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首页> 外文期刊>Applied Microbiology >Effect of Pressure-Induced Changes in the Ionization Equilibria of Buffers on Inactivation of Escherichia coli and Staphylococcus aureus by High Hydrostatic Pressure
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Effect of Pressure-Induced Changes in the Ionization Equilibria of Buffers on Inactivation of Escherichia coli and Staphylococcus aureus by High Hydrostatic Pressure

机译：压力引起的缓冲液电离平衡变化对高静水压力灭活大肠杆菌和金黄色葡萄球菌的影响

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Survival rates of Escherichia coli and Staphylococcus aureus after high-pressure treatment in buffers that had large or small reaction volumes (Δ V °), and which therefore underwent large or small changes in pH under pressure, were compared. At a low buffer concentration of 0.005 M, survival was, as expected, better in MOPS (morpholinepropanesulfonic acid), HEPES, and Tris, whose Δ V ° values are approximately 5.0 to 7.0 cm~(3) mol~(?1), than in phosphate or dimethyl glutarate (DMG), whose Δ V ° values are about ?25 cm~(3) mol~(?1). However, at a concentration of 0.1 M, survival was unexpectedly better in phosphate and DMG than in MOPS, HEPES, or Tris. This was because the baroprotective effect of phosphate and DMG increased much more rapidly with increasing concentration than it did with MOPS, HEPES, or Tris. Further comparisons of survival in solutions of salts expected to cause large electrostriction effects (Na_(2)SO_(4) and CaCl_(2)) and those causing lower electrostriction (NaCl and KCl) were made. The salts with divalent ions were protective at much lower concentrations than salts with monovalent ions. Buffers and salts both protected against transient membrane disruption in E. coli , but the molar concentrations necessary for membrane protection were much lower for phosphate and Na_(2)SO_(4) than for HEPES and NaCl. Possible protective mechanisms discussed include effects of electrolytes on water compressibility and kosmotropic and specific ion effects. The results of this systematic study will be of considerable practical significance in studies of pressure inactivation of microbes under defined conditions but also raise important fundamental questions regarding the mechanisms of baroprotection by ionic solutes.
机译：比较了高压处理后在反应体积大或小（ΔV°）且因此在压力下pH值发生大或小变化的缓冲液中大肠杆菌和金黄色葡萄球菌的存活率。如预期的那样，在0.005 M的低缓冲液浓度下，其MOV（吗啉丙烷磺酸），HEPES和Tris的存活率更好，它们的ΔV°值约为5.0至7.0 cm〜（3）mol〜（？1），与ΔV°值约为？25 cm〜（3）mol〜（？1）的磷酸盐或戊二酸二甲酯（DMG）相比。但是，在0.1 M的浓度下，磷酸盐和DMG的存活率比MOPS，HEPES或Tris的出乎意料地好。这是因为磷酸盐和DMG的压力保护作用随着浓度的增加而比MOPS，HEPES或Tris的保护作用要快得多。进一步比较了预期会引起大的电致伸缩效应的盐溶液（Na_（2）SO_（4）和CaCl_（2））和引起电致伸缩降低的盐溶液（NaCl和KCl）的存活率。具有二价离子的盐在比具有一价离子的盐低得多的浓度下具有保护性。缓冲液和盐都可以防止大肠杆菌中的瞬时膜破坏，但磷酸盐和Na_（2）SO_（4）所需的膜保护摩尔浓度要比HEPES和NaCl低得多。讨论的可能的保护机制包括电解质对水可压缩性的影响以及同渗和特定离子的影响。这项系统研究的结果在确定条件下微生物的压力失活研究中将具有相当大的实际意义，但也提出了有关离子溶质对气压保护的机理的重要基础性问题。

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