Background. Lactobacillus acidophilus is lactic acid bacteria that produce bacteriocins. Bacteriocins are antimicrobial peptides or proteins that exhibit activity against closely related bacteria. The aim of this study was to determine the effect of L. acidophilus ATCC 4356 bacteriocin against Staphylococcus aureus. Material and Methods. We used four different phenotypic methods for antimicrobial activities against two standard strains: methicillin-resistant S. aureus (MRSA) ATCC 33591 and methicillin-susceptible S. aureus (MSSA) ATCC 25923. The methods were (1) agar well diffusion, (2) overlay soft agar, (3) paper disk, and (4) modification of punch hole. The ammonium sulfate method was used to concentrate crude bacteriocin, and ultrafiltration and dialysis tubes were used to remove ammonium sulfate from the bacteriocins. Each method was repeated in triplicate. Result. L. acidophilus ATCC 4356 showed antimicrobial activity against both MRSA and MSSA standard strains only by the overlay soft agar method and not by the agar well diffusion, punch hole modification, and paper disk methods. No antimicrobial effects were observed in crude bacteriocins concentrated. Conclusion. The growth inhibition of S. aureus in overlay soft agar method may be due to the production of bacteriocin-like substances. The overlay soft agar method is a qualitative test, so there is a need for further study to optimize the conditions for the production of bacteriocin-like substances in the culture supernatant and precise comparison between the inhibitory activity and pheromone secretion of different strains.

中文翻译：

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嗜酸乳杆菌 ATCC 4356 细菌素对金黄色葡萄球菌的作用评价

背景。嗜酸乳杆菌是产生细菌素的乳酸菌。细菌素是具有对抗密切相关细菌活性的抗菌肽或蛋白质。本研究的目的是确定嗜酸乳杆菌ATCC 4356 细菌素对金黄色葡萄球菌的作用。材料与方法。我们使用四种不同的表型方法来检测两种标准菌株的抗菌活性：耐甲氧西林金黄色葡萄球菌(MRSA) ATCC 33591 和甲氧西林敏感金黄色葡萄球菌(MSSA) ATCC 25923。方法是 (1) 琼脂井扩散，(2 ）覆盖软琼脂，（3）纸盘，和（4）修改打孔。采用硫酸铵法浓缩粗制细菌素，并采用超滤和透析管去除细菌素中的硫酸铵。每种方法重复三次。结果。嗜酸乳杆菌ATCC 4356 仅通过覆盖软琼脂方法而非琼脂孔扩散、打孔修饰和纸盘方法显示出对 MRSA 和 MSSA 标准菌株的抗菌活性。在浓缩的粗细菌素中没有观察到抗菌作用。结论。覆盖软琼脂法中金黄色葡萄球菌的生长受到抑制可能是由于产生了类细菌素物质。覆盖软琼脂法属于定性试验，因此需要进一步研究优化培养上清液中类细菌素物质的产生条件以及不同菌株的抑制活性和信息素分泌的精确比较。