Dos Reis Jefferson Brendon Almeida, Rodrigues Mayara Oliveira Sousa, Furtado Leila Lourenço, de Sousa Queiroz Júnior Clemildo, do Vale Helson Mario Martins
University of Brasilia (UnB), Institute of Biological Sciences, Department of Phytopathology, Brasília, DF, 70910-900, Brazil.
Folia Microbiol (Praha). 2024 Oct 23. doi: 10.1007/s12223-024-01211-x.
Yeasts are unicellular fungi that occur in a wide range of ecological niches, where they perform numerous functions. Furthermore, these microorganisms are used in industrial processes, food production, and bioremediation. Understanding the physiological and adaptive characteristics of yeasts is of great importance from ecological, biotechnological, and industrial perspectives. In this context, we evaluated the abilities to assimilate and ferment different carbon sources, to produce extracellular hydrolytic enzymes, and to tolerate salt stress, heavy metal stress, and UV-C radiation of two isolates of Eremothecium coryli, isolated from Momordica indica fruits. The two isolates were molecularly identified based on sequencing of the 18S-ITS1-5.8S-ITS2 region. Our isolates were able to assimilate nine carbon sources (dextrose, galactose, mannose, cellobiose, lactose, maltose, sucrose, melezitose, and pectin) and ferment three (glucose, maltose, and sucrose). The highest values of cellular dry weight were observed in the sugars maltose, sucrose, and melezitose. We observed the presence of hyphae and pseudohyphae in all assimilated carbon sources. The two isolates were also capable of producing amylase, catalase, pectinase, and proteases, with the highest values of enzymatic activity found in amylase. Furthermore, the two isolates were able to grow in media supplemented with copper, iron, manganese, nickel, and zinc and to tolerate saline stress in media supplemented with 5% NaCl. However, we observed a decrease in CFU at higher concentrations of these metals and NaCl. We also observed morphological changes in the presence of metals, which include changes in cell shape and cellular dimorphisms. The isolates were sensitive to UV-C radiation in the shortest exposure time (1 min). Our findings reinforce the importance of endophytic yeasts for biotechnological and industrial applications and also help to understand how these microorganisms respond to environmental variations caused by human activities.
酵母是单细胞真菌，广泛存在于各种生态位中，并在其中发挥着多种功能。此外，这些微生物还应用于工业生产、食品制造和生物修复领域。从生态学、生物技术和工业角度来看，了解酵母的生理和适应特性非常重要。在此背景下，我们评估了从木鳖子果实中分离得到的两株榛座壳酵母在同化和发酵不同碳源、产生细胞外水解酶以及耐受盐胁迫、重金属胁迫和UV-C辐射方面的能力。基于18S-ITS1-5.8S-ITS2区域的测序对这两株分离株进行了分子鉴定。我们的分离株能够同化九种碳源（葡萄糖、半乳糖、甘露糖、纤维二糖、乳糖、麦芽糖、蔗糖、松三糖和果胶）并发酵三种（葡萄糖、麦芽糖和蔗糖）。在麦芽糖、蔗糖和松三糖中观察到细胞干重的最高值。我们在所有同化的碳源中都观察到了菌丝和假菌丝的存在。这两株分离株还能够产生淀粉酶、过氧化氢酶、果胶酶和蛋白酶，其中淀粉酶的酶活性最高。此外，这两株分离株能够在添加了铜、铁、锰、镍和锌的培养基中生长，并在添加了5% NaCl的培养基中耐受盐胁迫。然而，我们观察到在这些金属和NaCl浓度较高时，菌落形成单位（CFU）有所下降。我们还观察到在金属存在下的形态变化，包括细胞形状的改变和细胞二态性。分离株在最短暴露时间（1分钟）时对UV-C辐射敏感。我们的研究结果强化了内生酵母在生物技术和工业应用中的重要性，也有助于了解这些微生物如何应对人类活动引起的环境变化。
