抄録
Ralstonia solanacearum is a soil-borne pathogen that causes bacterial wilt disease in many plants worldwide. The wild-type strain undergoes a phenotypic conversion (PC) spontaneously, shifting from a pathogenic to a non-pathogenic form. There are still uncertainties about the growth behavior of the wild-type strains and PC mutants when both strains are mixed in cultures. We investigated the bacterial competition between both strains in liquid medium. When bacteria were mixed and cultured statically in BG broth, the growth of only the wild-type strain was reduced at the later period (16–24 d) of culture. However, this bacterial competition was not observed in 100-fold diluted BG broth, suggesting that there are factors other than competition for nutrients. When each strain was individually inoculated in bacterial culture filtrates, the PC mutant could grow in the culture filtrates. However, the wild-type strain could not grow only in the culture filtrate of the PC mutant. The growth inhibition of the wild-type strain was also observed in the heat-treated culture filtrate of the PC mutant. These results indicate that the bacterial competition between the wild-type strain and the PC mutant in BG broth was due to changes in the culture components by the PC mutant.
