Stewart G J, Sinigalliano C D
Department of Biology, University of South Florida, Tampa 33620.
Antonie Van Leeuwenhoek. 1991 Jan;59(1):19-25. doi: 10.1007/BF00582115.
Both the soil isolate, Pseudomonas stutzeri JM300, and the marine isolate, Pseudomonas stutzeri strain ZoBell, have been shown previously to be naturally transformable. This study reports the detection of genetic exchange by natural transformation between these two isolates. Transformation frequency was determined by filter transformation procedures. Three independent antibiotic resistance loci were used as chromosomal markers to monitor this exchange event: resistance to rifampicin, streptomycin, and nalidixic acid. The maximum frequencies of transformation were on the order of 3.1 to 3.8 x 10(-6) transformants per recipient; frequencies over an order of magnitude greater than those for spontaneous antibiotic resistance, although they are lower than those observed for soil:soil or marine:marine strain crosses. This exchange was inhibited by DNase I. Transformation was observed between soil and marine strains, both by filter transformation using purified DNA solutions and when transforming DNA was added in the form of viable donor cells. The results from this study support the close genetic relationship between P. stutzeri JM300 and P. stutzeri strain ZoBell. These results also further validate the utility of P. stutzeri as a benchmark organism for modeling gene transfer by natural transformation in both soil and marine habitats.
之前已证明土壤分离株施氏假单胞菌JM300和海洋分离株施氏假单胞菌菌株佐贝尔都具有自然转化能力。本研究报告了这两种分离株之间通过自然转化进行基因交换的检测情况。转化频率通过滤膜转化程序来确定。使用三个独立的抗生素抗性位点作为染色体标记来监测这一交换事件：对利福平、链霉素和萘啶酸的抗性。转化的最大频率约为每受体3.1至3.8×10⁻⁶个转化子；该频率比自发抗生素抗性的频率高一个数量级以上，尽管低于土壤菌株间或海洋菌株间杂交所观察到的频率。这种交换受到DNA酶I的抑制。在土壤菌株和海洋菌株之间观察到了转化，这既通过使用纯化DNA溶液的滤膜转化实现，也通过以活的供体细胞形式添加转化DNA实现。本研究结果支持施氏假单胞菌JM300和施氏假单胞菌菌株佐贝尔之间存在密切的遗传关系。这些结果还进一步验证了施氏假单胞菌作为在土壤和海洋生境中通过自然转化进行基因转移建模的基准生物的实用性。
