Hahn MW, Höfle MG
GBF-National Research Center of Biotechnology, AG Microbial Ecology, D-38124 Braunschweig, Germany.
Appl Environ Microbiol. 1998 May 1;64(5):1910-8. doi: 10.1128/AEM.64.5.1910-1918.1998.
The response of the bacterial strains Comamonas acidovorans PX54 (beta subclass of the class Proteobacteria) and Vibrio strain CB5 (gamma subclass of the class Proteobacteria) to grazing by the bacterivorous flagellate Ochromonas sp. was examined in one-stage chemostat experiments under conditions of low growth rates with a complex carbon source. The two bacterial strains were cultured together; they were cultured without flagellates in the first phase of the experiments and in the presence of the flagellates in the second phase. Monoclonal and polyclonal antibodies were used to determine the numbers and sizes of C. acidovorans PX54 and Vibrio strain CB5 cells. The flagellates caused strong changes in total bacterial cell numbers, in the relative abundances of the individual bacterial strains, and in bacterial cell size distribution. Vibrio strain CB5 dominated the total bacterial cell numbers during the flagellate-free phase of the experiments with a relative abundance of 93%, but this declined to 33% after inoculation with the flagellate. In contrast to Vibrio strain CB5, C. acidovorans PX54 responded to grazing with a strong expansion of cell length distribution toward large, filamentous cells. These changes in cell morphology resulted in a high percentage of inedible cells in the C. acidovorans PX54 population but not in the Vibrio strain CB5 population, which caused the observed change in the relative abundances of the strains. Batch culture experiments without the flagellate demonstrated that the elongation of C. acidovorans PX54 cells was dependent on their growth rate. This indicates that the occurrence of filamentous C. acidovorans PX54 cells is not a direct response to chemical stimuli released by the flagellates but rather a response to increased growth rates due to flagellate grazing.
在以复合碳源为培养基、低生长速率条件下的单级恒化器实验中，研究了食酸丛毛单胞菌PX54（变形菌纲β亚纲）和弧菌菌株CB5（变形菌纲γ亚纲）对噬菌性鞭毛虫赭纤虫的捕食反应。将这两种细菌菌株共同培养；在实验的第一阶段，它们在没有鞭毛虫的情况下培养，在第二阶段则在有鞭毛虫的情况下培养。使用单克隆抗体和多克隆抗体来确定食酸丛毛单胞菌PX54和弧菌菌株CB5细胞的数量和大小。鞭毛虫导致细菌总细胞数、各细菌菌株的相对丰度以及细菌细胞大小分布发生了显著变化。在无鞭毛虫阶段的实验中，弧菌菌株CB5在细菌总细胞数中占主导地位，相对丰度为93%，但接种鞭毛虫后，这一比例降至33%。与弧菌菌株CB5不同，食酸丛毛单胞菌PX54对捕食的反应是细胞长度分布向大型丝状细胞强烈扩展。细胞形态的这些变化导致食酸丛毛单胞菌PX54群体中不可食用细胞的比例很高，但弧菌菌株CB5群体中并非如此，这就导致了观察到的菌株相对丰度的变化。没有鞭毛虫的分批培养实验表明，食酸丛毛单胞菌PX54细胞的伸长取决于其生长速率。这表明丝状食酸丛毛单胞菌PX54细胞的出现不是对鞭毛虫释放的化学刺激的直接反应，而是对由于鞭毛虫捕食导致的生长速率增加的反应。
