Mei Xiangyuan, Wu Chunhui, Zhao Jin, Yan Tian, Jiang Peng
CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
Front Microbiol. 2019 May 28;10:1192. doi: 10.3389/fmicb.2019.01192. eCollection 2019.
Golden tides dominated by spp. are occurring at an accelerated rate worldwide. In China, has started to bloom in the Yellow Sea and led to tremendous economic losses, but the underlying biological causes and mechanisms are still unclear. Although algae-associated bacteria were suggested to play crucial roles in algal blooms, the profiles of bacteria associated with drifting remain unexplored. In this study, the community structures and functions of -associated bacteria were analyzed using the high-throughput sequencing data of the V5-V7 hypervariable region of the 16S rRNA gene. Molecular identification revealed that the golden tide analyzed in the Yellow Sea was dominated by a single species, . They were a healthy brown color nearshore but were yellow offshore with significantly decreased chlorophyll contents ( < 0.01), which indicates that yellow was under physiological stress. The structural and functional analyses of bacterial communities indicated that the drifting had an obvious selectivity on their associated bacteria against surrounding seawater. Although the bacterial communities phylogenetically differed between brown and yellow ( < 0.01), their dominant functions were all nitrogen and iron transporters, which strongly indicates microbial contribution to blooming of the algal host. For the first time, potential epiphytic and endophytic bacteria associated with were independently analyzed by a modified co-vortex method with silica sand. We showed that the composition of dominant endophytes, mainly and , was relatively consistent regardless of host status, whereas the epiphytic operational taxonomic units (OTUs) greatly varied in response to weakness of host status; however, dominant functions were consistent at elevated intensities, which might protect the host from stress related to nitrogen or iron deficiency. Thus, we propose that host physiological status at different intensities of functional demands, which were related to variable environmental conditions, may be a critical factor that influences the assembly of epiphytic bacterial communities. This study provided new insight into the structure and potential functions of associated bacteria with golden tide blooms.
由 种主导的金潮在全球范围内正以加速的速度出现。在中国， 已开始在黄海大量繁殖并造成了巨大的经济损失，但其潜在的生物学原因和机制仍不清楚。尽管有人认为与藻类相关的细菌在藻华形成中起着关键作用，但与漂浮的 相关的细菌概况仍未得到探索。在本研究中，利用16S rRNA基因V5-V7高变区的高通量测序数据，分析了与 相关细菌的群落结构和功能。分子鉴定表明，在黄海分析的金潮由单一物种 主导。它们在近岸呈健康的棕色，但在近海呈黄色，叶绿素含量显著降低（<0.01），这表明黄色 处于生理应激状态。细菌群落的结构和功能分析表明，漂浮的 对其相关细菌相对于周围海水具有明显的选择性。尽管棕色和黄色 的细菌群落在系统发育上存在差异（<0.01），但它们的主要功能都是氮和铁转运蛋白，这强烈表明微生物对藻类宿主大量繁殖有贡献。首次采用改良的硅砂共涡旋法独立分析了与 相关的潜在附生细菌和内生细菌。我们发现无论宿主状态如何，主要为 和 的优势内生菌组成相对一致，而附生操作分类单元（OTU）因宿主状态的减弱而有很大差异；然而，在强度升高时主要功能是一致的，这可能保护宿主免受与氮或铁缺乏相关的压力。因此，我们提出，与可变环境条件相关的不同功能需求强度下的宿主生理状态，可能是影响附生细菌群落组装的关键因素。本研究为金潮藻华相关细菌的结构和潜在功能提供了新的见解。
