Data_Sheet_1_RNA-Seq Reveals that Light and Darkness Are Different Stimuli in Freshwater Heterotrophic Actinobacteria.PDF

Light is a ubiquitous source of both energy and information in surface environments, and regulates gene expression not only in photosynthetic microorganisms, but in a broad range of photoheterotrophic and heterotrophic microbes as well. Actinobacteria are keystone species in surface freshwater environments, where the ability to sense light could allow them to coordinate periods of nutrient uptake and metabolic activity with primary production. The model freshwater Actinobacteria Rhodoluna (R.) lacicola strain MWH-Ta8 and Aurantimicrobium (A.) photophilum strain MWH-Mo1 grow faster in the light than in the dark, but do not use light energy to support growth. Here, we characterize transcription throughout a light-dark cycle in R. lacicola and A. photophilum. In both species, some genes encoding carbohydrate metabolism and storage are upregulated in the light. However, expression of genes of the TCA cycle is only coordinated with light availability in R. lacicola. In fact, the majority of genes that respond to light and darkness in these two species are different, even though their light-responsive phenotypes are similar. The ability to respond to light and darkness may be widespread in freshwater Actinobacteria, but the genetic networks controlled by these two stimuli may vary significantly.

光是地表环境中无处不在的能量与信息来源，不仅调控光合微生物的基因表达，亦对广泛的光能异养型与异养型微生物产生调控作用。放线菌（Actinobacteria）是地表淡水环境中的关键类群，具备感光能力可使其将营养摄取与代谢活动的周期与初级生产过程相协调。模式淡水放线菌菌株Rhodoluna lacicola MWH-Ta8（以下简称R. lacicola）与Aurantimicrobium photophilum MWH-Mo1（以下简称A. photophilum）在光照条件下的生长速率均高于黑暗环境，但无法利用光能支持生长。本研究对二者在明暗周期下的全转录组特征进行了分析。两个物种中，部分编码碳水化合物代谢与储存相关蛋白的基因在光照条件下均出现表达上调。但三羧酸循环（TCA cycle）相关基因的表达仅在R. lacicola中与光照可获得性呈现协同调控关系。尽管二者的光响应表型相似，但绝大多数响应明暗环境的基因在两个物种中存在显著差异。淡水放线菌中普遍具备响应明暗环境的能力，但两类刺激所调控的遗传网络可能存在显著差异。