Group of Limnology-Department of Continental Ecology. Centre d'Estudis Avançats de Blanes-CSIC, Accés Cala Sant Francesc 14, Blanes, Catalonia, Spain.
Environ Microbiol. 2012 Jun;14(6):1390-402. doi: 10.1111/j.1462-2920.2012.02720.x. Epub 2012 Mar 6.
The ecological significance of the marine bacterial populations distinguishable by flow cytometry on the basis of the fluorescence (FL) of their nucleic acid (NA) content and proxies of cell size (such as side scatter, SSC) remains largely unknown. Some studies have suggested that cells with high NA (HNA) content and high SSC (HS) represent the active members of the community, while the low NA (LNA) cells are inactive members of the same phylogenetic groups. But group-specific activity measurements and phylogenetic assignment after cell sorting have suggested this is not be the case, particularly in open-ocean communities. To test the extent to which the different NA subgroups are similar, and consequently the extent to which they likely have similar ecological and biogeochemical roles in the environment, we analysed the phylogenetic composition of three populations after cell sorting [high NA-high SC (HNA-HS), high NA-low SC (HNA-LS), low NA (LNA)] by 454 pyrosequencing in two contrasting periods of the year in NW Mediterranean coastal waters (BBMO, Blanes Bay Microbial Observatory) where these three populations have recurrent seasonal patterns. Statistical analyses showed that summer and winter samples were significantly different and, importantly, the sorted populations within a sample were composed of different taxa. The majority of taxa were associated with one NA fraction only, and the degree of overlap (i.e. OTUs present simultaneously in 2 fractions) between HNA and LNA and between summer and winter communities was very small. Rhodobacterales, SAR116 and Bacteroidetes contributed primarily to the HNA fraction, whereas other groups such as SAR11 and SAR86 contributed largely to the LNA fractions. Gammaproteobacteria other than SAR86 showed less preference for one particular NA fraction. An increase in diversity was observed from the LNA to the HNA-HS fraction for both sample dates. Our results suggest that, in Blanes Bay, flow cytometric signatures of natural communities track their phylogenetic composition.
基于核酸（NA）含量荧光（FL）和细胞大小（如侧向散射，SSC）的代理，通过流式细胞术可区分海洋细菌种群，其生态意义在很大程度上尚不清楚。一些研究表明，高 NA（HNA）含量和高 SSC（HS）的细胞代表群落的活跃成员，而低 NA（LNA）细胞则是同一系统发育群的不活跃成员。但是，细胞分选后的特定组活性测量和系统发育分配表明事实并非如此，特别是在开阔海域的群落中。为了测试不同 NA 亚群的相似程度，以及它们在环境中可能具有相似的生态和生物地球化学作用的程度，我们通过 454 焦磷酸测序分析了三个细胞群（高 NA-高 SC（HNA-HS），高 NA-低 SC（HNA-LS），低 NA（LNA））的系统发育组成在西北地中海沿岸水域（BBMO，布拉内斯湾微生物观测站）的两个不同时期。这三个种群在那里具有反复出现的季节性模式。统计分析表明，夏季和冬季样本有显著差异，重要的是，样本内的分选种群由不同的分类群组成。大多数分类群仅与一个 NA 分数相关，并且 HNA 和 LNA 以及夏季和冬季群落之间的重叠程度（即同时存在于 2 个分数中的 OTU）很小。红杆菌目，SAR116 和拟杆菌门主要构成 HNA 分数，而其他组，如 SAR11 和 SAR86，则主要构成 LNA 分数。除 SAR86 外的γ变形菌对特定的 NA 分数没有明显偏好。对于两个采样日期，从 LNA 到 HNA-HS 分数，多样性都有所增加。我们的结果表明，在布拉内斯湾，自然群落的流式细胞术特征可追踪其系统发育组成。
