Murdock C A, Cleveland J, Matthews K R, Chikindas M L
Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901-8520, USA.
Lett Appl Microbiol. 2007 Mar;44(3):255-61. doi: 10.1111/j.1472-765X.2006.02076.x.
The goal of this study was to determine whether nisin and lactoferrin would act synergistically to inhibit the growth of Listeria monocytogenes and Escherichia coli O157:H7.
Lactoferrin and nisin separately or in combination were suspended in peptone yeast glucose broth and following inoculation with L. monocytogenes or E. coli O157:H7 growth inhibition of each pathogen was determined. At 1000 microg ml(-1) lactoferrin L. monocytogenes was effectively inhibited. However, E. coli O157:H7 initially was inhibited and then grew to cell density similar to the control. A combination of 500 microg ml(-1) of lactoferrin and 250 IU ml(-1) of nisin effectively inhibited the growth of E. coli O157:H7, whereas, 250 microg ml(-1) of lactoferrin and 10 IU ml(-1) of nisin were inhibitory to L. monocytogenes.
The results suggest that lactoferrin and nisin act synergistically to inhibit the growth of L. monocytogenes and E. coli O157:H7.
Natural preservatives that are active against gram-positive and gram-negative pathogens are desirable to the food industry and consumers. This study demonstrates that lactoferrin and nisin work synergistically reducing the levels required independently inhibiting growth of two major foodborne pathogens. Previous reported results indicated a low level of antimicrobial activity; however, this work was not performed in low divalent cation concentration media. It has been suggested that nondivalent cation-limiting medium such as trypticase soy broth (TSB), can reduce or completely eliminate the inhibitory activity. Further knowledge of these interactions can increase the understanding of the antimicrobial activity of lactoferrin. This should make the use of these compounds by industry more attractive.
本研究的目的是确定乳酸链球菌素和乳铁蛋白是否会协同作用以抑制单核细胞增生李斯特菌和大肠杆菌O157:H7的生长。
将乳铁蛋白和乳酸链球菌素单独或联合悬浮于蛋白胨酵母葡萄糖肉汤中，接种单核细胞增生李斯特菌或大肠杆菌O157:H7后，测定每种病原体的生长抑制情况。在1000微克/毫升乳铁蛋白浓度下，单核细胞增生李斯特菌受到有效抑制。然而，大肠杆菌O157:H7最初受到抑制，随后生长至与对照相似的细胞密度。500微克/毫升乳铁蛋白和250国际单位/毫升乳酸链球菌素的组合有效抑制了大肠杆菌O157:H7的生长，而250微克/毫升乳铁蛋白和10国际单位/毫升乳酸链球菌素对单核细胞增生李斯特菌具有抑制作用。
结果表明乳铁蛋白和乳酸链球菌素协同作用可抑制单核细胞增生李斯特菌和大肠杆菌O157:H7的生长。
对食品工业和消费者而言，对革兰氏阳性和革兰氏阴性病原体均有活性的天然防腐剂是理想的。本研究表明，乳铁蛋白和乳酸链球菌素协同作用，降低了独立抑制两种主要食源性病原体生长所需的水平。先前报道的结果显示抗菌活性较低；然而，这项工作并非在低二价阳离子浓度的培养基中进行。有人提出，诸如胰蛋白酶大豆肉汤（TSB）等非二价阳离子限制培养基可降低或完全消除抑制活性。对这些相互作用的进一步了解可增进对乳铁蛋白抗菌活性的认识。这应会使工业界对这些化合物的使用更具吸引力。
