Cyanobacterial crowding-out effects on metabolite partitioning: Modeling 2-methylisoborneol (MIB) release dynamics and implications

2-Methylisoborneol (MIB), a potent cyanobacterial metabolite, impairs drinking water quality through taste-and-odor issues at trace concentrations. Despite its significant impact, the intracellular dynamics and environmental release mechanisms of MIB remain poorly characterized. We developed a mechanistic model of growth-phase dependent MIB release through controlled experiments with two producer strains. The model reveals that the extracellular MIB proportion (f=e_MIB/t_MIB) follows a consistent pattern: decreasing to a minimum at mid-log phase before rising and stabilizing (f: 0.4–0.6) during stationary phase, suggesting crowding-induced cell lysis drives release dynamics. Application of the model to Lake Taihu successfully reconstructed two odor events during 2022–2023, elucidating both the spatiotemporal development of MIB producers and identifying critical risk thresholds at ∼15°C and > 30°C under moderate light (0.1–0.4 mol m⁻² d⁻¹) - patterns undetectable by conventional monitoring. Our findings demonstrate that physiological transitions, rather than just biomass accumulation, control odorant release. This framework may extend to other algal metabolites (e.g., geosmin, cyanotoxins), offering broader predictive capability. By linking cellular processes to water quality risks, our approach enables proactive management of cyanobacterial contaminants, informing both early warning systems and operational guidance for oxidant-type optimization to prevent large-scale release of hazardous compounds from algal cells.