Aerobic anoxygenic phototrophic (AAP) bacteria are a phylogenetically diverse and ubiquitous group of prokaryotes that use organic matter but can harvest light using bacteriochlorophyll a. Although the factors regulating AAP ecology have long been investigated through field surveys, the few available experimental studies have considered AAPs as a group, thus disregarding the potential differential responses between taxonomically distinct AAP assemblages. Here, we used sequencing of the pufM gene to describe the diversity of AAPs in 10 environmentally distinct temperate lakes, and to investigate the taxonomic responses of AAP communities in these lakes when subjected to similar experimental manipulations of light and predator removal. The studied communities were clearly dominated by Limnohabitans AAP but presented a clear taxonomic segregation between lakes presumably driven by local conditions, which was maintained after experimental manipulations. Predation reduction (but not light exposure) caused significant compositional shifts across most assemblages, but the magnitude of these changes could not be clearly related to changes in bulk AAP abundances or taxonomic richness of AAP assemblages during experiments. Only a few operational taxonomic units, which differed taxonomically between lakes, were found to respond positively during experimental treatments. Our results highlight that different freshwater AAP communities respond differently to similar control mechanisms, highlighting that in-depth knowledge on AAP diversity is essential to understand the ecology and potential role of these photoheterotrophs.

中文翻译：

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分类学差异决定了淡水需氧生氧光养细菌群落对光照和捕食的响应。

有氧产氧养养性细菌（AAP）是系统发育多样且普遍存在的一组原核生物，它们使用有机物质，但可以使用叶绿素a收集光。尽管调节AAP生态的因素早已通过现场调查进行了研究，但很少有可用的实验研究将AAP视为一个整体，从而无视分类学上不同的AAP组合之间的潜在差异反应。在这里，我们使用pufM基因的测序来描述10个环境温带湖泊中AAP的多样性，并研究这些湖泊在经历类似的光照和捕食者清除实验操作后在AAP群落中的分类学响应。所研究的社区明显受Limnohabitans AAP的支配，但是在湖泊之间存在明显的分类学隔离，这大概是受当地条件驱动的，在实验操作后得以维持。捕食减少（但不是曝光）导致大多数组合物发生明显的成分变化，但是这些变化的幅度与实验期间AAP组合物的总体丰度或分类学丰富度的变化没有明显关系。发现只有几个可操作的生物分类单位在湖泊之间的分类上有所不同，在实验处理过程中反应良​​好。我们的结果表明，不同的淡水AAP群落对类似控制机制的反应不同，