The community structure of coral associated microorganisms will change greatly in coral bleaching. However, the relationship between specific bacteria groups and Symbiodinium, which is easy to be found in the bleaching process, has been ignored for a long time. In this study, the changes of coral microbial community during a natural bleaching event in the South China Sea were studied by 16S rRNA gene high-throughput sequencing. The microbial community composition of bleached corals was significantly different from that of normal corals (P < 0.001). OTUs belong to Bacillus, Exiguobacterium, Oceanobacillus, Saccharibacteria and Ostreobiaceae was significantly increased in the bleaching corals. The relative abundance of 30.9% OTUS changed significantly during coral bleaching. The relative abundance of potential coral pathogenic groups was not significantly different between normal and bleaching corals. Symbiodinium positively correlated bacterial groups accounted for 6.9% and 4.3% in the normal corals and bleached corals, respectively. The dominated groups of potential Symbiodinium-partner bacteria are Lactococcus and Bacillus. The potential Symbiodinium-partner bacterial groups in bleached corals were significantly lower than that in the normal corals, which further showed their coexistence with Symbiodinium. This study provides insight into the role of potential Symbiodinium-partner bacterial groups in the coral bleaching process and supports the theory of beneficial microorganisms for corals.

珊瑚相关微生物的群落结构将在珊瑚褪色中发生巨大变化。然而，在漂白过程中容易发现的特定细菌群与共生素之间的关系已被长期忽略。在这项研究中，通过16S rRNA基因高通量测序研究了南海自然漂白事件中珊瑚微生物群落的变化。漂白珊瑚的微生物群落组成与正常珊瑚明显不同（P  <0.001）。OTU单板属于芽孢杆菌，微小杆菌属，Oceanobacillus，Saccharibacteria和Ostreobiaceae在漂白的珊瑚中显着增加。在珊瑚漂白过程中，OTUS的30.9％的相对丰度发生了显着变化。正常和漂白珊瑚之间，潜在的珊瑚致病菌群的相对丰度没有显着差异。与共生素呈正相关的细菌群分别占正常珊瑚和漂白珊瑚的6.9％和4.3％。潜在的共生菌伴侣细菌的主要群体是乳球菌和芽孢杆菌。漂白珊瑚中潜在的Symbiodinium-伙伴细菌群显着低于正常珊瑚，这进一步表明了它们与Symbiodinium共存。这项研究提供了对潜在的共生菌伴侣细菌群在珊瑚漂白过程中的作用的了解，并支持了有益于珊瑚的微生物的理论。