Common Actinobacteria and their phages. Ecology of abundant freshwater Actinobacteria

Actinobacteria of the acI lineage ('Ca. Nanopelagicales') are ubiquitously present and often among the most abundant microbes in freshwater lakes around the globe. While several hypotheses for their success have been advanced based on culture-independent approaches, most remain untested owing to a lack of cultivated representatives. It is thus essential to isolate environment acI strains in order to get a holistic picture of their ecology and role in the ecosystem. Moreover, community manipulation experiments suggested that top-down control of acI through viral lysis might be stronger than through grazers. Using acI cultures, we aim to isolate viruses with clearly specified hosts, identify novel acI viruses and determine host ranges. With additional experimental work, these cultures will help us identify the reasons why acI actinobacteria are so abundant even in the presence of viruses.

acI类群的放线菌（‘候选纳米浮游菌目（Ca. Nanopelagicales）’）在全球各类淡水湖泊中广泛存在，且通常是丰度最高的微生物类群之一。尽管基于非培养依赖方法已提出多种解释其生态优势的假说，但由于缺乏可培养的代表菌株，绝大多数假说仍未得到验证。因此，分离环境来源的acI菌株对于全面解析其生态学特征与在生态系统中的功能至关重要。此外，群落操控实验表明，通过病毒裂解对acI类群的下行控制作用可能强于通过捕食者产生的控制作用。借助acI菌株的纯培养物，本研究计划分离获得宿主明确的病毒，鉴定新型acI病毒并确定其宿主范围。结合后续的实验研究，这些纯培养物将助力我们解析即使在病毒存在的情况下，acI放线菌仍能保持极高丰度的原因。