患拟油壶菌病条斑紫菜表面附生菌群分析

Epiphytic Microbial Communities Associated with Neopyropia yezoensis with Olpidiopsis Disease

拟油壶菌病(Oplidiopsis disease)是海上栽培紫菜(Porphyra sensu lato)的主要病害之一,常引起紫菜大面积病烂并造成严重经济损失。本研究利用拟油壶菌感染海区内不同健康状态下的条斑紫菜(Neopyropia yezoensis)[未发生任何病烂(PyOlpH)、部分紫菜发生病烂(PyOlpM)和发生严重病烂(PyOlpS)],分析其附生菌群多样性、群落结构和主要类群之间的相互作用。结果显示,3种紫菜附生菌群α多样性指数不存在显著差异,但PyOlpM组指数高于其他组。3种紫菜附生菌群共有可操作分类单元(operational taxonomic unit,OTU)数仅占总OTU数的22.7%,菌群之间存在显著差异(置换多元方差分析,R^(2)=0.405,P<0.05)。紫菜感染程度越高,与PyOlpH之间的差异类群数量越多。共注释出23门208属,α-变形菌纲(α-Proteobacteria)、γ-变形菌纲(γ-Proteobacteria)和厚壁菌门(Firmicutes)在所有样品中均占优势,相对丰度前20个属中有16个也位于这3个类群中,且随着感染程度的增加分别出现递增或递减的趋势。其中,贪铜菌属(Cupriavidus)和鞘氨醇单胞菌属(Sphingomonas)是共现网络中连接度最高的细菌类群,二者及其依靠正相互作用连接的细菌类群之间存在负相互作用。本研究可为阐明拟油壶菌致病的微生态机制及寻找生防细菌提供一定的数据支持。

Olpidiopsis disease is one of the main diseases affecting laver cultivation in the sea,often causing large-scale rot and serious economic losses.Although the oomycetic genus Olpidiopsis has been identified as the pathogen,little is known regarding its mechanisms,including its interaction with epiphytic microbial communities.In the present study,diversities,structures,and major interactions of epiphytic microbial communities were analyzed using Neopyropia yezoensis in sea infected by Olpidiopsis.The N.yezoensis used in the experiment had different health statuses,including no infection(Py OlpH),partial infection(Py OlpM),and serious infection(PyOlpS).The results showed that no significant difference was observed for theαdiversity indices among microbial communities associated with the three groups of N.yezoensis,but those of PyOlpM were higher than the other two.Shared operational taxonomic units(OTUs)among the three groups of communities only accounted for 22.7%of the total OTUs,in addition to significant community dissimilarity(permutational multivariate analysis of variance,R^(2)=0.405,P<0.05).More microbial taxa were obtained when communities associated with more seriously infected N.yezoensis compared to those associated with PyOlpH.In total,208 genera belonging to 23 phyla were annotated,andα-Proteobacteria,γ-Proteobacteria,and Firmicutes were dominant in all samples.Sixteen of the top 20 genera were also assigned to the three groups,with their relative abundances increasing or decreasing across the infection status from none to severe.Among them,genera Cupriavidus and Sphingomonas were the most connected bacterial taxa in the co-occurrence network,and negative interactions were determined between the two taxa and their positively interacting bacterial taxa.This study provides primary datasets for clarifying the microbial ecological mechanisms and searching for probiotics for Olpidiopsis disease.