PDF(Pubmed)
Abstract：
Sulfur-oxidizing bacteria (SOB) have developed distinct ecological strategies to obtain reduced sulfur compounds for growth. These range from specialists that can only use a limited range of reduced sulfur compounds to generalists that can use many different forms as electron donors. Forming intimate symbioses with animal hosts is another highly successful ecological strategy for SOB, as animals, through their behavior and physiology, can enable access to sulfur compounds. Symbioses have evolved multiple times in a range of animal hosts and from several lineages of SOB. They have successfully colonized a wide range of habitats, from seagrass beds to hydrothermal vents, with varying availability of symbiont energy sources. Our extensive analyses of sulfur transformation pathways in 234 genomes of symbiotic and free-living SOB revealed widespread conservation in metabolic pathways for sulfur oxidation in symbionts from different host species and environments, raising the question of how they have adapted to such a wide range of distinct habitats. We discovered a gene family expansion of soxY in these genomes, with up to five distinct copies per genome. Symbionts harboring only the \"canonical\" soxY were typically ecological \"specialists\" that are associated with specific host subfamilies or environments (e.g., hydrothermal vents, mangroves). Conversely, symbionts with multiple divergent soxY genes formed versatile associations across diverse hosts in various marine environments. We hypothesize that expansion and diversification of the soxY gene family could be one genomic mechanism supporting the metabolic flexibility of symbiotic SOB enabling them and their hosts to thrive in a range of different and dynamic environments.IMPORTANCESulfur metabolism is thought to be one of the most ancient mechanisms for energy generation in microorganisms. A diverse range of microorganisms today rely on sulfur oxidation for their metabolism. They can be free-living, or they can live in symbiosis with animal hosts, where they power entire ecosystems in the absence of light, such as in the deep sea. In the millions of years since they evolved, sulfur-oxidizing bacteria have adopted several highly successful strategies; some are ecological \"specialists,\" and some are \"generalists,\" but which genetic features underpin these ecological strategies are not well understood. We discovered a gene family that has become expanded in those species that also seem to be \"generalists,\" revealing that duplication, repurposing, and reshuffling existing genes can be a powerful mechanism driving ecological lifestyle shifts.
摘要：
硫氧化细菌（SOB）已开发出独特的生态策略，以获得减少的硫化合物用于生长。这些范围从只能使用有限范围的还原硫化合物的专家到可以使用许多不同形式作为电子供体的通才。与动物宿主形成亲密共生是SOB另一个非常成功的生态策略，作为动物,通过他们的行为和生理，可以获得硫化合物。共生体在一系列动物宿主中以及从SOB的几个谱系中进化了多次。他们成功地在各种栖息地定居，从海草床到热液喷口，共生体能源的可用性各不相同。我们对234个共生和自由生活SOB基因组中硫转化途径的广泛分析揭示了来自不同宿主物种和环境的共生体中硫氧化的代谢途径的广泛保守性。提出了他们如何适应如此广泛的不同栖息地的问题。我们在这些基因组中发现了SoxY的基因家族扩展，每个基因组有多达五个不同的拷贝。仅包含“规范”soxY的共生体通常是与特定宿主亚科或环境相关的生态“专家”(例如，热液喷口,红树林）。相反，具有多个不同soxY基因的共生体在各种海洋环境中的不同宿主之间形成了多种关联。我们假设soxY基因家族的扩展和多样化可能是一种支持共生SOB代谢灵活性的基因组机制，使它们及其宿主能够在一系列不同和动态的环境中茁壮成长。重要硫代谢被认为是微生物中最古老的能量产生机制之一。如今，各种微生物的代谢依赖于硫氧化。他们可以自由生活，或者它们可以与动物宿主共生，它们在没有光的情况下为整个生态系统供电，比如在深海中。在它们进化的数百万年里，硫氧化细菌采用了几种非常成功的策略；有些是生态专家，“有些是”通才，“但是这些生态策略的哪些遗传特征还没有得到很好的理解。我们发现了一个基因家族，它在那些似乎也是通才的物种中得到了扩展，“揭示了这种重复，重新利用，重新洗牌现有基因可能是推动生态生活方式转变的强大机制。
