Effects of Environmental Chemical Pollutants on Bacterial Growth Dynamics: Implications for Microbial Health and Disease Ecology

Chemical pollutants released from agricultural, industrial, and domestic sources increasingly compromise microbial communities that sustain ecosystem functioning, soil fertility, and biogeochemical cycling. These environmental contaminants can alter bacterial growth dynamics, leading to reduced microbial diversity, impaired ecological balance, and potential implications for environmental and public health. This study aimed to examine the impact of chemical pollutants on bacterial growth dynamics through a secondary analysis of OD600 time-series measurements of bacterial cultures exposed to selected pesticide and biocide compounds. This quantitative secondary data analysis was conducted using a publicly available dataset titled "Bacterial bioindicators growth curves" (DOI: 10.6084/m9.figshare.28684982), originally published by Tom Smith in 2025 on the Figshare repository. Data on bacterial isolates and synthetic communities were obtained from two primary files capturing hourly OD600 readings under exposure to four chemical pollutants—thiabendazole, propiconazole, novaluron, and bifenthrin—with dimethyl sulfoxide (DMSO) as the control. Descriptive statistics, growth-kinetic modelling, treatment-versus-control comparisons, and phase-resolved analyses were performed using Python (pandas, NumPy, SciPy) and Microsoft Excel. A total of 307 OD600 measurements across 61 timepoints (0–71 hours) and six wells were analysed. Descriptive findings revealed comparable mean OD600 values across thiabendazole (0.1832 ± 0.0720), propiconazole (0.2078 ± 0.0867), novaluron (0.2154 ± 0.0960), and DMSO (0.1879 ± 0.0721), while bifenthrin showed a markedly lower mean (0.0445 ± 0.0007). Growth-kinetic analysis indicated near-identical maximum specific growth rates (μmax ≈ 0.24 h⁻¹) for thiabendazole, propiconazole, and novaluron, with novaluron showing the highest peak optical density (ODmax = 0.4130) and area under the curve (AUC = 15.15 OD·h). Bifenthrin produced strong inhibition (ODmax −86.0% versus control), whereas propiconazole and novaluron stimulated bacterial growth (+15.8% and +28.3%, respectively). Phase-resolved analysis confirmed compound-specific shifts in stationary and decline-phase OD values relative to DMSO. Chemical pollutants exert compound-specific effects on bacterial growth dynamics, ranging from strong inhibition (bifenthrin) to mild stimulation (novaluron, propiconazole). Integrating microbial growth-curve assessment with environmental monitoring frameworks may improve early detection of pollutant-driven ecological disturbance and inform safer regulatory thresholds for soil and aquatic ecosystems.