Growth kinetics modeling of Pseudomonas aeruginosa in natural mineral water.

Abstract

The study investigates the growth kinetics of Pseudomonas aeruginosa, a foodborne pathogen, in natural mineral water (NMW), assessing the impact of temperature from bottling to consumption. A pool of four P. aeruginosa strains isolated from NMW was inoculated (~102 CFU/mL) into two bottled water batches, with Batch 2 having higher initial heterotrophic bacterial counts. Samples were stored at 7, 12, 20, 25, and 37 °C, and populations of P. aeruginosa and heterotrophic bacteria were enumerated over time. P. aeruginosa survived, but did not grow, at 7 °C for at least 102 days, while substantial growth occurred at higher temperatures. Fitting the Baranyi model showed that, between 12 and 37 °C, lag phase duration ranged from 100.6 to 4.6 h, and maximum growth rate varied from 0.017 to 0.405 h-1, with no significant batch effect. Maximum population ranged from 4 to 5 log CFU/mL, with lower values in Batch 2, likely due to microbial competition. Temperature effects on kinetics were adequately described using the Ratkowsky square-root model with Bayesian inference, allowing incorporation of variability. P. aeruginosa strains showed strong survival capacity under nutrient-limited conditions, such as NMW. Thus, using the generated models, the risks associated with this opportunistic pathogen in NMW consumption will be able to be estimated. While lowering temperature effectively limits microbial growth, it is impractical across the bottled NMW production chain. Therefore, ensuring safety requires preventing raw water contamination through strict hygiene practices at all stages, from source water extraction to bottling and distribution.