Despite the widespread distribution of proteorhodopsin (PR)‐containing bacteria in the oceans, the use of light‐derived energy to promote bacterial growth has only been shown in a few bacterial isolates, and there is a paucity of data describing the metabolic effects of light on environmental photoheterotrophic taxa. Here, we assessed the effects of light on the taxonomic composition, cell integrity and growth responses of microbial communities in monthly incubations between spring and autumn under different environmental conditions. The photoheterotrophs expressing PR in situ were dominated by Pelagibacterales and SAR116 in July and November, while members of Euryarchaeota, Gammaproteobacteria and Bacteroidetes dominated the PR expression in spring. Cell‐membrane integrity decreased under dark conditions throughout most of the assessment, with maximal effects in summer, under low‐nutrient conditions. A positive effect of light on growth was observed in one incubation (out of nine), coinciding with a declining phytoplankton bloom. Light‐enhanced growth was found in Gammaproteobacteria (Alteromonadales) and Bacteroidetes (Polaribacter and Tenacibaculum). Unexpectedly, some Pelagibacterales also exhibited higher growth rates under light conditions. We propose that the energy harvested by PRs helps to maintain cell viability in dominant coastal photoheterotrophic oligotrophs while promoting the growth of some widespread taxa benefiting from the decline of phytoplankton blooms.

中文翻译：

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光支持分类学多样的沿海光异养生物的细胞完整性和生长速率。

尽管海洋中含有含有细菌视紫红质（PR）的细菌广泛分布，但仅在少数细菌分离株中显示了利用光能促进细菌生长的信息，并且缺乏描述光代谢作用的数据。关于环境光异养类群。在这里，我们评估了在不同环境条件下春季和秋季之间每月孵化中光对微生物群落的分类学组成，细胞完整性和生长响应的影响。原位表达PR的光异养菌在7月和11月被Pelagibacterales和SAR116占据主导地位，而Euryarchaeota，Gammaproteobacteria和Bacteroidetes则处于其中。春季主导了PR表达。在大多数评估中，黑暗条件下的细胞膜完整性下降，夏季低营养条件下的影响最大。在一个孵化中（九个孵化中）观察到光对生长有积极影响，这与浮游植物的开花减少有关。光增强的生长是在发现γ-变形菌（Alteromonadales）和拟杆菌（Polaribacter和黏着）。出乎意料的是，一些细菌在光照条件下也表现出较高的增长率。我们认为，PRs收集的能量有助于在主要的沿海光异养寡营养生物中维持细胞活力，同时促进受益于浮游植物开花减少的一些广泛的类群的生长。