This study aimed to evaluate the effect of Lactobacillus rhamnosus GG on growth of Staphylococcus aureus and Listeria monocytogenes, inoculated alone or in combination on surface of Minas Frescal cheeses, during storage for 21 days at 7 °C. Survival percentages of each individual bacterial species after exposure to in vitro simulated gastrointestinal conditions (SGC) were also determined. The addition of L. rhamnosus did not affect (P > 0.05) pH, moisture, fat, protein and texture profile of Minas Frescal cheeses. L. rhamnosus was able to survive in suitable counts (>6 Log CFU/g) in cheeses from the 7th day of storage, with high survival (>74.6–86.4%) after SGC. An inhibitory effect of L. rhamnosus on L. monocytogenes was observed in cheeses (decrease of 1.1–1.6 Log CFU/g) and after SGC (20% reduction in the survival). No inhibitory effect of L. rhamnosus was observed on S. aureus counts (P > 0.05), and this microorganism did not survive the exposure to SGC. In conclusion, the addition of L. rhamnosus in Minas Frescal cheese has a potential for L. monocytogenes inhibition. Further studies are necessary to elucidate the mechanisms involved in the inhibition process and determine the survival ability of the bacterial species evaluated in in vivo experiments.

本研究旨在评估鼠李糖乳杆菌GG对米纳斯弗雷斯卡尔奶酪表面单独或组合接种的金黄色葡萄球菌和单核细胞增生李斯特菌生长的影响，在7°C下储存21天。还确定了暴露于体外模拟胃肠道条件（SGC）后每种细菌个体的存活百分比。鼠李糖乳杆菌的添加不会影响 Minas Frescal奶酪的（P > 0.05）pH，水分，脂肪，蛋白质和质地。鼠李糖乳杆菌从储存的第7天起，奶酪能够以合适的数量（> 6 Log CFU / g）存活，而SGC后的存活率很高（> 74.6–86.4％）。在奶酪中和SGC后，鼠李糖乳杆菌对单核细胞增生李斯特菌均有抑制作用（降低1.1–1.6 Log CFU / g），而SGC则抑制了鼠李糖乳杆菌（存活率降低20％）。没有观察到鼠李糖乳杆菌对金黄色葡萄球菌计数具有抑制作用（P  > 0.05），并且该微生物在暴露于SGC后仍不能幸免。总之，在米纳斯弗雷斯卡尔奶酪中添加鼠李糖乳杆菌可能会导致单核细胞增生李斯特菌抑制。需要进一步的研究来阐明抑制过程所涉及的机制，并确定体内实验中评估的细菌物种的生存能力。