Lactic acid permeabilizes gram-negative bacteria by disrupting the outer membrane
Lactic acid permeabilizes gram-negative bacteria by disrupting the outer membrane
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DOI：
10.1128/aem.66.5.2001-2005.2000
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发表时间：
2000-05-01
影响因子：
4.4
通讯作者：
Helander, IM
中科院分区：
文献类型：
--
作者：
Alakomi, HL;Skyttä, E;Helander, IM
利用荧光探针摄取测定和溶菌敏化研究了乳酸对大肠杆菌 O157:H7、铜绿假单胞菌和鼠伤寒沙门氏菌外膜通透性的影响。出于控制目的，使用 EDTA（一种通过螯合作用的透化剂）和盐酸进行了类似的测定，后者的 pH 值与乳酸，并且还有 KCN 存在。 5 mM (pH 4.0) 乳酸已在每个物种中引起显着的透化，荧光测定中的效果比 EDTA 或 HCl 更强。在 KCN 存在下获得了类似的结果，但铜绿假单胞菌除外，在 KCN 存在下观察到 HCl 的作用增加。乳酸和盐酸的透化作用被 MgCl2 部分消除。乳酸比 HCl 更有效地使大肠杆菌和鼠伤寒血清型对十二烷基硫酸钠 (SDS) 的裂解作用敏感，而两种酸都使铜绿假单胞菌对 SDS 和 Triton X-100 敏感。乳酸和HCl 可以有效地使铜绿假单胞菌对溶菌酶敏感。这些酸从鼠伤寒血清型中释放出相当比例的脂多糖；通过电泳和脂肪酸分析对释放的物质进行分析表明，在从外膜释放脂多糖方面，乳酸比 EDTA 或 HCl 更具活性。因此，乳酸除了因降低 pH 值而具有抗菌特性外，还充当革兰氏阴性细菌进入细胞膜的透化剂，并可能充当其他抗菌物质效果的增强剂。
The effect of lactic acid on the outer membrane permeability of Escherichia coli O157:H7, Pseudomonas aeruginosa, and Salmonella enterica serovar Typhimurium was studied utilizing a fluorescent-probe uptake assay and sensitization to bacteriolysis, For control purposes, similar assays were performed with EDTA (a permeabilizer acting by chelation) and with hydrochloric acid, the latter at pH values corresponding to those yielded by lactic acid, and also in the presence of KCN. Already 5 mM (pH 4.0) lactic acid caused prominent permeabilization in each species, the effect in the fluorescence assay being stronger than that of EDTA or HCl. Similar results were obtained in the presence of KCN, except for P. aeruginosa, for which an increase in the effect of HCl was observed in the presence of KCN, The permeabilization by lactic and hydrochloric acid was partly abolished by MgCl2. Lactic acid sensitized E. coli and serovar Typhimurium to the lytic action of sodium dodecyl sulfate (SDS) more efficiently than did HCl, whereas both acids sensitized P. aeruginosa to SDS and to Triton X-100. P. aeruginosa was effectively sensitized to lysozyme by lactic acid and by HCl. Considerable proportions of lipopolysaccharide were liberated from serovar Typhimurium by these acids; analysis of liberated material by electrophoresis and by fatty acid analysis showed that lactic acid was more active than EDTA or HCl in liberating lipopolysaccharide from the outer membrane. Thus, lactic acid, in addition to its antimicrobial property due to the lowering of the pH, also functions as a permeabilizer of the gram-negative bacterial enter membrane and may act as a potentiator of the effects of other antimicrobial substances.