Department of Biology, University of South Florida, Tampa, Florida 33620.
Appl Environ Microbiol. 1990 Jun;56(6):1818-24. doi: 10.1128/aem.56.6.1818-1824.1990.
Both naturally occurring marine sediments and artificial sediments were used as supports for natural transformation of marine bacteria. While transformation of Pseudomonas stutzeri ZoBell suspended in artificial seawater was not detected when recipient cells and rifampin resistance DNA were loaded onto sterile sediment columns, transformation could be detected at frequencies 4 to 20 times that of spontaneous resistance when recipient cells and rifampin resistance DNA were loaded onto sterile sediment columns. Treatment of these columns with DNase I reduced transformation frequencies to levels comparable to those of spontaneous-resistance frequencies. Sediments with higher organic contents supported higher frequencies of transformation than did those with lower amounts of organic matter. Transformation was also detected when recipient cells and DNA were loaded on columns prepared from nonsterile sediments, although the frequencies of transformation were lower than when sterile sediments were used. Finally, nonsterilized sediments that were not supplemented with laboratory strains did not support detectable levels of transformation in sediment columns, but when these same sediments were transferred to filters and placed on complex media, transformation was detected at a frequency three times that for spontaneous resistance. This transformation frequency was partially reduced to levels near that for spontaneous resistance by the addition of DNase I to sediment filters. These results indicate that marine sediments facilitate the uptake and expression of exogenous DNA by transformable marine bacteria and that sediments are a more likely niche for natural transformation than the water column in the marine environment.
天然海洋沉积物和人工沉积物都被用作海洋细菌自然转化的载体。当将假单胞菌 ZoBell 悬浮液中的受体细胞和 rifampin 抗性 DNA 加载到无菌沉积物柱上时，未检测到转化，而当将受体细胞和 rifampin 抗性 DNA 加载到无菌沉积物柱上时，转化频率可达到自发抗性频率的 4 到 20 倍。用 DNase I 处理这些柱子可将转化频率降低至与自发抗性频率相当的水平。有机含量较高的沉积物支持更高频率的转化，而有机物质含量较低的沉积物则支持较低频率的转化。当将受体细胞和 DNA 加载到由非无菌沉积物制备的柱子上时，也检测到了转化，尽管转化频率低于使用无菌沉积物时的转化频率。最后，未经过消毒且未补充实验室菌株的沉积物在沉积物柱中不支持可检测水平的转化，但当将这些相同的沉积物转移到过滤器上并置于复杂培养基上时，转化频率达到自发抗性的三倍。向沉积物过滤器中添加 DNase I 可将这种转化频率部分降低至接近自发抗性的水平。这些结果表明，海洋沉积物促进了可转化海洋细菌对外源 DNA 的摄取和表达，并且沉积物比海洋环境中的水柱更有可能成为自然转化的栖息地。
