<p>Dynamic association of Dr⁺ <i>E. coli</i> with calcium oxalate crystals in artificial urine.</p>

Overnight cultures were diluted in AU to OD₆₀₀ = 0.025, supplemented with CaOx to a final concentration of 0.05% (w/v), and incubated under static conditions at 37 °C. The video shows four independent biological experiments recorded after 2 h of incubation.

Images were acquired for 10 s at 0.1 s intervals using phase-contrast microscopy. Bacteria display characteristic polar attachment to CaOx crystals, forming radial arrangements around crystal surfaces. Collective bacterial motility results in visible oscillations and occasional displacement of crystals along the bottom surface.