坛紫菜养殖周期中的藻际微生物多样性

Microbial diversity of Pyropia haitanensis phycosphere during cultivation

摘要:

摘要:【目的】坛紫菜是我国江浙海区栽培地主要经济藻类。观察紫菜养殖过程中藻际微生物的群落特点及变化，研究藻际环境中的微生物因素在紫菜栽培中的作用，为保证紫菜健康生长及病害防治提供理论与实验基础。【方法】采用传统纯培方法和PCR-DGGE 技术分离归类坛紫菜养殖周期中的藻际微生物，并利用16SrDNA (细菌)和18S rDNA(真菌)序列测定及在线BLAST比对鉴定到属，比较分析不同生长阶段、不同养殖海区及养殖过程的坛紫菜藻际微生物的多样性特点。【结果】在坛紫菜养殖过程中总共分离到467株细 菌，共41个属。分类结果显示藻际细菌归属于变形菌门(Alphaproteobacteria和Gammaproteobacteria)、放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)，优势菌群为α-变形菌纲和γ-变形菌纲。分离到55株真菌，共15个属。分类结果显示绝大多数真菌归属于子囊菌门(Ascomycota)，仅1株归属于担子菌门(Basidiomycota)伞菌纲(Agaricomycetes)。细菌多样性大于真菌。坛紫菜藻际细菌有19个特异菌属，对照海水细菌有13个特异菌属;从丝状体中分离到大部分真菌和放线菌，坛紫菜养殖丝状体和不同叶状体养殖阶段的藻际微生物类别差异明显。在分离的坛紫菜藻际微生物中发现了与引起细菌性红烂病的海科贝特菌(Cobetia marina)、引起白斑病的紫菜茎点菌(Phoma porphyrae)高度相似的菌株，以及与典型的腐霉如镰孢霉菌(Fusarium sp.)和曲霉(Aspergillus sp.)高度相似的菌株。【结论】坛紫菜养殖过程中藻际微生物的多样性受到紫菜生长形态、养殖时间及养殖环境等因素的影响。在藻际微生物中发现与紫菜致病菌高度相似的微生物，作为潜在致病微生物应得到重视。

Abstract:

Abstract:［Objective］Pyropia haitanensis is of great commercial importance and wildly cultivated in Zhejiang and Fujian provinces． To observe the characteristics and changes of phycosphere microbial communities during cultivation can help us monitor the potential pathogens and microbial factors affecting the health of cultivated seaweeds.［Methods］The morphological characteristics and the diversity of phycosphere and surrounding seawater microbes were studied by pure culture method and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Similarity analysis was carried out online with the 16S rDNA (bacteria) and 18S rDNA (fungi) sequences in GenBank. The phycosphere microbial diversity during different growth stages，cultivated areas and periods was studied.［Results］Totally 467 bacteria and 55 fungi were isolated during P. haitanensis cultivation． The diversity of fungi was smaller than that of bacteria. The bacteria were classified into 41 genera，belonging to Alphaproteobacteria, Gammaproteobacteria，Actinobacteria，Firmicutes and Bacteroidetes. The dominant bacterial communities were Alphaproteobacteria and Gammaproteobacteria． Most of the fungi were classified into Ascomycota，only one strain belonging to the Basidiomycota，Agaricomycetes. Bacteria of 19 specific genera were isolated from P. haitanensis while 13 specific genera were isolated from the surrounding seawater. Most actinomycetes and fungi were isolated from the conchocelis cultured indoors，which was different from the microbial communities of the thalli in intertidal zone. Within the isolated microbes，we found that some strains had very high similarity with those pathogens such as Cobetia marina (C. marina，P. haitanensis red-rotting disease)，Phoma porphyrae (P. yezoensis disease) and saprotrophic fungi Fusarium sp. and Aspergillus sp.［Conclusion］The diversity of Pyropia phycoshpere microbes during cultivation was affected by the seaweed morphology，culture time and environmental factors. The strains that shared high similarity with Pyropia pathogens were found in this study，which would cause our great attention to these potential pathogens for Pyropia diseases.