Numerous agents of infections in humans and other mammals are found among fungi that are able to survive extreme environmental conditions and to quickly adapt to novel habitats. Nevertheless, the relationship between opportunistic potential and polyextremotolerance was not yet studied systematically in fungi. Here, the link between polyextremotolerance and opportunistic pathogenicity is shown in a kingdom-wide phylogenetic analysis as a statistically significant co-occurrence of extremotolerance (e.g. osmotolerance and psychrotolerance) and opportunism at the level of fungal orders. In addition to extremotolerance, fungal opportunists share another characteristic—an apparent lack of specialised virulence traits. This is illustrated by a comparative genomic analysis of 20 dothideomycetous and eurotiomycetous black fungi. While the genomes of specialised fungal plant pathogens were significantly enriched in known virulence-associated genes that encode secreted proteases, carbohydrate active enzyme families, polyketide synthases, and non-ribosomal peptide synthetases, no such signatures were observed in human opportunists. Together the presented results have several implications. If infection of human hosts is a side effect of fungal stress tolerance and adaptability, the human body is most likely neither the preferred habitat of such species, nor important for their evolutionary success. This defines opportunism as opposed to pathogenicity, where infection is advantageous for the species’ fitness. Since opportunists are generally incapable of the host-to-host transmission, any host-specific adaptations are likely to be lost with the resolution of the infection, explaining the observed lack of specialised virulence traits. In this scenario opportunistic infections should be seen as an evolutionary dead end and unlikely to lead to true pathogenicity.

中文翻译：

---

极端耐受性与人的机会致病性之间的真菌

在真菌中发现了许多人类和其他哺乳动物的感染因子，它们能够在极端的环境条件下生存并迅速适应新的栖息地。然而，真菌中机会潜能与多态性耐受之间的关系尚未得到系统的研究。在这里，在王国范围的系统发育分析中，多态性耐受性和机会致病性之间的联系被显示为在真菌有序水平上，极度耐受性（例如渗透性和心理耐受性）和机会性在统计学上显着共存。除极端耐受外，真菌机会主义者还具有另一个特征-明显缺乏专门的毒力特征。这是通过对20种十二指肠菌种和欧洲菌种黑菌进行的比较基因组分析来说明的。尽管专门的真菌植物病原体的基因组明显富含已知的与毒力相关的基因，这些基因编码分泌的蛋白酶，碳水化合物活性酶家族，聚酮化合物合酶和非核糖体肽合成酶，但在人类机会主义者中未观察到此类特征。一起提出的结果有几个含义。如果人类宿主的感染是真菌胁迫耐受性和适应性的副作用，那么人体很可能既不是此类物种的首选栖息地，也不是它们进化成功的重要因素。与致病性相反，这定义了机会主义，在这种情况下，感染对物种的适应性有利。由于机会主义者通常无法进行宿主之间的传播，因此随着感染的解决，任何针对宿主的适应措施都可能会丢失，解释观察到的缺乏专门的毒力特征。在这种情况下，机会性感染应被视为进化的死角，不太可能导致真正的致病性。