Spilimbergo Sara, Bertucco Alberto, Basso Giuseppe, Bertoloni Giulio
Department of Material Engineering and Industrial Technologies, University of Trento, via Mesiano 77, Trento, Italy.
Biotechnol Bioeng. 2005 Nov 20;92(4):447-51. doi: 10.1002/bit.20606.
In this study, we consider the effect of carbon dioxide (CO(2)) on the intracellular and extracellular pH of a saline solution of a test-microorganisms Bacillus subtilis. The cytoplasmatic pH was determined by means of a flow cytometry with the fluorescent probe 5(and 6-)-carboxyfluorescein ester (cFSE). The physiological suspension of cells with the addition of the probe was first exposed to high pressure CO(2) for 5 min at different temperatures. The flow cytometry analysis indicated an intracellular depletion inside the cell caused by the action of CO(2), down to 3, the depletion being dependent on inactivation ratio. In addition, the extracellular pH was determined theoretically by means of the statistical associated fluid theory equation of state (SAFT EOS): it was demonstrated that CO(2) under pressure dissolves into liquid phase and acidifies the medium down to 3 at 80 bar and 303.15K. The results show a strong influence between extracellular and intracellular pH, and lead to the conclusion that a strong reduction of the pH homeostasis of the cell can be claimed as one of the most probable cause of inactivation of CO(2) pasteurization.
在本研究中，我们考察了二氧化碳（CO₂）对测试微生物枯草芽孢杆菌盐溶液细胞内和细胞外pH值的影响。通过使用荧光探针5（和6 -）-羧基荧光素酯（cFSE）的流式细胞术测定细胞质pH值。首先将添加了探针的细胞生理悬浮液在不同温度下于高压CO₂中暴露5分钟。流式细胞术分析表明，CO₂的作用导致细胞内pH值降低至3，这种降低取决于失活率。此外，通过统计缔合流体理论状态方程（SAFT EOS）从理论上测定细胞外pH值：结果表明，在80巴和303.15K条件下，受压的CO₂溶解进入液相并使培养基酸化至pH值为3。结果显示细胞外和细胞内pH值之间存在强烈影响，并得出结论：细胞pH值稳态的强烈降低可被认为是CO₂巴氏杀菌失活最可能的原因之一。
