Amino acids improve acid tolerance and internal pH maintenance in Bacillus cereus ATCC14579 strain.
Amino acids improve acid tolerance and internal pH maintenance in Bacillus cereus ATCC14579 strain.
复制标题
DOI：
10.1016/j.fm.2010.09.003
复制
发表时间：
2011-05
影响因子：
5.3
通讯作者：
Khadidja Senouci-Rezkallah;P. Schmitt;M. Jobin
中科院分区：
文献类型：
--
作者：
Khadidja Senouci-Rezkallah;P. Schmitt;M. Jobin
本研究调查了蜡样芽孢杆菌 ATCC14579 菌株的耐酸反应 (ATR) 中谷氨酸、精氨酸和赖氨酸依赖性系统的参与情况。细胞在外部 pH (pHe) 7.0 和 5.5 的恒化器中生长。与在 pH 7.0（未适应）下生长的细胞相比，在 pH 4.0 下酸休后，在 pH 5.5（酸适应）下生长的细胞中，群体减少受到强烈限制，这表明在低 pH 下生长的蜡样芽胞杆菌细胞能够诱导显着的 ATR。谷氨酸、精氨酸和赖氨酸分别增强了未适应细胞对 1-log 或 2-log 群体的 pH 4.0 酸冲击的抵抗力。氨基酸对酸适应细胞的耐酸性没有可检测到的影响。与酸适应细胞相比，pH 4.0 的酸冲击导致未适应细胞的内部 pH (pHi) 显着下降。当存在谷氨酸、精氨酸或赖氨酸的情况下实现酸休克时，与不存在氨基酸的情况下的 pHi (4.88) 相比，pHi 保持在较高的值 (分别为 6.31、6.69 或 6.99)。无论条件如何，酸适应细胞的 pHiat 都维持在 6.4 左右。胍丁胺（精氨酸脱羧酶的竞争性抑制剂）对蜡样芽孢杆菌细胞在酸休克期间存活和维持 pH 的能力有负面影响。我们的数据表明，蜡样芽胞杆菌能够在低 pH 条件下生长期间诱导 ATR。这种适应取决于 pHi 稳态，并且在谷氨酸、精氨酸和赖氨酸存在的情况下会增强。因此，评估蜡样芽孢杆菌的致病性必须考虑其适应酸胁迫的能力。
This study investigated the involvement of glutamate-, arginine- and lysine-dependent systems in the Acid Tolerance Response (ATR) of Bacillus cereus ATCC14579 strain. Cells were grown in a chemostat at external pH (pHe) 7.0 and 5.5. Population reduction after acid shock at pH 4.0 was strongly limited in cells grown at pH 5.5 (acid-adapted) compared with cells grown at pH 7.0 (unadapted), indicating that B. cereus cells grown at low pHewere able to induce a marked ATR. Glutamate, arginine and lysine enhanced the resistance of unadapted cells to pH 4.0 acid shock of 1-log or 2-log populations, respectively. Amino acids had no detectable effect on acid resistance in acid-adapted cells. An acid shock at pH 4.0 resulted in a marked drop in internal pH (pHi) in unadapted cells compared with acid-adapted cells. When acid shock was achieved in the presence of glutamate, arginine or lysine, pHiwas maintained at higher values (6.31, 6.69 or 6.99, respectively) compared with pHiin the absence of amino acids (4.88). Acid-adapted cells maintained their pHiat around 6.4 whatever the condition. Agmatine (a competitive inhibitor of arginine decarboxylase) had a negative effect on the ability of B. cereus cells to survive and maintain their pHiduring acid shock. Our data demonstrate that B. cereus is able to induce an ATR during growth at low pH. This adaptation depends on pHihomeostasis and is enhanced in the presence of glutamate, arginine and lysine. Hence evaluations of the pathogenicity of B. cereus must take into account its ability to adapt to acid stress.