Effect of metabolites on the survival and biofilm formation of Pantoea piersonii (Basionym: Kalamiella piersonii) in synthetic urine media.

Pantoea piersonii (Basionym: Kalamiella piersonii) is an opportunistic pathogen capable of forming strong biofilms and infecting diverse anatomical sites. In this study, we investigated the growth, biofilm forming ability and ureolytic activity of P. piersonii under different growth conditions using synthetic urine to test its adaptability under different urinary conditions. We used P. piersonii strain YU22, isolated from the urine of a patient with kidney stone disease, and cultured under different urea concentrations (10 mM − 420 mM) to evaluate urea tolerance. Glucose, creatinine, and albumin were supplemented in synthetic urine to simulate the glycosuria, creatinuria, and albuminuria. Additionally, the effect of urinary pH variation was examined by adjusting the media to pH 5, pH 7, and pH 8. To investigate the ability of P. piersonii to co-exist with other key uropathogenic bacteria, we used a uropathogenic Escherichia coli, in a co-culture experiment. Under all the tested conditions, the growth, biofilm formation, and ureolytic activity were quantified using standard methods. Expression of urea carboxylase and allophanate hydrolase, in the selected conditions was analyzed using qRT-PCR. P. piersonii was able to tolerate urea at all the tested concentrations, showing a significant increase in growth (OD600) with increasing concentrations of urea from 0.19 ± 0.01 (10 mM) to 0.59 ± 0.01 (420 mM) (p < 0.01). Biofilm formation measured by crystal violet staining method also showed significant increase with OD590 values from 10 mM (0.55 ± 0.03) to 420 mM urea (1.74 ± 0.05) (p < 0.01). Among the nutritional supplements the highest growth and biofilm formation was observed in glucose, followed by creatinine and albumin. The combination of glucose with creatinine resulted in 25% and 30% increase in growth, respectively, compared to media containing glucose or creatinine separately. pH 7 favored growth and biofilm formation in all the tested conditions, except in the presence of glucose. Growth response and ureolytic activity varied significantly with changes in the nutritional composition and pH of the media (p < 0.05). In dual-species biofilm environment, P. piersonii dominated over E. coli under the tested growth conditions, suggesting a competitive advantage in the urinary environment that may influence community structure in mixed-species biofilms. These results demonstrate that the survival mechanism and ureolytic activity of P. piersonii are complex with the ability to adapt to varying environmental conditions in response to nutrient availability to enable survival under extreme conditions. However, these preliminary findings require validation through further investigations.