Weinbauer MG, Hofle MG
GBF-National Research Center of Biotechnology, AG Microbial Ecology, D-38124 Braunschweig, Germany.
Appl Environ Microbiol. 1998 Oct;64(10):3776-83. doi: 10.1128/AEM.64.10.3776-3783.1998.
Monoclonal antibodies and epifluorescence microscopy were used to determine the depth distribution of two indigenous bacterial populations in the stratified Lake Plusssee and characterize their life strategies. Populations of Comamonas acidovorans PX54 showed a depth distribution with maximum abundances in the oxic epilimnion, whereas Aeromonas hydrophila PU7718 showed a depth distribution with maximum abundances in the anoxic thermocline layer (metalimnion), i. e., in the water layer with the highest microbial activity. Resistance of PX54 to protist grazing and high metabolic versatility and growth rate of PU7718 were the most important life strategy traits for explaining the depth distribution of the two bacterial populations. Maximum abundance of PX54 was 16,000 cells per ml, and maximum abundance of PU7718 was 20,000 cells per ml. Determination of bacterial productivity in dilution cultures with different-size fractions of dissolved organic matter (DOM) from lake water indicates that low-molecular-weight (LMW) DOM is less bioreactive than total DOM (TDOM). The abundance and growth rate of PU7718 were highest in the TDOM fractions, whereas those of PX54 were highest in the LMW DOM fraction, demonstrating that PX54 can grow well on the less bioreactive DOM fraction. We estimated that 13 to 24% of the entire bacterial community and 14% of PU7718 were removed by viral lysis, whereas no significant effect of viral lysis on PX54 could be detected. Growth rates of PX54 (0.11 to 0.13 h-1) were higher than those of the entire bacterial community (0.04 to 0.08 h-1) but lower than those of PU7718 (0.26 to 0.31 h-1). In undiluted cultures, the growth rates were significantly lower, pointing to density effects such as resource limitation or antibiosis, and the effects were stronger for PU7718 and the entire bacterial community than for PX54. Life strategy characterizations based on data from literature and this study revealed that the fast-growing and metabolically versatile A. hydrophila PU7718 is an r-strategist or opportunistic population in Lake Plusssee, whereas the grazing-resistant C. acidovorans PX54 is rather a K-strategist or equilibrium population.
利用单克隆抗体和落射荧光显微镜来确定分层的普卢斯湖（Lake Plusssee）中两个本地细菌种群的深度分布，并描述它们的生存策略。嗜酸丛毛单胞菌（Comamonas acidovorans）PX54种群的深度分布显示，在有氧的湖面温水层中丰度最高，而嗜水气单胞菌（Aeromonas hydrophila）PU7718的深度分布则显示，在缺氧的温跃层（斜温层）中丰度最高，即处于微生物活性最高的水层中。PX54对原生生物捕食的抗性以及PU7718的高代谢多样性和生长速率是解释这两个细菌种群深度分布的最重要生存策略特征。PX54的最大丰度为每毫升16,000个细胞，PU7718的最大丰度为每毫升20,000个细胞。对来自湖水的不同大小溶解有机物（DOM）组分的稀释培养物中的细菌生产力测定表明，低分子量（LMW）DOM的生物反应性低于总DOM（TDOM）。PU7718在TDOM组分中的丰度和生长速率最高，而PX54在LMW DOM组分中的丰度和生长速率最高，这表明PX54能够在生物反应性较低的DOM组分上良好生长。我们估计，整个细菌群落的13%至24%以及PU7718的14%被病毒裂解去除，而未检测到病毒裂解对PX54有显著影响。PX54的生长速率（0.11至0.13 h⁻¹）高于整个细菌群落（0.04至0.08 h⁻¹），但低于PU7718（0.26至0.31 h⁻¹）。在未稀释的培养物中，生长速率显著较低，这表明存在诸如资源限制或抗生等密度效应，并且这些效应对于PU7718和整个细菌群落比对PX54更强。基于文献数据和本研究的生存策略特征表明，生长迅速且代谢多样的嗜水气单胞菌PU7718是普卢斯湖中的r策略者或机会主义种群，而抗捕食的嗜酸丛毛单胞菌PX54更像是K策略者或平衡种群。
