Salmonella typhimurium SR-11 is extremely virulent at a dose as low as 105 colony forming units (cfu) when administered perorally to BALB/c mice. Utilizing mini-transposon mutagenesis, a mutant of S. typhimurium SR-11 was isolated that was unable to utilize oleate and citrate as carbon sources. This mutant, designated S. typhimurium SR-11 Fad- (Fatty acid), was found to utilize sugars under cyalcrp control as sole carbon sources, suggesting that the mutation is not in either of these genes. In addition, SR-11 Fad- utilized pyruvate and succinate, but was unable to utilize either acetate or isocitrate as sole carbon source. In contrast to SR-11, SR-11 Fad- was found to be avirulent, i.e. BALB/c mice were completely healthy after oral infection with 109 S. typhimurium SR-11 Fad- cells. Moreover, 21 days after SR-11 Fad- infection, BALB/c mice were found to be protected against an oral challenge with 109 cells of S. typhimurium SR-11.
Utley, M., Franklin, D. P., Krogfelt, K. A., Laux, D. C., & Cohen, P. S. (1998). A Salmonella typhimurium mutant unable to utilize fatty acids and citrate is avirulent and immunogenic in mice. FEMS Microbiology Letters, 163(2), 129–134. https://doi.org/10.1016/S0378-1097(98)00162-1