Universidade Federal de Viçosa, Departamento de Veterinária, Campus UFV, Centro, 36570-900 Viçosa, MG, Brazil.
Universidade Federal de Viçosa, Departamento de Veterinária, Campus UFV, Centro, 36570-900 Viçosa, MG, Brazil.
Food Res Int. 2018 Mar;105:897-904. doi: 10.1016/j.foodres.2017.12.030. Epub 2017 Dec 13.
The use of nisin producers in foods is considered a mitigation strategy to control foodborne pathogens growth, such as Listeria monocytogenes, due to the production of this bacteriocin in situ. However, when the bacteriocin does not reach an adequate concentration, the target bacteria can develop a cross-response to different stress conditions in food, such as acid, thermal and osmotic. This study aimed to evaluate the interaction of a nisin-producing strain of Lactococcus lactis DY-13 and L. monocytogenes in BHI and skim milk, and its influence on general (sigB), acid (gadD2), thermal (groEL) and osmotic (gbu) stress-related genes of the pathogen. L. monocytogenes populations decreased approximately 2log in BHI and 1log in milk after 24h in co-culture with the nisin producer L. lactis, coherent with the increasing expression of nisK. Expression of stress-related genes by L. monocytogenes presented lower oscillation in BHI than in milk, indicating its better ability to survive in milk, despite the higher nisin production. Stress-related genes presented a varied expression by L. monocytogenes in the tested conditions: sigB expression remained stable or reduced over time; gadD2 presented high expression in milk; groEL presented low expression in BHI when compared to milk, trending to decrease overtime; gbu expression in milk after 24h was lower than in BHI. The presented study demonstrated the growth of a nisin producer L. lactis can affect the expression of stress-related genes by L. monocytogenes, and understating these mechanisms is crucial to enhance the conservation methods employed in foods.
在食品中使用乳链菌肽生产者被认为是控制食源性病原体生长的一种缓解策略，例如单核细胞增生李斯特菌，因为这种细菌素可以在原位产生。然而，当细菌素没有达到足够的浓度时，目标细菌可以对食品中的不同应激条件（如酸、热和渗透压）产生交叉反应。本研究旨在评估乳球菌 lactis DY-13 生产菌和单核细胞增生李斯特菌在 BHI 和脱脂乳中的相互作用，及其对病原体一般（sigB）、酸（gadD2）、热（groEL）和渗透（gbu）应激相关基因的影响。在与乳链菌肽生产者共培养 24 小时后，L. monocytogenes 在 BHI 和牛奶中的数量分别减少了约 2log 和 1log，这与 nisK 的表达增加一致。与在牛奶中相比，L. monocytogenes 在 BHI 中的应激相关基因表达波动较小，表明其在牛奶中具有更好的生存能力，尽管乳链菌肽的产量更高。在测试条件下，L. monocytogenes 的应激相关基因表达呈现出不同的表达模式：sigB 表达随时间保持稳定或减少；gadD2 在牛奶中表达较高；与牛奶相比，groEL 在 BHI 中的表达较低，且随时间呈下降趋势；24 小时后在牛奶中的 gbu 表达低于 BHI。本研究表明，乳链菌肽生产者的生长可以影响单核细胞增生李斯特菌应激相关基因的表达，了解这些机制对于增强食品中采用的保存方法至关重要。
