更好的条件来提高和优化产量。