Phytoplankton growth and degradation are associated with bacterial communities in phycosphere. We compared the bacterial communities in two algal blooms (Microcystis aeruginosa and Euglena sanguinea). In particular, large particle-associated, small particle-associated, and free-living bacteria were collected in succession using membranes with three different pore sizes (10 µm, 1 µm, and 0.22 µm) in this study. The results showed that Proteobacteria and Bacteroidetes were the dominant phyla in both blooms. Significant differences in the structure, function, and assembly were observed between large particle-associated and free-living bacterial community in both blooms. Specifically, relative abundance of Roseomonas was higher in the large-size (> 10 µm) aggregates, while Candidate_division_TM7 and Candidate_division_SR1 were more abundant in the free-living bacterial community (0.22–1 µm). The large particle-associated bacterial community was mainly driven by heterogeneous selection and dispersal limitation, whereas the small particle-associated and free-living bacterial communities were mostly determined by dispersal limitation. Besides, some specific bacterial subgroups were found between M. aeruginosa and E. sanguinea blooms. Chlorobi, Chloroflexi, and Fusobacteria were abundant in the M. aeruginosa blooms, whereas Deinococcus–Thermus was abundant in the E. sanguinea blooms. Those specific bacteria provide competitive advantages for the dominated algae. Altogether, these findings indicate that the phycosphere of bloom-forming algae provides different ecological niches where different functional bacterial groups can adapt.

中文翻译：

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藻圈内大小分级的聚集体定义了与铜绿微囊藻和裸藻Euglena花朵有关的功能细菌群落

浮游植物的生长和降解与藻圈中的细菌群落有关。我们比较了两个藻华（铜绿微囊藻和裸藻）中的细菌群落。尤其是，在这项研究中，使用具有三种不同孔径（10 µm，1 µm和0.22 µm）的膜连续收集了大颗粒相关，小颗粒相关和自由活动的细菌。结果表明，在两种花中，Proteobacteria和Bacteroidetes是主要的门。在两次开花中，在大颗粒相关和自由生活的细菌群落之间观察到结构，功能和组装的显着差异。具体而言，玫瑰单胞菌的相对丰度在大型（> 10 µm）聚集体中较高，而Candidate_division_TM7和Candidate_division_SR1在自由生活细菌群落中更丰富（0.22–1 µm）。与大颗粒相关的细菌群落主要由异质选择和扩散限制驱动，而与小颗粒相关和自由生活的细菌群落主要由分散限制决定。此外，在M之间发现了一些特定的细菌亚群。铜绿假单胞菌和Ë。几内亚绽放。Chlorobi，绿弯菌门，和Fusobacteria是在丰富的中号。铜绿花盛开，而Deinococcus-Thermus在E中丰富。几内亚绽放。这些特定的细菌为优势藻类提供了竞争优势。总而言之，这些发现表明，形成水华的藻类的藻圈提供了不同的生态位，不同的功能细菌群可以适应这些生态位。