Abstract

Metabolic flexibility controls microbial survival and shapes ecological structures. Although the utilization of a variety of substrates has been studied for individual metabolically versatile microorganisms, only little is known about the response of microbial communities toward substrate fluctuation. Here, we exposed a phototrophic co-culture (Rhodopseudomonas sp. and Chlorobium sp.) that was isolated from a littoral freshwater sediment to a variety of substrates (acetate, Fe(II), or H₂) and followed the abundance of individual microbial partners based on their characteristic light absorption pattern. Chlorobium sp. dominated the culture when Fe(II) was supplied, whereas Rhodopseudomonas sp. decreased below detection. Rhodopseudomonas sp. dominated when the co-culture was transferred onto acetate (Chlorobium sp. below detection). When grown on H₂, the dominance pattern depended on pre-culture conditions. Pre-cultures on Fe(II) or acetate resulted in dominance of Chlorobium sp. or Rhodopseudomonas sp., respectively. Although the relative abundance of the two partner strains strictly relies on substrate availability, we were incapable of isolating Chlorobium sp. from the co-culture. Our study shows how substrate fluctuations shape microbial distribution and points toward potential community interactions that enable microbial survival.

抽象的

代谢的灵活性控制微生物的生存并塑造生态结构。尽管已经针对各种代谢用途广泛的微生物研究了多种底物的利用，但对微生物群落对底物波动的反应知之甚少。在这里，我们将从沿海淡水沉积物中分离出来的光养共培养物（Rhodopseudomonas sp。和Chlorobium sp。）暴露于多种底物（乙酸盐，Fe（II）或H ₂），然后观察单个微生物的丰度伙伴根据其特征性的光吸收模式。绿球藻 当提供Fe（II）时，文化占据主导地位，而杜鹃假单胞菌sp。降低到检测以下。红假单胞菌属。当将共培养物转移到乙酸盐上时（占检测下的Chlorobium sp。）占主导地位。当在H ₂上生长时，优势模式取决于预培养条件。在Fe（II）或醋酸盐上进行预培养后，导致Chlorobium sp。占主导地位。或Rhodopseudomonas sp.。尽管这两个伙伴菌株的相对丰度严格取决于底物的可用性，但我们无法分离出Chlorobium sp。来自共同文化。我们的研究表明底物波动如何影响微生物分布并指出潜在的社区相互作用，从而使微生物得以生存。