Costa Jean Carlos Correia Peres, Bolívar Araceli, Valero Antonio, Carrasco Elena, Zurera Gonzalo, Pérez-Rodríguez Fernando
Department of Food Science and Technology, Faculty of Veterinary, Agrifood Campus of International Excellence (ceiA3), University of Cordoba, 14014 Córdoba, Spain.
Department of Food Science and Technology, Faculty of Veterinary, Agrifood Campus of International Excellence (ceiA3), University of Cordoba, 14014 Córdoba, Spain.
Food Res Int. 2020 May;131:108928. doi: 10.1016/j.foodres.2019.108928. Epub 2019 Dec 23.
In this study, the inhibitory capacity of Lactobacillus sakei strain L115 against Listeria monocytogenes has been assayed at 4, 8, 11, 15 and 20 °C in broth culture. Besides, the use of predictive microbiology models for describing growth of both microorganisms in monoculture and coculture has been proposed. A preliminary inhibitory test confirmed the ability of Lb. sakei strain L115 to prevent the growth of a five-strain cocktail of L. monocytogenes. Next, the growth of microorganisms in isolation, i.e. in monoculture, was monitored and kinetic parameters maximum specific growth rate (μ) and maximum population density (N) were estimated by fitting the Baranyi model to recorded data. Inhibition coefficients (α) were calculated for the two kinetic parameters tested (μ and N) to quantify the percentage of reduction of growth when the microorganisms were in coculture in comparison with monoculture. The kinetic parameters were input into three interaction models, developed based on modifications of the Baranyi growth model, namely Jameson effect, new modified version of the Jameson effect and Lotka-Volterra models. Two approaches were utilized for simulation, one using the monoculture μ, under the hypothesis that the growth potential is similar under monoculture and coculture conditions provided the environmental conditions are not modified, and the other one, based on adjusting the monoculture kinetic parameter by applying the corresponding α to reproduce the observed μ under coculture conditions, assuming, in this approach, that the existence of a heterogeneous population can change the growth potential of each microbial population. It was observed that in coculture, μ of L. monocytogenes decreased (e.g., α = 31% at 4 °C) and the N was much lower than that of monoculture (e.g., α = 36% at 4 °C). The best simulation performance was achieved applying α to adjust the estimated monoculture growth rate, with the modified Jameson and Lotka-Volterra models showing better fit to the observed microbial interaction data as demonstrated by the fact that 100% data points fell within the acceptable simulation zone (±0.5 log CFU/mL from the simulated data). More research is needed to clarify the mechanisms of interaction between the microorganisms as well as the role of temperature.
在本研究中，已在肉汤培养中于4、8、11、15和20℃测定了清酒乳杆菌L115菌株对单核细胞增生李斯特菌的抑制能力。此外，还提出使用预测微生物学模型来描述两种微生物在单培养和共培养中的生长情况。初步抑制试验证实了清酒乳杆菌L115菌株具有阻止单核细胞增生李斯特菌五菌株混合物生长的能力。接下来，监测了微生物在分离状态下即单培养中的生长情况，并通过将巴拉尼模型拟合到记录数据来估计动力学参数最大比生长速率（μ）和最大种群密度（N）。针对所测试的两个动力学参数（μ和N）计算抑制系数（α），以量化微生物在共培养时与单培养相比生长减少的百分比。将动力学参数输入到基于巴拉尼生长模型修改而开发的三个相互作用模型中，即詹姆森效应、詹姆森效应的新修改版本和洛特卡 - 沃尔泰拉模型。采用了两种模拟方法，一种是在假设单培养和共培养条件下环境条件未改变时生长潜力相似的情况下，使用单培养的μ；另一种是在这种方法中，通过应用相应的α来调整单培养动力学参数以重现共培养条件下观察到的μ，假设异质种群的存在会改变每个微生物种群的生长潜力。观察到在共培养中，单核细胞增生李斯特菌的μ降低（例如，在4℃时α = 31%），并且N远低于单培养中的N（例如，在4℃时α = 36%）。通过应用α来调整估计的单培养生长速率可实现最佳模拟性能，修改后的詹姆森模型和洛特卡 - 沃尔泰拉模型对观察到的微生物相互作用数据显示出更好的拟合，这一事实表明100%的数据点落在可接受的模拟区域内（与模拟数据相差±0.5 log CFU/mL）。需要更多研究来阐明微生物之间的相互作用机制以及温度的作用。
