Ahmer B M, Tran M, Heffron F
Department of Molecular Microbiology and Immunology, Oregon Health Sciences University, Portland, Oregon 97201-3098, USA.
J Bacteriol. 1999 Feb;181(4):1364-8. doi: 10.1128/JB.181.4.1364-1368.1999.
Most isolates of Salmonella enterica serovar Typhimurium contain a 90-kb virulence plasmid. This plasmid is reported to be mobilizable but nonconjugative. However, we have determined that the virulence plasmid of strains LT2, 14028, and SR-11 is indeed self-transmissible. The plasmid of strain SL1344 is not. Optimal conjugation frequency requires filter matings on M9 minimal glucose plates with a recipient strain lacking the virulence plasmid. These conditions result in a frequency of 2.9 x 10(-4) transconjugants/donor. Matings on Luria-Bertani plates, liquid matings, or matings with a recipient strain carrying the virulence plasmid reduce the efficiency by up to 400-fold. Homologs of the F plasmid conjugation genes are physically located on the virulence plasmid and are required for the conjugative phenotype.
大多数肠炎沙门氏菌鼠伤寒血清型菌株都含有一个90kb的毒力质粒。据报道，该质粒是可移动的，但不能接合转移。然而，我们已经确定LT2、14028和SR-11菌株的毒力质粒确实是自我传递的。而SL1344菌株的质粒则不是。最佳接合频率需要在M9最小葡萄糖平板上与缺乏毒力质粒的受体菌株进行滤膜交配。这些条件下产生的转接合子频率为2.9×10⁻⁴个/供体。在Luria-Bertani平板上进行交配、液体交配或与携带毒力质粒的受体菌株进行交配，效率会降低多达400倍。F质粒接合基因的同源物在物理位置上位于毒力质粒上，是接合表型所必需的。
