Contribution of cardiolipin synthase to the salt resistance

  • Meng-Ju Melody Tsai, University of Tsukuba, Japan
  • Kazuya Morikawa, University of Tsukuba, Japan
  • Ryosuke Ohniwa, University of Tsukuba, Japan
  • Toshiko Ohta, University of Tsukuba, Japan
  • Shinji Saito, University of Tsukuba, Japan
  • Hideo Hayashi, Chugoku Gakuen University, Japan

    • Objective
    Cardiolipin markedly increases under high NaCl concentration. This study aimed to identify the cardiolipin synthase by molecular genetic method, and to reveal the importance of cardiolipin in the survival under high NaCl concentration.
    Methods
    Two homologous of the Bacillus subtilis cardiolipin synthase gene (cls) were deleted from Staphylococcus aureus RN4220. The mutants were subjected to TLC analysis to examine the lipid compositions, and to the susceptibility test for high concentration of NaCl.
    Results
    One of the homologues was the bona fide cls gene. Its mutant grew slowly than RN4220 in the presence of 15% NaCl, but the final optical density was not different from RN4220 after prolonged incubation. However, the cfu value of the cls mutant was significantly lower. The NaCl MIC value of the mutant was not different from RN4220, while the survival rate of the mutant against the exposure to 25% NaCl was decreased.
    Conclusions
    Cardiolipin is not essential to grow under high salt concentration, but plays an important role in the survival.