The increasing mandate for fresh-like food products and the possible hazards of chemically preserved foods necessitate the search for alternatives. Bacteriocins represent a promising food biopreservative. In the present study, one hundred enterococci isolates recovered from Egyptian raw cow milk and homemade dairy products were screened for bacteriocin production. The overall detection rate was 10%. Three isolates, namely, Enterococcus faecalis (OE-7 and OE-12) and Enterococcus hirae (OE-9), showed the highest antibacterial activity with narrow spectrum against multidrug-resistant (MDR) Gram-positive foodborne bacteria: Enterococcus faecalis and Staphylococcus aureus. The antimicrobial activity was completely abolished by trypsin and proteinase K but not affected by lipase and/or amylase indicating the protein nature of the antimicrobial activity. Optimum conditions for bacteriocin production were cultivation in MRS broth at 37 °C, pH 6-6.5 for 16-24 h. The tested bacteriocins exhibited bactericidal activity on S. aureus subsp. aureus ATCC 25923; such activity was further investigated by transmission electron microscopy that revealed leakage and lysis of treated cells. Characterization of tested bacteriocins revealed high activity in a wide range of pH and temperature, storage stability, and heat resistance. PCR analysis revealed that the tested isolates produced multiple enterocins showing homology with the enterocins L50A, AS-48, and 31. Finally, this study reported potent antibacterial activity of bacteriocins derived from dairy products Enterococci against MDR foodborne and spoilage pathogens. The potency, specificity, and stability of these bacteriocins presented promising perspectives for application as biopreservatives in the food industry. The biopreservation of foods by bacteriocins produced by lactic acid bacteria recovered directly from foods remains an innovative approach.

中文翻译：

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从埃及自制乳制品中回收的肠球菌分离株产生的细菌素对某些食源性病原体的抗菌活性。

像新鲜食品这样的食品要求越来越严格，以及化学腌制食品的潜在危害，因此必须寻找替代品。细菌素代表有前途的食品生物防腐剂。在本研究中，从埃及生牛奶和自制乳制品中回收的100株肠球菌被筛选出细菌素的产生。总体检测率为10％。三种分离株，即粪肠球菌（OE-7和OE-12）和平肠肠球菌（OE-9），对多药耐药（MDR）革兰氏阳性食源性细菌表现出最高的抗菌活性，且谱线较窄：粪肠球菌和葡萄球菌金黄色的。胰蛋白酶和蛋白酶K完全消除了抗微生物活性，但不受脂酶和/或淀粉酶的影响，表明抗微生物活性的蛋白质性质。细菌素生产的最佳条件是在MRS肉汤中于37°C，pH 6-6.5的条件下培养16-24小时。被测试的细菌素对金黄色葡萄球菌亚种具有杀菌活性。金黄色ATCC 25923; 通过透射电子显微镜进一步研究了这种活性，揭示了处理过的细胞的渗漏和裂解。被测细菌素的表征显示出在宽范围的pH和温度，储存稳定性和耐热性方面均具有高活性。PCR分析表明，测试的分离物产生了多种肠毒素，与肠毒素L50A，AS-48和31同源。最后，这项研究报道了源自乳球菌肠球菌的细菌素对食源性MDR和腐败病原体的有效抗菌活性。效力，特异性，这些细菌素的稳定性和稳定性为在食品工业中用作生物防腐剂提供了广阔的前景。直接从食品中回收的乳酸菌产生的细菌素对食品进行生物保存仍然是一种创新方法。