Bacterial associations with the hydromedusa <i>Nemopsis bachei</i> and scyphomedusa <i>Aurelia aurita</i> from the North Atlantic Ocean

Recent studies suggest that jellyfish influence the community composition of marine microorganisms, but few studies have been conducted contrasting communities among different jellyfish taxa. In this study microbial communities were compared between two cnidarians found in North Atlantic Ocean coastal waters during the spring–summer months. Microbial communities associated with the invasive hydrozoan <i>Nemopsis bachei</i> and the cosmopolitan scyphozoan <i>Aurelia aurita</i> (Cnidaria) were characterized based on the 16S rRNA gene sequence. The bacterial communities associated with the jellyfish were significantly different from the communities in seawater, and <i>N. bachei</i> and <i>A. aurita</i> hosted taxon-specific bacterial groups. Gammaproteobacteria, Bacteroidetes and Alphaproteobacteria dominated bacterial sequences on <i>N. bachei</i>, the dominant orders including Vibrionales, Flavobacteriales, Rhizobiales and Rickettsiales. <i>Vibrio</i> spp. and <i>Photobacterium</i> spp. were abundant in <i>N. bachei</i>, and <i>Tenacibaculum</i> sp. (Bacteroidetes) had a host-specific association with <i>N. bachei</i>. Mycoplasmatales was a prominent, unique, and potentially host-promoted association in <i>A. aurita</i>, and overall Cyanobacteria, Tenericutes and unclassified bacteria dominated the sequences in <i>A. aurita</i>. This is the first description of the microbial community composition in <i>N. bachei</i>, which has been reported as an invasive species in eastern North Atlantic waters. Overall these results suggest that different cnidarians in North Atlantic coastal waters promote growth of distinct microbial communities. Jellyfish could thus differentially influence microbially mediated biogeochemical cycles and food webs in regions where they proliferate.已有研究表明，水母可影响海洋微生物群落组成，但针对不同水母类群间微生物群落的对比研究仍较为匮乏。本研究针对春夏季节北大西洋近岸海域中的两种刺胞动物开展微生物群落对比分析：基于16S核糖体RNA（16S rRNA）基因测序技术，对入侵性水螅虫类<i>Nemopsis bachei</i>（巴奇纽螅）以及广布性钵水母类<i>Aurelia aurita</i>（海月水母，刺胞动物门）的附生微生物群落进行了表征。研究发现，水母附生细菌群落与海水细菌群落存在显著差异，且<i>N. bachei</i>和<i>A. aurita</i>分别携带类群特异性的细菌类群。<i>N. bachei</i>的附生细菌序列以γ-变形菌门（Gammaproteobacteria）、拟杆菌门（Bacteroidetes）和α-变形菌门（Alphaproteobacteria）为主，优势菌目包括弧菌目（Vibrionales）、黄杆菌目（Flavobacteriales）、根瘤菌目（Rhizobiales）和立克次体目（Rickettsiales）；<i>N. bachei</i>体内弧菌属（<i>Vibrio</i>）和发光杆菌属（<i>Photobacterium</i>）物种丰度较高，且拟杆菌门的屈挠杆菌属（<i>Tenacibaculum</i>）物种与<i>N. bachei</i>存在宿主特异性共生关系。<i>A. aurita</i>的附生菌群中，柔膜菌目（Mycoplasmatales）是一类显著且独特的类群，推测为宿主促进形成的共生关联；整体而言，<i>A. aurita</i>的细菌序列以蓝细菌门（Cyanobacteria）、软壁菌门（Tenericutes）以及未分类细菌为主。本研究首次对<i>Nemopsis bachei</i>的微生物群落组成进行了系统表征，该物种此前被报道为东北大西洋海域的入侵物种。综合来看，本研究结果表明，北大西洋近岸海域的不同刺胞动物可促进特异性微生物群落的生长繁殖。因此，在水母大量繁殖的海域，它们可通过差异化作用影响微生物介导的生物地球化学循环与食物网结构。