Open AccessAdaptive responses of Bacillus cereus ATCC 14579 cells upon exposure to acid conditions involve ATP ase activity to maintain their internal pH
Author(s) -
SenouciRezkallah Khadidja,
Jobin Michel P.,
Schmitt Philippe
Publication year - 2015
Publication title -
microbiologyopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.881
H-Index - 36
ISSN - 2045-8827
DOI - 10.1002/mbo3.239
Subject(s) - bacillus cereus , nigericin , valinomycin , biochemistry , population , chemistry , cereus , lysis , biology , bacteria , membrane potential , genetics , demography , membrane , sociology
This study examined the involvement of ATP ase activity in the acid tolerance response ( ATR ) of Bacillus cereus ATCC 14579 strain. In the current work, B. cereus cells were grown in anaerobic chemostat culture at external pH ( pH e ) 7.0 or 5.5 and at a growth rate of 0.2 h −1 . Population reduction and internal pH ( pH i ) after acid shock at pH 4.0 was examined either with or without ATP ase inhibitor N,N’ ‐dicyclohexylcarbodiimide ( DCCD ) and ionophores valinomycin and nigericin. Population reduction after acid shock at pH 4.0 was strongly limited in cells grown at pH 5.5 (acid‐adapted cells) compared with cells grown at pH 7.0 (unadapted cells), indicating that B. cereus cells grown at low pH e were able to induce a significant ATR and Exercise‐induced increase in ATP ase activity. However, DCCD and ionophores had a negative effect on the ability of B . cereus cells to survive and maintain their pH i during acid shock. When acid shock was achieved after DCCD treatment, pH i was markedly dropped in unadapted and acid‐adapted cells. The ATP ase activity was also significantly inhibited by DCCD and ionophores in acid‐adapted cells. Furthermore, transcriptional analysis revealed that atpB ( ATP beta chain) transcripts was increased in acid‐adapted cells compared to unadapted cells before and after acid shock. Our data demonstrate that B. cereus is able to induce an ATR during growth at low pH . These adaptations depend on the ATP ase activity induction and pH i homeostasis. Our data demonstrate that the ATP ase enzyme can be implicated in the cytoplasmic pH regulation and in acid tolerance of B. cereus acid‐adapted cells.