Brandes Josephin, Kuhajek Jeanne M, Goodwin Eric, Wood Susanna A
Cawthron Institute, Private Bag 2, Nelson, 7001, New Zealand.
Department of Biology, University of Konstanz, 78457, Konstanz, Germany.
Microb Ecol. 2016 Oct;72(3):514-25. doi: 10.1007/s00248-016-0816-7. Epub 2016 Jul 13.
Didymosphenia geminata (Lyngbye) M. Schmidt is a stalked freshwater diatom that is expanding its range globally. In some rivers, D. geminata forms thick and expansive polysaccharide-dominated mats. Like other stalked diatoms, D. geminata cells attach to the substratum with a pad of adhesive extracellular polymeric substance. Research on D. geminata and other diatoms suggests that bacterial biofilm composition may contribute to successful attachment. The aim of this study was to investigate the composition and role of bacterial biofilm communities in D. geminata attachment and survival. Bacterial biofilms were collected at four sites in the main stem of a river (containing D. geminata) and in four tributaries (free of D. geminata). Samples were characterised using automated rRNA intergenic spacer analysis and high-throughput sequencing (HTS). Mat-associated bacteria were isolated and their effect on the early establishment of D. geminata cells assessed using co-culturing experiments. ARISA and HTS data showed differences in bacterial communities between samples with and without D. geminata at two of the four sites. Samples with D. geminata had a higher relative abundance of Sphingobacteria (p < 0.01) and variability in community composition was reduced. Analysis of the 76 bacteria isolated from the mat revealed 12 different strains representing 8 genera. Co-culturing of a Carnobacterium sp. with D. geminata reduced survival (p < 0.001) and attachment (p < 0.001) of D. geminata. Attachment was enhanced by Micrococcus sp. and Pseudomonas sp. (p < 0.001 and p < 0.01, respectively). These data provide evidence that bacteria play a role in the initial attachment and on-going survival of D. geminata, and may partly explain observed distribution patterns.
双眉藻（Didymosphenia geminata (Lyngbye) M. Schmidt）是一种具柄的淡水硅藻，其分布范围正在全球扩大。在一些河流中，双眉藻形成了厚厚的、以多糖为主的藻席。与其他具柄硅藻一样，双眉藻细胞通过一层粘性胞外聚合物垫附着在基质上。对双眉藻和其他硅藻的研究表明，细菌生物膜组成可能有助于成功附着。本研究的目的是调查细菌生物膜群落的组成及其在双眉藻附着和生存中的作用。在一条河流的干流（含有双眉藻）的四个地点和四条支流（不含双眉藻）采集了细菌生物膜样本。使用自动rRNA基因间隔区分析和高通量测序（HTS）对样本进行了表征。分离出与藻席相关的细菌，并通过共培养实验评估它们对双眉藻细胞早期定殖的影响。ARISA和HTS数据显示，在四个地点中的两个地点，有双眉藻和没有双眉藻的样本之间细菌群落存在差异。有双眉藻的样本中鞘脂杆菌的相对丰度更高（p < 0.01），群落组成的变异性降低。对从藻席中分离出的76种细菌的分析揭示了代表8个属的12种不同菌株。一种肉食杆菌属（Carnobacterium sp.）与双眉藻共培养会降低双眉藻的存活率（p < 0.001）和附着率（p < 0.001）。微球菌属（Micrococcus sp.）和假单胞菌属（Pseudomonas sp.）可增强附着（分别为p < 0.001和p < 0.01）。这些数据证明细菌在双眉藻的初始附着和持续生存中发挥作用，并可能部分解释观察到的分布模式。
