Abstract:
Although the strategies used by bacteria to adapt to specific environmental conditions are widely reported, fewer studies have addressed how microbes with a cosmopolitan distribution can survive in diverse ecosystems. Exiguobacterium is a versatile genus whose members are commonly found in various habitats. To better understand the mechanisms underlying the universality of Exiguobacterium, we collected 105 strains from diverse environments and performed large-scale metabolic and adaptive ability tests. We found that most Exiguobacterium members have the capacity to survive under wide ranges of temperature, salinity, and pH. According to phylogenetic and average nucleotide identity analyses, we identified 27 putative species and classified two genetic groups: groups I and II. Comparative genomic analysis revealed that the Exiguobacterium members utilize a variety of complex polysaccharides and proteins to support survival in diverse environments and also employ a number of chaperonins and transporters for this purpose. We observed that the group I species can be found in more diverse terrestrial environments and have a larger genome size than the group II species. Our analyses revealed that the expansion of transporter families drove genomic expansion in group I strains, and we identified 25 transporter families, many of which are involved in the transport of important substrates and resistance to environmental stresses and are enriched in group I strains. This study provides important insights into both the overall general genetic basis for the cosmopolitan distribution of a bacterial genus and the evolutionary and adaptive strategies of Exiguobacterium. IMPORTANCE The wide distribution characteristics of Exiguobacterium make it a valuable model for studying the adaptive strategies of bacteria that can survive in multiple habitats. In this study, we reveal that members of the Exiguobacterium genus have a cosmopolitan distribution and share an extensive adaptability that enables them to survive in various environments. The capacities shared by Exiguobacterium members, such as their diverse means of polysaccharide utilization and environmental-stress resistance, provide an important basis for their cosmopolitan distribution. Furthermore, the selective expansion of transporter families has been a main driving force for genomic evolution in Exiguobacterium. Our findings improve our understanding of the adaptive and evolutionary mechanisms of cosmopolitan bacteria and the vital genomic traits that can facilitate niche adaptation.
摘要:
尽管细菌用来适应特定环境条件的策略被广泛报道,很少有研究探讨具有世界性分布的微生物如何在不同的生态系统中生存。Exiguobacterium是一种多才多艺的属,其成员常见于各种栖息地。为了更好地理解外生细菌普遍性的潜在机制,我们从不同的环境中收集了105株菌株,并进行了大规模的代谢和适应能力测试.我们发现,大多数Exiguobacterium成员有能力在很宽的温度范围内生存,盐度,和pH。根据系统发育和平均核苷酸同一性分析,我们确定了27个推定物种,并对两个遗传组进行了分类:I组和II组。比较基因组分析显示,Exiguobacterium成员利用各种复杂的多糖和蛋白质来支持在不同环境中的生存,并且为此目的还使用了许多伴奏蛋白和转运蛋白。我们观察到,第I组物种可以在更多样化的陆地环境中找到,并且比第II组物种具有更大的基因组大小。我们的分析显示,转运蛋白家族的扩展推动了I组菌株的基因组扩展,我们确定了25个运输家庭,其中许多涉及重要底物的运输和对环境胁迫的抗性,并且在I组菌株中富集。这项研究为细菌属的世界性分布的总体一般遗传基础以及外细菌的进化和适应性策略提供了重要见解。重要特征的广泛分布特征使其成为研究可以在多个栖息地生存的细菌的适应性策略的有价值的模型。在这项研究中,我们发现,Exiguobacterium属的成员具有世界性分布,并具有广泛的适应性,使它们能够在各种环境中生存。Exiguobacterium成员共有的能力,例如它们多样化的多糖利用方式和环境胁迫抗性,为其世界性分布提供了重要依据。此外,转运体家族的选择性扩增一直是外生细菌基因组进化的主要驱动力。我们的发现改善了我们对世界性细菌的适应性和进化机制以及可以促进生态位适应的重要基因组特征的理解。