GLUCOSE-ENHANCED PHOSPHATE BIOMINERALIZATION BY ESCHERICHIA COLI IN A SYNTHETIC URINE

Escherichia coli is widely considered a model organism and has been studied in a variety of settings. Phosphate mineralization by E. coli has been previously studied, but only under certain limited conditions. Urine is super saturated with respect to phosphate minerals such as struvite and hydroxyapatite, but phosphate precipitation by E. coli in urine, particularly from a mineralogical standpoint, remains under-characterized. As E. coli are commonly found in the human urinary tract and are often associated with the formation of pathological phosphatic kidney stones, understanding how they can produce phosphate minerals in urine is of particular importance. Moreover, individuals with diabetes, who often have higher levels of glucose in their urine, experience kidney stones at significantly higher frequencies. This study aims to evaluate the mineralization processes of E. coli and the enhancement of phosphate removal in the presence of glucose.

In order to characterize these processes, isolated strains of E. coli were inoculated into synthetic urine solutions in the presence and absence of added glucose. The experiment was run over the course of five days, and aqueous samples were taken regularly throughout the experiment for additional analysis. The pH of these samples was recorded, and bulk chemical analysis was conducted using an Inductively Coupled Plasma Atomic Emissions Spectrometer (ICP-AES). Following the culmination of the experiment, solutions were centrifuged in order to collect mineral precipitate and biomass. These solids were rinsed and prepared for Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. Notably, the solutions enhanced with glucose produced significantly more precipitate than those without. As such, the solutions without glucose did not produce enough recoverable precipitate to be analyzed by FTIR. Cell density measurements following the experiment show that glucose stimulated cell growth and reproduction, thereby enhancing phosphate removal.