ONLINE DETECTION OF BACTERIAL ADHESION IN A SHEAR GRADIENT WITH BIOLUMINESCENCE BY A PSEUDOMONAS-FLUORESCENS (LUX) STRAIN

On-line detection of bacterial adhesion in a shear flow gradient was measured with an engineered bioluminescent bacterium. Parallel plate flow cells showed colonization by a Pseudomonas fluorescens strain containing the Vibrio fisheri (lux) bioluminescent operon. When induced by sodium salicylate, bulk phase and sessile cells were assayed quantitatively with an ammeter-photomultiplier-fiber optic system. The detection limit in a shear force gradient was 2 x 10(5) attached cells.cm-2 on glass coupons. Light production was found to correlate with biofilm lipid synthesis on a per unit area basis (1-C-14-acetate incorporation). Light correlated directly with sessile bacterial acridine orange direct counts in the range of 10(5) - 10(7) cells.cm-2, providing on-line detection of both biofilm and bulk phase biomass and specific metabolic activity when induced.