海带孢子体、配子体时期附生菌群落结构的比较

Comparative study on the community structure of epiphytic bacteria in sporophyte and gametophyte stages of kelp Saccharina japonica

中文关键词: 海带  附生菌  16S rRNA  褐藻酸降解菌  蓝细菌门

英文关键词: Saccharina japonica  Epiphytic bacteria  16S rRNA  Alginic acid degrading bacteria  Cyanobacteria

中文摘要:

      为探究海带(Saccharina japonica)生活史孢子体、配子体不同阶段的附生菌群落结构的差异，采用Illumina测序技术，分析了种海带(S1)、配子体(S2)、幼孢子体(S3)和大孢子体(S4)这4个不同阶段的藻体上附生菌16S rRNA序列，研究其附生菌群落结构。结果显示，4个阶段共识别出23门156属共244个操作分类单元(OTU)。从门分类上来说，变形菌门(Proteobacteria)在海带各阶段中均表现出较高的丰度，在S1、S2、S3和S4藻体样本中相对丰度分别达53.0%、94.3%、77.2%和36.7%，蓝细菌门(Cyanobacteria)只在S4藻体样本中表现出较高的丰度，为43.8%；从属分类上来说，假交替单胞菌属(Pseudoalteromonas)在各样本间差异较大，S2、S3和S4样本中相对丰度分别为65.00%、44.88%和25.57%，但在S1样本中仅为0.18%。各样品间附生菌群落结构差异较大，S1与S4样本相邻聚为一支，S2与S3样本为另一支。S2样本的菌群种类单一且分布不均匀，S1、S3与S4样本细菌种类丰富，但S4样本中菌群间的丰度差异较大。海带的苗种繁育阶段(S2和S3)存在褐藻酸降解菌丰度增加的趋势，孢子体阶段(S4)则具有高丰度的共生型蓝细菌。

英文摘要:

      To explore the community structure of epiphytic bacteria on the sporophytes and gametophytes of kelp Saccharina japonica, sequences of 16S rRNA of epiphytic bacteria found on the mature leafy sporophytes (S1), filamentous gametophytes (S2), sporelings (S3), and big leafy sporophytes (S4) were analyzed using Illumina sequencing technology. The results showed that 23 phyla, 156 genera, and 244 kinds of OTUs (Operational Taxonomic Units) were identified in these samples. At the phylum level, Proteobacteria showed higher abundance, with relative abundances of 53.0%, 94.3%, 77.2%, and 36.7% in S1, S2, S3, and S4 samples, respectively. Cyanobacteria showed higher abundance of 43.8% in S4 samples only. At the genus level, the relative abundances of Pseudoalteromonas in S2, S3, and S4 were 65.00%, 44.88%, and 25.57%, respectively, but only 0.18% in S1. The community structure of epiphytic bacteria varied greatly among samples. S1 and S4 samples were clustered together, but S2 and S3 samples were clustered in another branch. The species of the bacteria in S2 samples were single and unevenly distributed. S1, S3, and S4 samples were rich in bacteria, while the relative abundance between different bacteria in S4 samples varied greatly compared to that in other samples. This study revealed that there was an increasing trend in the abundance of alginic acid-degrading bacteria during the breeding stage of S. japonica (S2, and S3), and there was a high abundance of symbiotic Cyanobacteria in the big leafy sporophyte stage (S4).