Growth rate of the major phylogenetic bacterial groups in the Delaware estuary
Growth rate of the major phylogenetic bacterial groups in the Delaware estuary
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DOI：
10.4319/lo.2004.49.5.1620
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发表时间：
2004-09
影响因子：
4.5
通讯作者：
T. Yokokawa;T. Nagata;M. Cottrell;D. Kirchman
中科院分区：
文献类型：
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作者：
T. Yokokawa;T. Nagata;M. Cottrell;D. Kirchman
细菌群落的系统发育组成随着河口盐度梯度的变化而变化，其中一个显著的模式是α-和β-蛋白细菌分别在咸水区和淡水区的流行。我们测试了自下而上的力量(底物供应)控制特拉华州河口细菌群落组成的这些和其他变化的假设。我们采用稀释培养和荧光原位杂交相结合的方法，测量了河口低盐度和高盐度地区四个主要的浮游细菌系统发生类群(α、β和伽马蛋白细菌以及细胞吞噬黄杆菌类群)的生物量和生长率。特定于群体的生长率随地点和季节的不同而变化很大，可能远远超过细菌总数的生长率(最高可达四倍)。表现出最高生长速度的系统发育类群包括低盐度和高盐度站的阿尔法和伽马蛋白细菌以及低盐度站的贝塔蛋白细菌。这些数据有助于解释淡水地区β-变形杆菌的高丰度，但自下而上的控制似乎只解释了细菌群落的部分变异性。产量和生物量之间的关系表明，低盐度地点的细菌群落受底物供应控制，而高盐度地点的细菌死亡率似乎更重要。我们的数据表明，特定于群体的生长率是检验个体群体的竞争优势和河口环境中细菌群落的调节模式的有用参数。
The phylogenetic composition of bacterial communities varies along the salinity gradient of estuaries, one notable pattern being the prevalence of alpha‐ and beta‐proteobacteria in salt‐ and freshwater regions, respectively. We tested the hypothesis that bottom‐up forces (substrate supply) control these and other changes in bacterial community composition in the Delaware estuary. We measured the biomass and growth rate of four major phylogenetic groups of bacterioplankton (alpha‐, beta‐, and gamma‐proteobacteria and the Cytophaga‐Flavobacter cluster) in low‐ and high‐salinity regions of the estuary by the dilution culture approach combined with fluorescent in situ hybridization with rRNA‐targeted probes. Group‐specific growth rates were highly variable depending on location and season and could far exceed (up to nearly fourfold) the growth rates of total bacteria. The phylogenetic groups that exhibited the highest growth rates included alpha‐ and gamma‐proteobacteria at both low‐ and high‐salinity stations and betaproteobacteria at a low‐salinity station. These data help to explain the high abundance of beta‐proteobacteria in the freshwater region, but bottom up controls appear to account only partly for the variability in bacterial communities. The relationship between production and biomass suggested that bacterial communities at the low‐salinity site were controlled by substrate supply, whereas bacterial mortality appeared to be more important at the high‐salinity site. Our data demonstrate that group‐specific growth rates are useful parameters for examining the competitive advantages of individual groups and the mode of regulation of bacterial communities in estuarine environments.