Department of Molecular Biology, University of León, 24071 León, Spain.
J Dairy Sci. 2013 Aug;96(8):4912-20. doi: 10.3168/jds.2013-6643. Epub 2013 Jun 13.
This study investigated the antimicrobial activity of 3 natural (thymol, carvacrol, and gallic acid) and 2 synthetic [butylated hydroxyanisole (BHA) and octyl gallate] phenolic compounds, individually and in binary combinations, on 4 dairy isolates of Enterococcus faecalis with different virulence factors (β-hemolytic, gelatinase, or trypsin activities; acquired resistance to erythromycin or tetracycline; and natural resistance to gentamicin). A checkerboard technique and a microdilution standardized method were used. All compounds individually tested exhibited antimicrobial activity against E. faecalis, with minimal inhibitory concentrations (MIC) ranging from 30 μg/mL (octyl gallate) to 3,150 μg/mL (gallic acid), although no significant differences were detected among strains to each phenolic compound. Carvacrol in combination with thymol or gallic acid, and gallic acid combined with octyl gallate showed partial synergistic inhibition of all E. faecalis strains. The most effective combinations were thymol+carvacrol and gallic acid+octyl gallate, as the MIC for each of these compounds was reduced by 67 to 75% compared with their respective individual MIC. These results highlight the possibility of using combinations of these phenolic compounds to inhibit the growth of potential virulent or spoilage E. faecalis strains by reducing the total amount of additives used in dairy foods.
本研究调查了 3 种天然（百里香酚、香芹酚和没食子酸）和 2 种合成酚类化合物（丁基羟基茴香醚（BHA）和辛基 gallate）单独以及二元组合对具有不同毒力因子（β-溶血、明胶酶或胰蛋白酶活性；获得对红霉素或四环素的抗性；以及对庆大霉素的天然抗性）的 4 种乳品分离的粪肠球菌的抗菌活性。使用棋盘技术和微稀释标准化方法进行测试。所有单独测试的化合物均表现出对粪肠球菌的抗菌活性，最小抑菌浓度（MIC）范围为 30 μg/mL（辛基 gallate）至 3150 μg/mL（没食子酸），尽管对每种酚类化合物的菌株之间未检测到显着差异。香芹酚与百里香酚或没食子酸联合，以及没食子酸与辛基 gallate 联合显示出对所有粪肠球菌菌株的部分协同抑制作用。最有效的组合是百里香酚+香芹酚和没食子酸+辛基 gallate，因为与各自的单独 MIC 相比，这些化合物的 MIC 降低了 67%至 75%。这些结果强调了使用这些酚类化合物的组合来抑制潜在的致病或腐败粪肠球菌菌株生长的可能性，从而减少乳制品中添加剂的总用量。
