This study aimed to assess the safety aspects of 15 lactic acid bacteria (LAB) strains previously isolated from a dairy environment with relation to their beneficial features. LAB strains were assessed using phenotypic methods according to their production of virulence factors at 25 °C and 37 °C, as well as by examining their potential resistance to 15 antibiotics. Polymerase chain reaction (PCR) was also used to identify the presence of 50 genes associated with virulence factors and antibiotic resistance in the strains. None of the strains presented hemolytic activity or the production of gelatinase, lipase, deoxyribonuclease, or the tested biogenic amines. Based on the disk diffusion assay, all strains were resistant to oxacillin and sulfa/trimethoprim. Further, some were resistant to gentamicin (14), clindamycin (11), vancomycin (9), rifampicin (8), erythromycin (5), tetracycline (4), ampicillin (2), and chloramphenicol (1); no strain was resistant to imipenem. Regarding virulence- and antibiotic-resistance-related genes, 19 out of 50 tested genes were present in some strains; there was a variable association of expression. Based on the obtained data, the isolates presented relatively safe characteristics and behavior, findings that should lead to further studies to assess their potential usage as beneficial cultures in the food industry.

中文翻译：

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从乳制品系统中分离出的有益乳酸菌的安全概况

本研究旨在评估先前从乳品环境中分离出的 15 种乳酸菌 (LAB) 菌株的安全性及其有益特性。根据 LAB 菌株在 25 °C 和 37 °C 下毒力因子的产生，以及通过检查它们对 15 种抗生素的潜在抗性，使用表型方法对 LAB 菌株进行了评估。聚合酶链反应 (PCR) 还用于鉴定菌株中与毒力因子和抗生素抗性相关的 50 个基因的存在。没有菌株表现出溶血活性或产生明胶酶、脂肪酶、脱氧核糖核酸酶或测试的生物胺。根据圆片扩散试验，所有菌株都对苯唑西林和磺胺/甲氧苄啶有抗性。此外，一些对庆大霉素 (14)、克林霉素 (11)、万古霉素 (9)、利福平 (8)、红霉素 (5)、四环素 (4)、氨苄青霉素 (2) 和氯霉素 (1)；没有菌株对亚胺培南耐药。关于毒力和抗生素抗性相关基因，50 个测试基因中有 19 个存在于某些菌株中；有一个可变的表达关联。根据获得的数据，这些分离株表现出相对安全的特征和行为，这些发现应该导致进一步的研究，以评估它们在食品工业中作为有益培养物的潜在用途。