Alonso Cecilia, Zeder Michael, Piccini Claudia, Conde Daniel, Pernthaler Jakob
Limnological Station, Institute of Plant Biology, Seestr. 187, CH-8802 Kilchberg, Switzerland.
Environ Microbiol. 2009 Apr;11(4):867-76. doi: 10.1111/j.1462-2920.2008.01807.x. Epub 2008 Nov 26.
We studied the population sizes and substrate incorporation patterns of three phylogenetic groups of Betaproteobacteria in a coastal subtropical lagoon that is characterized by a sharp transition from humic freshwater to turbid brackish water. Various cellular processes were addressed by short-term incubations with four radiolabelled compounds and microautoradiographic assessment of substrate incorporation. Group-specific differences in the abundances and the respective physiological state of the three populations were observed upon transfer from the humic-rich compartment to the main body of the lagoon (estimated at 1-2 days). Members of the clade B of Polynucleobacter (PnecB) experienced only an insignificant change in cell numbers, but displayed a general metabolic downshift, carbon metabolism (glucose incorporation) being most affected. By contrast, bacteria from the closely related Polynucleobacter C clade (PnecC) clearly differed in total abundances and in the numbers of DNA-synthesizing or glucose incorporating cells. At the same time, PnecC bacteria maintained comparable levels of protein synthesis (leucine uptake) in both lagoon compartments, and the proportion of cells incorporating N-acetylglucosamine was even higher in the main body of the lagoon. Members of the R-BT lineage showed little changes in cell numbers, DNA synthesis and carbon metabolism. Altogether, the observed patterns of substrate metabolism suggest that different bacterial populations in the lagoon undergo specific physiological adjustments in response to changing environmental conditions.
我们研究了β-变形菌纲三个系统发育类群在一个亚热带沿海泻湖中的种群大小和底物掺入模式,该泻湖的特点是从腐殖质丰富的淡水急剧过渡到浑浊的微咸水。通过与四种放射性标记化合物进行短期培养以及对底物掺入进行显微放射自显影评估,探讨了各种细胞过程。在从富含腐殖质的区域转移到泻湖主体(估计为1 - 2天)后,观察到这三个种群在丰度和各自生理状态上的类群特异性差异。多核杆菌B进化枝(PnecB)的成员细胞数量仅发生了微不足道的变化,但总体代谢出现了下降,碳代谢(葡萄糖掺入)受到的影响最大。相比之下,来自密切相关的多核杆菌C进化枝(PnecC)的细菌在总丰度以及DNA合成或葡萄糖掺入细胞数量方面存在明显差异。与此同时,PnecC细菌在两个泻湖区域的蛋白质合成(亮氨酸摄取)水平相当,并且在泻湖主体中掺入N - 乙酰葡糖胺的细胞比例甚至更高。R - BT谱系的成员在细胞数量、DNA合成和碳代谢方面变化不大。总之,观察到的底物代谢模式表明,泻湖中的不同细菌种群会根据不断变化的环境条件进行特定的生理调节。