Williams H G, Day M J, Fry J C, Stewart G J
School of Pure and Applied Biology, College of Cardiff, University of Wales, United Kingdom.
Appl Environ Microbiol. 1996 Aug;62(8):2994-8. doi: 10.1128/aem.62.8.2994-2998.1996.
Natural transformation was demonstrated in unenclosed experiments incubated in river epilithon. Strains of Acinetobacter calcoaceticus were transformed to prototrophy by either free DNA (lysates) or live donor cells. The sources of transforming DNA and recipient culture were immobilized on filters, secured to stones, and incubated midstream in the river. The transfer frequency generally increased with temperature. No transfer was detected in the river Taff below 10 degrees C. The age of the recipient culture affected the transformation frequencies in situ but did not significantly affect the transfer frequency on laboratory media. Transformation of recipient cultures which had been incorporated into the natural epilithic biofilm and transformation of the plasmid pQM17 in situ were also demonstrated. This study provides the first direct evidence of natural transformation in situ of bacteria incorporated into an indigenous community.
在河流表生生物膜中进行的开放式实验证明了自然转化现象。乙酸钙不动杆菌菌株可通过游离DNA（裂解物）或活供体细胞转化为原养型。转化DNA的来源和受体培养物被固定在滤膜上，固定在石头上，并在河流中游进行培养。转移频率通常随温度升高而增加。在10摄氏度以下的塔夫河中未检测到转移现象。受体培养物的菌龄影响原位转化频率，但对实验室培养基上的转移频率没有显著影响。还证明了已整合到天然表生生物膜中的受体培养物的转化以及质粒pQM17的原位转化。这项研究提供了第一个直接证据，证明了融入本地群落的细菌在原位发生自然转化。
