Department of Physics, University of Arkansas, Fayetteville, AR, United States of America.
Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, United States of America.
PLoS One. 2021 Jan 12;16(1):e0245205. doi: 10.1371/journal.pone.0245205. eCollection 2021.
Growth curve measurements are commonly used in microbiology, while the use of microplate readers for such measurements provides better temporal resolution and higher throughput. However, evaluating bacterial growth with microplate readers has been hurdled by barriers such as multiple scattering. Here, we report our development of a method based on the time derivatives of the optical density (OD) and/or fluorescence (FL) of bacterial cultures to overcome these barriers. First, we illustrated our method using quantitative models and numerical simulations, which predicted the number of bacteria and the number of fluorescent proteins in time as well as their time derivatives. Then, we systematically investigated how the time derivatives depend on the parameters in the models/simulations, providing a framework for understanding the FL growth curves. In addition, as a demonstration, we applied our method to study the lag time elongation of bacteria subjected to treatment with silver (Ag+) ions and found that the results from our method corroborated well with that from growth curve fitting by the Gompertz model that has been commonly used in the literature. Furthermore, this method was applied to the growth of bacteria in the presence of silver nanoparticles (AgNPs) at various concentrations, where the OD curve measurements failed. We showed that our method allowed us to successfully extract the growth behavior of the bacteria from the FL measurements and understand how the growth was affected by the AgNPs.
生长曲线测量在微生物学中很常见，而使用微孔板读数器进行此类测量可以提供更好的时间分辨率和更高的通量。然而，使用微孔板读数器评估细菌生长受到了多重散射等障碍的阻碍。在这里，我们报告了一种基于细菌培养物的光密度（OD）和/或荧光（FL）时间导数的方法的发展，以克服这些障碍。首先，我们使用定量模型和数值模拟来说明我们的方法，这些模型和模拟预测了细菌数量和荧光蛋白数量随时间以及它们的时间导数的变化。然后，我们系统地研究了时间导数如何依赖于模型/模拟中的参数，为理解 FL 生长曲线提供了一个框架。此外，作为一个演示，我们应用我们的方法来研究细菌受到银（Ag+）离子处理时的延迟时间延长，发现我们的方法的结果与文献中常用的 Gompertz 模型拟合生长曲线的结果非常吻合。此外，该方法还应用于不同浓度的银纳米颗粒（AgNPs）存在下的细菌生长，在这种情况下，OD 曲线测量失败了。我们表明，我们的方法允许我们从 FL 测量中成功提取细菌的生长行为，并了解 AgNPs 如何影响生长。
