Bižić-Ionescu Mina, Zeder Michael, Ionescu Danny, Orlić Sandi, Fuchs Bernhard M, Grossart Hans-Peter, Amann Rudolf
Max Planck Institute for Marine Microbiology, Bremen, 28359, Germany.
Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin, 16775, Germany.
Environ Microbiol. 2015 Oct;17(10):3500-14. doi: 10.1111/1462-2920.12466. Epub 2014 Apr 24.
Marine and limnic particles are hotspots of organic matter mineralization significantly affecting biogeochemical element cycling. Fluorescence in-situ hybridization and pyrosequencing of 16S rRNA genes were combined to investigate bacterial diversity and community composition on limnic and coastal marine particles > 5 and > 10 μm respectively. Limnic particles were more abundant (average: 1 × 10(7) l(-1)), smaller in size (average areas: 471 versus 2050 μm(2)) and more densely colonized (average densities: 7.3 versus 3.6 cells 100 μm(-2)) than marine ones. Limnic particle-associated (PA) bacteria harboured Alphaproteobacteria and Betaproteobacteria, and unlike previously suggested sizeable populations of Gammaproteobacteria, Actinobacteria and Bacteroidetes. Marine particles were colonized by Planctomycetes and Betaproteobacteria additionally to Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria. Large differences in individual particle colonization could be detected. High-throughput sequencing revealed a significant overlap of PA and free-living (FL) bacteria highlighting an underestimated connectivity between both fractions. PA bacteria were in 14/21 cases more diverse than FL bacteria, reflecting a high heterogeneity in the particle microenvironment. We propose that a ratio of Chao 1 indices of PA/FL < 1 indicates the presence of rather homogeneously colonized particles. The identification of different bacterial families enriched on either limnic or marine particles demonstrates that, despite the seemingly similar ecological niches, PA communities of both environments differ substantially.
海洋和淡水颗粒是有机物矿化的热点区域，对生物地球化学元素循环有显著影响。结合荧光原位杂交和16S rRNA基因焦磷酸测序技术，分别研究了大于5μm和大于10μm的淡水和沿海海洋颗粒上的细菌多样性和群落组成。淡水颗粒数量更多（平均：1×10⁷ l⁻¹），尺寸更小（平均面积：471对2050μm²），且比海洋颗粒的定殖密度更高（平均密度：7.3对3.6个细胞100μm⁻²）。与淡水颗粒相关的（PA）细菌含有α-变形菌纲和β-变形菌纲，与之前认为的大量γ-变形菌纲、放线菌纲和拟杆菌纲不同。除了α-变形菌纲、拟杆菌纲和γ-变形菌纲外，海洋颗粒还被浮霉菌门和β-变形菌纲定殖。可以检测到单个颗粒定殖存在很大差异。高通量测序显示PA细菌和自由生活（FL）细菌有显著重叠，突出了这两个部分之间被低估的连通性。在14/21的案例中，PA细菌比FL细菌更多样化，反映了颗粒微环境中的高度异质性。我们提出，PA/FL的Chao 1指数比值<1表明存在定殖相当均匀的颗粒。对在淡水或海洋颗粒上富集的不同细菌家族的鉴定表明，尽管生态位看似相似，但这两种环境中的PA群落有很大差异。
