van Schaik W, Gahan C G, Hill C
Department of Microbiology and National Food Biotechnology Centre, University College, Cork, Ireland.
J Food Prot. 1999 May;62(5):536-9. doi: 10.4315/0362-028x-62.5.536.
Log-phase Listeria monocytogenes cells become tolerant to a variety of environmental stresses following acid adaptation at pH 5.5. We demonstrated that adapted cells also exhibit increased tolerance to nisin and, to a lesser extent, lacticin 3147. At nisin concentrations of 100 and 200 IU/ml the survival of acid-adapted cells was approximately 10-fold greater than nonadapted cells. However, acid adaptation had only a moderate effect on the tolerance of L. monocytogenes to lacticin 3147, a phenomenon that possibly reflects the distinct mode of action of this bacteriocin. Analysis of the fatty acid composition of the bacterial membrane indicated that straight-chain fatty acids C14:0 and C16:0 were significantly increased in acid-adapted cells while levels of C18:0 decreased. The results indicate that stress mechanisms that are induced in mildly acidic conditions provide protection against the antimicrobial action of bacteriocins. This increased resistance of acid-adapted L. monocytogenes could cause increased survival of this pathogen in food products in which nisin or other bacteriocins are used as preservatives.
对数期的单核细胞增生李斯特菌细胞在pH 5.5条件下进行酸适应性处理后，对多种环境压力产生耐受性。我们证明，经过适应性处理的细胞对乳链菌肽以及程度稍低的乳酸链球菌素3147也表现出更高的耐受性。在乳链菌肽浓度为100和200 IU/ml时，酸适应性细胞的存活率比未适应细胞高出约10倍。然而，酸适应性处理对单核细胞增生李斯特菌对乳酸链球菌素3147的耐受性只有中等程度的影响，这一现象可能反映了这种细菌素独特的作用方式。对细菌细胞膜脂肪酸组成的分析表明，酸适应性细胞中直链脂肪酸C14:0和C16:0显著增加，而C18:0的水平下降。结果表明，在轻度酸性条件下诱导产生的应激机制可提供针对细菌素抗菌作用的保护。酸适应性单核细胞增生李斯特菌这种增强的抗性可能会导致该病原体在使用乳链菌肽或其他细菌素作为防腐剂的食品中存活率增加。
