Department of Bioconvergence Science and Technology, College of Agriculture and Life Science, Kangwon National University, Chunchon, South Korea; Department of Chemistry and Agricultural Industries, Faculty of Agronomy, University of Kinshasa, Kinshasa, Democratic Republic of the Congo.
BioTeC, Chemical and Biochemical Process Technology and Control, Department of Chemical Engineering, KU Leuven, Ghent, Belgium.
Food Microbiol. 2018 Dec;76:287-295. doi: 10.1016/j.fm.2018.06.006. Epub 2018 Jun 14.
In this work, the effect of environmental factors on Staphylococcus aureus (ATCC 13150) biofilm formation in tryptic soy broth was investigated under different ranges of pH (3.0-9.5), ethanol concentration (EtOH 0.0-20.0%), and a (NaCl, 0.866-0.992). Biofilm formation was quantified using the crystal violet staining method and optical density (OD: 590 nm) measurements. Biofilm formation was significantly stronger at pH and a close to S. aureus optimal growth conditions, while it was high at EtOH around 2.5-3.5%. Data sets from the difference between the OD measurements of the test and control (ΔOD) were fitted to the cardinal parameter model (CPM) and cardinal parameter model with inflection (CPMI) to describe the effect of the environmental factors. The models showed good quality of fit for the experimental data in terms of calculated RMSE, with the latter ranging from 0.276 to 0.455. CPM gave a good quality of fit compared to CPMI for the environmental factors tested. Optimal pH was close to neutral (6.76-6.81) and biofilm formation was possible till pH = 3.81-3.78 for CPM and CPMI, respectively. Optimum EtOH and a conditions for biofilm formation were in the range of 1.99-2.75 and 0.98-0.97, respectively. Predicted OD values observed using strain 13150 were very closely correlated to the OD values predicted with strain 12600 with R of 0.978, 0.991, and 0.947 for pH, EtOH, and a, respectively. The cultivable bacterial cells within the biofilm were enumerated using standard plate counting and a linear model was applied to correlate the attached biofilm cells to ΔOD of biofilm formation. It was found that the biofilm formation correlated with S. aureus population growth. At 2.5-3.5% of EtOH the maximum population density was lower than that observed at 0.0% of EtOH. As 2.5-3.5% of EtOH initiated a stronger biofilm formation, biofilm formation seems to be induced by ethanol stress. The development of cardinal parameter models to describe the effect environmental factors of importance to biofilm formation, offers a promising predictive microbiology approach to decrypting the S. aureus population growth and survival ability on food processing surfaces.
在这项工作中，研究了不同 pH 值（3.0-9.5）、乙醇浓度（EtOH 0.0-20.0%）和 a（NaCl，0.866-0.992）范围内环境因素对金黄色葡萄球菌（ATCC 13150）在胰蛋白酶大豆肉汤中生物膜形成的影响。使用结晶紫染色法和光密度（OD：590nm）测量来定量生物膜形成。在接近金黄色葡萄球菌最佳生长条件的 pH 和 a 时，生物膜形成明显较强，而在 EtOH 约为 2.5-3.5%时生物膜形成较高。从测试和对照（ΔOD）的 OD 测量值之间的差异数据集中，使用基数参数模型（CPM）和具有拐点的基数参数模型（CPMI）来描述环境因素的影响。就计算的 RMSE 而言，模型对实验数据的拟合质量较好，后者范围在 0.276 到 0.455 之间。与 CPMI 相比，CPM 对测试的环境因素具有较好的拟合质量。最佳 pH 值接近中性（6.76-6.81），CPM 和 CPMI 的生物膜形成分别可在 pH=3.81-3.78 时进行。生物膜形成的最佳 EtOH 和 a 条件分别在 1.99-2.75 和 0.98-0.97 范围内。使用菌株 13150 观察到的预测 OD 值与使用菌株 12600 预测的 OD 值非常相关，相关性分别为 0.978、0.991 和 0.947。使用标准平板计数法对生物膜内可培养细菌细胞进行计数，并应用线性模型将附着的生物膜细胞与生物膜形成的 OD 值相关联。结果发现，生物膜形成与金黄色葡萄球菌种群生长有关。在 2.5-3.5%的 EtOH 下，最大种群密度低于在 0.0%EtOH 下观察到的密度。由于 2.5-3.5%的 EtOH 引发了更强的生物膜形成，因此生物膜形成似乎是由乙醇胁迫引起的。开发基数参数模型来描述对生物膜形成有重要影响的环境因素，为解密金黄色葡萄球菌在食品加工表面的种群生长和生存能力提供了一种很有前途的预测微生物学方法。
