Ben Farhat Leila, Romeo Flora Valeria, Foti Paola, Russo Nunziatina, Randazzo Cinzia Lucia, Caggia Cinzia, Abidi Ferid
Laboratory of Protein Engineering and Bioactive Molecules (LR11ES24), INSAT (Institut National des Sciences Appliquées et de Technologie Centre Urbain Nord), University of Carthage, Tunis BP 676-1080, Tunisia.
Department of Agriculture, Food and Environment (Di3A), University of Catania, Via S. Sofia 100, 95123 Catania, Italy.
Microorganisms. 2022 Sep 20;10(10):1876. doi: 10.3390/microorganisms10101876.
This study aimed to evaluate the antimicrobial activity of both cells, and cell-free supernatants (CFS) of 7 selected lactic acid bacteria (LAB) strains belonging to (4 strains), (1 strain), (1 strain), and (1 strain) species, against , Typhimurium, and , by both the agar-well diffusion and co-culture methods. In addition, probiotic and safety traits were also detected. Great variability was detected on antimicrobial effects, whereas all tested strains were found sensitive to most of the tested antibiotics, and without any DNase, gelatinase, or hemolytic activity. Moreover, strains showed excellent survival in acidic conditions and exhibited tolerance to pepsin and bile salts. Based on the in vitro results, the CFSs of two selected strains were applied, in a mixed solution, as bio-preservative into minimally processed pomegranate arils, inoculated with a cocktail of and . Samples, packaged in an ordinary atmosphere, were analyzed during refrigerated storage, for up to 12 days, for physicochemical (as weight loss, texture, color, pH, total soluble solids and organic acid content) and for microbiological traits. Results revealed the effectiveness of CFS, up to 12 days, in reducing weight loss and microbial growth, without any significant effect on texture, total soluble solid content and color, found comparable to the acid citric treatment, highlighting the multi-functional potential of selected probiotic strains.
本研究旨在通过琼脂孔扩散法和共培养法，评估7株选定的乳酸菌（LAB）菌株的细胞及其无细胞上清液（CFS）对大肠杆菌、鼠伤寒沙门氏菌、金黄色葡萄球菌和单核细胞增生李斯特菌的抗菌活性。此外，还检测了益生菌特性和安全性。抗菌效果存在很大差异，而所有测试菌株对大多数测试抗生素敏感，且无任何脱氧核糖核酸酶、明胶酶或溶血活性。此外，菌株在酸性条件下表现出良好的存活率，并对胃蛋白酶和胆盐具有耐受性。基于体外实验结果，将两种选定乳酸菌菌株的无细胞上清液以混合溶液的形式作为生物防腐剂应用于接种了大肠杆菌和单核细胞增生李斯特菌混合菌液的轻度加工石榴籽中。将包装在普通大气中的样品在冷藏储存期间进行长达12天的分析，检测其理化特性（如重量损失、质地、颜色、pH值、总可溶性固形物和有机酸含量）和微生物特性。结果表明，无细胞上清液在长达12天的时间内有效地减少了重量损失和微生物生长，对质地、总可溶性固形物含量和颜色没有任何显著影响，与柠檬酸处理相当，突出了选定益生菌菌株的多功能潜力。
