Response of Aerobic Anoxygenic Phototrophic bacteria to carbon limitation@en

Aerobic Anoxygenic Phototrophic (AAP) bacteria are an important component of freshwater bacterioplankton. They can support their heterotrophic metabolism with energy from light, and by that enhance their growth efficiency. Based on results from cultures, it was hypothesized that photoheterotrophy provides an advantage under carbon limitation and facilitates access to recalcitrant or low-energy carbon sources. However, verification of these hypotheses for natural AAP communities has been lacking. Here, we conducted whole community manipulation experiments and compared the growth of AAP bacteria under carbon limited and with recalcitrant (lignin) or low energy (acetate) carbon sources under dark and infra-red (IR) light conditions to elucidate how they profit from photoheterotrophy. We performed two whole community manipulation experiments in 2-litre microcosms. The first experiment was conducted in June 2018. Lignin was used as the recalcitrant carbon source. Samples were collected every 12 hours. The second experiment was conducted in October 2018. Acetate was used as the low-energy carbon source. Samples were collected every 24 hours. Both experiments were done in at in situ temperature. We measured concentrations of bacteriochlorophyll-a, total prokaryotic count, aerobic anoxygenic phototrophic bacteria count, and heterotrophic nanoflagellates count. This dataset is related to Piwosz et al. (in prep).好氧不产氧光合（Aerobic Anoxygenic Phototrophic, AAP）细菌是淡水浮游细菌群落的重要组成类群。它们可利用光能为异养代谢供能，进而提升自身生长效率。基于纯培养研究结果，已有假说提出光异养代谢在碳受限环境中具备生存优势，并可帮助菌体利用难降解或低能量碳源。然而，针对自然环境中AAP细菌群落的相关假说验证仍存在空白。 本研究开展了全群落操控实验，对比了碳受限条件下，以及分别添加难降解碳源（木质素）或低能量碳源（乙酸盐）时，AAP细菌在黑暗与红外光（infra-red, IR）环境下的生长情况，以阐明其从光异养代谢中获益的具体机制。 我们在2升微型生态系统中开展了两组全群落操控实验：第一组实验于2018年6月进行，以木质素作为难降解碳源，每12小时采集一次样本；第二组实验于2018年10月开展，以乙酸盐作为低能量碳源，每24小时采集一次样本。两组实验均在原位温度条件下完成。 本研究测定了细菌叶绿素a（bacteriochlorophyll-a）浓度、原核生物总计数、好氧不产氧光合细菌计数，以及异养纳米鞭毛虫（heterotrophic nanoflagellates）计数。本数据集关联Piwosz等人（待刊）的研究成果。