Isolation and phylogenetic analysis of aerobic copiotrophic ultramicrobacteria from urban soil
Isolation and phylogenetic analysis of aerobic copiotrophic ultramicrobacteria from urban soil
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DOI：
10.2323/jgam.44.75
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发表时间：
1998-02-01
影响因子：
1.2
通讯作者：
Hiraishi, A
中科院分区：
文献类型：
--
作者：
Iizuka, T;Yamanaka, S;Hiraishi, A
通过直接平板法和膜过滤富集技术，从污染的城市土壤中分离出自由生活的、需氧的、共养的超微细菌（UMB），它们通过0.45 μ m膜过滤器，细胞体积小于0.3 μ m（3）。后一种方法从土壤中回收UMB的效率远高于前一种方法。所有UMB分离株在复杂营养培养基或化学成分确定的培养基中均生长良好，倍增时间小于6小时。通过扫描电子显微镜和具有图像分析的落射荧光显微镜测量，UMB分离物的平均细胞体积范围为0.07至0.22 μ m（3）。在生长的指数期细胞的大小比在一般的静止生长阶段。超薄切片电子显微镜的UMB菌株的代表表明，他们有完整的细胞壁结构，像典型的革兰氏阴性或阳性细菌。表型研究和系统发育分析的基础上的16S rDNA序列表明，UMB菌株被分为三个主要群体，β和γ亚类的变形菌和放线菌（高G+C DNA组的革兰氏阳性菌）。然而，这些分离株都没有被分配到任何以前已知的物种。这些结果表明，自由生活，相对快速增长，共生UMB菌株迄今尚未描述广泛分布在陆地环境，包括城市土壤。
Free-living, aerobic, copiotrophic ultramicrobacteria (UMB) that passed through a 0.45 mu m membrane filter and had a cell volume of less than 0.3 mu m(3) were isolated from polluted urban soil by using both the direct plating method and the membrane-filter enrichment technique. The efficiency of recovering UMB from the soil was much higher in the latter method than in the former. All of the UMB isolates grew well with a doubling time of less than 6 h either in a complex nutrient medium or a chemically defined medium. The average cell volumes of the UMB isolates, as measured by scanning electron microscopy and epifluorescent microscopy with an image analysis, ranged from 0.07 to 0.22 mu m(3). The cell size was larger at the exponential phase of growth than at the stationary growth stage in general. Ultrathin-section electron microscopy of representatives of the UMB isolates showed that they had complete cell wall structures like typical Gram-negative or -positive bacteria. Phenotypic studies and phylogenetic analyses on the basis of 16S rDNA sequences showed that the UMB isolates were classified into three major groups, the beta and gamma subdivisions of the Proteobacteria and the Actinobacteria (the high G+C DNA group of Gram-positives). However, none of these isolates were assigned to any previously known species. These results demonstrate that free-living, relatively fast-growing, copiotrophic UMB strains undescribed so far are widely distributed in terrestrial environments, including urban soil.