Weinbauer Markus G, Christen Richard, Höfle Manfred G
GBF--German Research Centre for Biotechnology, Department of Environmental Microbiology, Mascheroder Weg 1, D-38124, Braunschweig, Germany.
Microb Ecol. 2006 Apr;51(3):336-44. doi: 10.1007/s00248-006-9028-x. Epub 2006 Apr 6.
We investigated the growth response of the heterotrophic prokaryotic community focusing on Vibrio- and Rhodobacter-related populations (SRF3) to variation in the availability of dissolved organic matter (DOM), population density-dependent effects, and prokaryotic virus (phage) infection in coastal and offshore waters of the NW Mediterranean Sea. We tested the response of the prokaryotic community to three different DOM fractions prepared by ultrafiltration. One of the DOM fractions contained phages (<0.2 m), a second was virus-free (<100 kDa), and a third contained only low molecular weight (<1 kDa). The proportion of Vibrio and SRF3 populations as determined by fluorescent in situ hybridization in the community ranged from <1 to 6.2% and from 3.2 to 6.3%, respectively. Based on changes in cell numbers, growth rates ranged from 2.1 to 3.1 day(-1) for Vibrio and from 0.8 to 1.2 day(-1) for SRF3. Growth rates of Vibrio were similar or higher than those of the total prokaryotic community, whereas the ability of Vibrio to use high molecular weight (HMW) DOM and the responses to additions of phage-rich material were lower. Growth rates of SRF3 were lower than that of the community. Susceptibility to infection of SRF3 was sometimes lower than in the community, whereas the growth stimulation of HMW DOM was similar or lower. Reducing the cell concentrations of the prokaryotic community by dilution stimulated the overall growth of the community, including that of its constituent Vibrio and SRF3 populations, but the effect was smaller on the SRF3 and greater on Vibrio populations than for the total community. Comparisons with the community also revealed that life strategy traits of bacterial populations differed between coastal and offshore waters. Overall, our data suggest that Vibrio is an r-strategist or opportunistic population in the NW Mediterranean Sea, whereas SRF3 is a K-strategist or equilibrium population.
我们研究了异养原核生物群落的生长响应，重点关注与弧菌和红杆菌相关的种群（SRF3）对地中海西北部沿海和近海水域中溶解有机物（DOM）可利用性变化、种群密度依赖性效应以及原核病毒（噬菌体）感染的响应。我们测试了原核生物群落对通过超滤制备的三种不同DOM组分的响应。其中一种DOM组分含有噬菌体（<0.2μm），第二种无病毒（<100 kDa），第三种仅含有低分子量（<1 kDa）物质。通过荧光原位杂交测定，群落中弧菌和SRF3种群的比例分别为<1%至6.2%和3.2%至6.3%。基于细胞数量的变化，弧菌的生长速率为2.1至3.1天⁻¹，SRF3的生长速率为0.8至1.2天⁻¹。弧菌的生长速率与整个原核生物群落的相似或更高，而弧菌利用高分子量（HMW）DOM的能力以及对添加富含噬菌体物质的响应较低。SRF3的生长速率低于群落。SRF3对感染的易感性有时低于群落，而HMW DOM对其生长的刺激作用相似或更低。通过稀释降低原核生物群落的细胞浓度刺激了群落的总体生长，包括其组成的弧菌和SRF3种群，但对SRF3的影响较小，对弧菌种群的影响比对整个群落的影响更大。与群落的比较还表明，沿海和近海水域细菌种群的生活策略特征存在差异。总体而言，我们的数据表明，在西北地中海，弧菌是r策略者或机会主义种群，而SRF3是K策略者或平衡种群。
