Photonic characteristics and ex vivo imaging of Escherichia coli-Xen14 within the bovine reproductive tract

Abstract 

The objectives of this study were to (1) characterize the photonic properties of Escherichia coli-Xen14 and (2) conduct photonic imaging of E. coli-Xen14 within bovine reproductive tract segments (RTS) ex vivo (Bos indicus). E. coli-Xen14 was grown for 24h in Luria Bertani medium (LB), with or without kanamycin (KAN). Every 24h, for an 8-d interval, inoculums were imaged and photonic emissions (PE) collected. Inoculums were subcultured and plated daily to determine the colony forming units (CFU) and ratio of photon emitters to nonemitters. In the second objective, abattoir-derived bovine reproductive tracts (n=9) were separated into posterior and anterior vagina, cervix, uterine body, and uterine horns. Two concentrations (3.2×10⁸ and 3.2×10⁶ CFU/200μL for relative [High] and [Low], respectively) of E. coli-Xen14 were placed in translucent tubes for detection of PE through RTS. The CFU did not differ (P=0.31) over time with or without KAN presence; they remained stable with 99.93% and 99.98% photon emitters, respectively. However, PE were lower (P<0.0001) in cultures containing KAN than in those containing no KAN (629.8±117.7 vs. 3012.0±423.5 relative lights units per second [RLU/sec], respectively). On average, the percentage of PE between RTS, for both concentrations, was higher (P<0.05) in the uterine body. In summary, E. coli-Xen14 remained stable with respect to the proportions of photon emitters with or without KAN (used to selectively culture E. coli-Xen14). However, KAN presence suppressed photonic activity. The ability to detect PE through various segments of the reproductive tract demonstrated the feasibility of monitoring the presence of E. coli-Xen14 in the bovine reproductive tract ex vivo.

Keywords: Biophotonics, Escherichia coli, Reproductive tract, Uterus