Laboratory of Biochemistry and Genetics, Federal University of Fronteira Sul, Campus Chapecó, Rodovia SC 484, Km 2, Bairro Fronteira Sul, Chapecó, SC, 89815-899, Brazil.
Department of Microbiology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
Arch Microbiol. 2020 Sep;202(7):1729-1739. doi: 10.1007/s00203-020-01884-1. Epub 2020 Apr 23.
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) for 200 mM cellobiose and ~ 100 U (g cells) 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 of ethanol. Kinetics of its cellobiase activity demonstrated a high-affinity hydrolytic system inside cells, with K 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.
我们从巴西的大西洋雨林中分离出两株假热带念珠菌，并分析了它们细胞内的纤维二糖代谢。在纤维二糖培养基中生长后，两株菌均具有较高的细胞内β-葡萄糖苷酶活性[200 U（g 细胞）用于 200 mM 纤维二糖和100 U（g 细胞）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，表现最好的菌株在测定的前 18 小时内消耗了所有可用的纤维二糖，产生了 2.7 g L 的乙醇。其细胞β-葡萄糖苷酶活性的动力学表明，细胞内存在一种高亲和力的水解系统，其 K 值为 12.4 mM。我们的数据表明，与其他在外切纤维二糖的真菌不同，这两种分析的菌株将其运输到细胞质中，然后在细胞质中被高亲和力的细胞内β-葡萄糖苷酶水解。我们认为这项研究增加了对巴西微生物组中酵母的知识储备。
