Thomson-Laing Georgia, Puddick Jonathan, Laroche Olivier, Fulton Samantha, Steiner Konstanze, Heath Mark W, Wood Susanna A
Cawthron Institute, Nelson, New Zealand.
Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, HI, United States.
Front Microbiol. 2020 Feb 6;11:129. doi: 10.3389/fmicb.2020.00129. eCollection 2020.
Benthic proliferations of (basionym ) and closely related taxa are being reported with increasing frequency in streams and rivers worldwide. This species commonly produces the potent neurotoxin anatoxin, and exposure to this has resulted in animal fatalities and human health concerns. Bacterial communities within cyanobacterial assemblages can facilitate processes such as nutrient cycling and are posited to influence cyanobacterial growth and function. However, there is limited knowledge on spatial variability of bacterial communities associated with benthic cyanobacteria and anatoxin content and quotas. In this study, -dominated mat samples were collected from six sites in two New Zealand streams. Associated bacterial communities were characterized using 16S rRNA metabarcoding, anatoxin content by liquid chromatography-mass spectrometry and copies using droplet digital PCR. Bacterial assemblages differed significantly when amplicon sequence variants were compared between streams and most sites within streams. These differences were associated with conductivity, DRP, DIN, temperature, anatoxin concentration, and quota. Despite the differences in bacterial community composition; at phyla, class and order levels there was high similarity across spatial scales, with Bacteroidetes (ca. 67%) and Proteobacteria (ca. 25%) dominant. There was significant variability in total anatoxin concentrations between sites in both streams ( < 0.001). When the data were converted to anatoxin quotas variability was reduced, suggesting that the relative abundance of toxic genotypes is a key driver of total anatoxin concentrations in mats. This study demonstrates the complexity of microbial communities within -dominated mats and highlights their likely important role in within-mat nutrient cycling processes.
在全球范围内的溪流和河流中，（基原异名）及其近缘分类群的底栖生物增殖现象的报道频率越来越高。该物种通常会产生强效神经毒素anatoxin，接触这种毒素已导致动物死亡并引发了对人类健康的担忧。蓝藻组合中的细菌群落可以促进诸如养分循环等过程，并被认为会影响蓝藻的生长和功能。然而，关于与底栖蓝藻相关的细菌群落的空间变异性以及anatoxin含量和配额的了解有限。在本研究中，从新西兰两条溪流的六个地点采集了以 为主的席状样本。使用16S rRNA宏条形码对相关细菌群落进行表征，通过液相色谱 - 质谱法测定anatoxin含量，并使用液滴数字PCR测定 拷贝数。当比较不同溪流之间以及溪流内大多数地点的扩增子序列变体时，细菌组合存在显著差异。这些差异与电导率、溶解性活性磷（DRP）、溶解性无机氮（DIN）、温度、anatoxin浓度和配额有关。尽管细菌群落组成存在差异，但在门、纲和目水平上，跨空间尺度具有高度相似性，拟杆菌门（约67%）和变形菌门（约25%）占主导地位。两条溪流中不同地点的总anatoxin浓度存在显著差异（<0.001）。当数据转换为anatoxin配额时，变异性降低，这表明有毒基因型的相对丰度是席状样本中总anatoxin浓度的关键驱动因素。本研究证明了以 为主的席状样本中微生物群落的复杂性，并突出了它们在席状样本内养分循环过程中可能发挥的重要作用。
