We isolated two Candida pseudointermedia strains from the Atlantic rain forest in Brazil, and analyzed cellobiose metabolization in their cells. After growth in cellobiose medium, both strains had high intracellular β-glucosidase activity [~ 200 U (g cells)−1 for 200 mM cellobiose and ~ 100 U (g cells)−1 for 2 mM pNPβG] and negligible periplasmic cellobiase activity. During batch fermentation, the strain with the best performance consumed all the available cellobiose in the first 18 h of the assay, producing 2.7 g L−1 of ethanol. Kinetics of its cellobiase activity demonstrated a high-affinity hydrolytic system inside cells, with Km of 12.4 mM. Our data suggest that, unlike other fungal species that hydrolyze cellobiose extracellularly, both analyzed strains transport it to the cytoplasm, where it is then hydrolyzed by high-affinity intracellular β-glucosidases. We believe this study increases the fund of knowledge regarding yeasts from Brazilian microbiomes.

中文翻译：

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从腐木中分离的假中间假丝酵母菌株中纤维二糖分解代谢的生化分析

我们从巴西的大西洋雨林中分离了两种假中间假丝酵母菌株，并分析了它们细胞中的纤维二糖代谢。在纤维二糖培养基中生长后，两种菌株都具有高细胞内 β-葡萄糖苷酶活性 [~ 200 U（g 细胞）-1 用于 200 mM 纤维二糖和~ 100 U（g 细胞）-1 用于 2 mM pNPβG]和可忽略不计的周质纤维二糖酶活性。在分批发酵过程中，性能最佳的菌株在试验的前 18 小时内消耗了所有可用的纤维二糖，产生了 2.7 g L-1 的乙醇。其纤维二糖酶活性的动力学表明细胞内具有高亲和力水解系统，Km 为 12.4 mM。我们的数据表明，与在细胞外水解纤维二糖的其他真菌物种不同，两种分析的菌株都将其转运到细胞质中，然后被高亲和力的细胞内β-葡萄糖苷酶水解。我们相信这项研究增加了有关巴西微生物群落酵母的知识储备。