State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen 361102, People's Republic of China.
College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, People's Republic of China.
FEMS Microbiol Ecol. 2019 Mar 1;95(3). doi: 10.1093/femsec/fiz017.
Interactions between photoautotrophs and heterotrophs are central to marine microbial ecosystems. Synechococcus are dominant marine phototrophs, and they are frequently associated with heterotrophic bacteria. These co-cultures provide a useful research system to investigate photoautotroph-heterotroph interactions in marine systems. Bacteria within the Roseobacter clade and Flavobacteria are two of the main bacterial lineages that exhibit intimate associations with Synechococcus populations. We conducted metagenomic analyses of a Synechococcus culture, followed by genomic binning of metagenomic contigs, and recovered five nearly complete genomes, including members of the Roseobacter clade (i.e. Marivita sp. XM-24) and Flavobacteria (i.e. Fluviicola sp. XM-24). Marivita sp. XM-24 is an ecological generalist of the Roseobacter clade and displays diverse metabolic capacities for the acquisition of nutrients and energy sources. Specifically, the genome contained numerous gene complements involved in the uptake and metabolism of nitrogen- and phosphorus-containing inorganic and organic compounds, in addition to the potential for aerobic anoxygenic photosynthesis, oxidation of carbon monoxide, inorganic sulfur oxidation, DMSP demethylation and PHA metabolism. The genome of the Flavobacteria representative, Fluviicola sp. XM-24, contained numerous peptidases, glycoside hydrolases, adhesion-related proteins and genes involved in gliding motility. Fluviicola sp. XM-24 likely specialize in the degradation of high molecular weight compound exudates from Synechococcus cells, including polysaccharides and polypeptides via attachment to particles, surfaces or cells. The distinct metabolic strategies identified within several heterotrophic bacteria that are associated with Syneochococcus cells provide insights into their lifestyles and nutrient utilization patterns, in addition to their interactions with photoautotrophs. Biological interactions, including mutualism, competition and antagonism, shape the microbial community structure of marine environments and are critical for understanding biogeochemical cycling in the ocean. These results provide valuable insights into the nature of interactions between dominant marine photoautotrophs and associated bacterial heterotrophs.
光养生物和异养生物之间的相互作用是海洋微生物生态系统的核心。聚球藻是优势海洋光养生物，它们经常与异养细菌相关联。这些共培养物为研究海洋系统中光养生物-异养生物相互作用提供了一个有用的研究系统。罗斯贝氏菌群和黄杆菌群中的细菌是与聚球藻种群密切相关的两个主要细菌谱系。我们对聚球藻培养物进行了宏基因组分析，然后对宏基因组连续体进行基因组分箱，回收了 5 个几乎完整的基因组，包括罗斯贝氏菌群（即 Marivita sp. XM-24）和黄杆菌群（即 Fluviicola sp. XM-24）的成员。Marivita sp. XM-24 是罗斯贝氏菌群的生态通才，具有多样化的代谢能力，可获取营养物质和能源。具体而言，该基因组包含许多与氮和磷含量无机和有机化合物的摄取和代谢有关的基因，以及有氧缺氧光合作用、一氧化碳氧化、无机硫氧化、DMSP 去甲基化和 PHA 代谢的潜力。黄杆菌群代表 Fluviicola sp. XM-24 的基因组包含许多肽酶、糖苷水解酶、粘附相关蛋白和参与滑行运动的基因。Fluviicola sp. XM-24 可能专门通过附着在颗粒、表面或细胞上，降解来自聚球藻细胞的高分子化合物分泌物，包括多糖和多肽。与聚球藻细胞相关的几种异养细菌中确定的独特代谢策略提供了对其生活方式和营养利用模式的深入了解，以及它们与光养生物的相互作用。生物相互作用，包括共生、竞争和拮抗，塑造了海洋环境的微生物群落结构，对理解海洋中的生物地球化学循环至关重要。这些结果为了解优势海洋光养生物和相关细菌异养生物之间的相互作用性质提供了有价值的见解。
