酱鸭中优势背景菌群对金黄色葡萄球菌生长影响的预测模拟

Predictive Modeling of the Effect of Dominant Background Microflora on the Growth of Staphylococcus aureus in Sauced Duck

为研究酱鸭中优势背景菌群对金黄色葡萄球菌生长的影响,构建和验证相关生长预测模型,将金黄色葡萄球菌单独接种或与优势背景菌群混合接种至已灭菌的酱鸭样品中,置于不同恒定温度(10,12,16,20,25,30℃)条件下培养,开展非竞争和竞争生长试验。采用一步法分析非竞争生长和竞争生长数据,同步构建初级模型(非竞争生长模型和竞争生长模型)和二级模型,并通过另设的恒定温度生长试验对模型进行验证。结果表明,一步法适用于酱鸭中金黄色葡萄球菌与背景菌群的生长分析,模型估计的非竞争状态下金黄色葡萄球菌的最低生长温度为9.28℃,最大生长浓度为9.39 lg(CFU/g)。与非竞争生长相比,竞争状态下金黄色葡萄球菌的迟滞期略长,最大比生长速率无显著差异;然而,当背景菌群的生长进入稳定期后,金黄色葡萄球菌的生长速率显著降低,表现出抑制效应(α=0.556),模型估计的金黄色葡萄球菌的最低生长温度为9.40℃,背景菌群的最大生长浓度为9.93 lg(CFU/g)。验证试验表明:构建的模型能准确描述酱鸭中金黄色葡萄球菌及背景菌群的生长。本研究结果可为酱鸭中金黄色葡萄球菌的定量风险评估和货架期预测提供参考。

The objective of this study was to investigate the effect of dominant background microflora(BM) on the growth of Staphylococcus aureus in sauced duck, and then to develop and validate the predictive models. Non-competitive and competitive growth experiments of Staphylococcus aureus under 10, 12, 16, 20, 25, 30 ℃ were conducted respectively by inoculating Staphylococcus aureus alone or mixed with BM into the sterile sauced duck samples. Growth data under non-competitive or competitive experiments was used to directly construct both primary model(non-competitive growth model and competitive growth model) and secondary model through one-step kinetic analysis, and growth experiments from newly designed constant temperature conditions were chosen for model validation. The results showed that one-step approach can be used to predict the growth of Staphylococcus aureus and BM in sauced duck. Under non-competitive conditions, the estimated minimum growth temperature and maximum growth density of Staphylococcus aureus were 9.28 ℃ and 9.39 lg(CFU/g), respectively. The lag period of Staphylococcus aureus under competitive growth was slightly longer than those under non-competitive conditions, while there was no significant difference on the maximum specific growth rate. However, the growth rate of Staphylococcus aureus decreased significantly after the growth of BM entered into the stationary phase, indicating the inhibitory effect of BM on the growth Staphylococcus aureus (α = 0.556).And the estimated minimum growth temperature of Staphylococcus aureus was 9.40 ℃, and the maximum growth density of BM was 9.93 lg(CFU/g). Validation tests showed that the models could accurately describe the growth of Staphylococcus aureus and BM in sauced duck. The results of this study can provide scientific basis for quantitative risk assessment of Staphylococcus aureus in sauce duck and predict its shelf life.