Antifungal susceptibility of yeasts isolated from anthropogenic watershed

Abstract Yeasts are unicellular fungi widespread in the environment, and studies suggest that there is a positive correlation between yeast and polluted aquatic environments. The aim of this study was to analyze the diversity and resistance of yeasts isolated from water samples collected along the Arroio Dilúvio in Porto Alegre to antifungals. Yeast isolates from the Arroio Dilúvio were subjected to susceptibility assays against antifungals using the minimum inhibitory concentration (MIC) test, and amplification of the ITS1-5.8S-IT2 region; in addition, the ITS-5.8S region was sequenced for some of the isolates. The amplification product was subjected to PCR-RFLP, and the restriction profile allowed the construction of a dendrogram. Susceptibility tests showed a high prevalence of resistance to azole antifungals, where 16.8% of the isolates had a resistance profile to amphotericin B. The sequence analysis allowed the identification of Candida species, including potentially pathogenic species, and species of the Debaryomyces spp. The resistance to antifungals in yeasts isolated from Arroio Dilúvio reinforces the importance of studies of environmental microbiota, and indicates that environmental degradation influences the phenotype displayed.

摘要：酵母菌是广泛分布于环境中的单细胞真菌，已有研究证实，酵母菌与受污染水生环境之间存在正相关关联。本研究旨在分析取自巴西波尔图阿雷格里港（Porto Alegre）阿罗约迪卢维乌河（Arroio Dilúvio）沿岸水样中分离得到的酵母菌的多样性及其对抗真菌剂的耐药性。研究团队对上述分离菌株采用最低抑菌浓度（minimum inhibitory concentration, MIC）试验开展抗真菌剂敏感性检测，并对ITS1-5.8S-IT2区域进行扩增；此外，还对部分菌株的ITS-5.8S区域进行了测序。对扩增产物实施PCR-RFLP（聚合酶链反应-限制性片段长度多态性）分析，并通过限制性酶切图谱构建了聚类树谱。敏感性试验结果显示，酵母菌对唑类抗真菌剂的耐药性检出率较高，且有16.8%的菌株对两性霉素B（amphotericin B）呈现耐药表型。序列分析成功鉴定出假丝酵母属（Candida）菌株，其中涵盖潜在致病菌株以及德巴利酵母属（Debaryomyces spp.）物种。从阿罗约迪卢维乌河分离得到的酵母菌所表现出的抗真菌剂耐药性，进一步强化了环境微生物组研究的重要性，同时表明环境退化会对菌株的表型特征产生影响。