ONLINE MONITORING OF ANTIFOULING AND FOULING-RELEASE SURFACES USING BIOLUMINESCENCE AND FLUORESCENCE MEASUREMENTS DURING LAMINAR-FLOW

A laminar flow biofilm-monitoring system was used to determine the eff icacies of three antifouling (AF) coatings and five fouling-release (F R) coatings against Vibrio harveyi attachment. On-line measurements of tryptophan fluorescence and bioluminescence from each coating, normal ized to an upstream stainless steel coupon, were used to determine the effects of AF and FR surfaces on biofilm formation. The AF coatings c onsisted of 5, 10, and 35 wt% Sea Nine 211 (C9211) incorporated into a vinyl copolymer. Both the 10 and 35 wt% coatings significantly inhibi ted biofilm biomass development measured by tryptophan fluorescence co mpared to the stainless steel control. V. harveyi bioluminescence was significantly greater than tryptophan fluorescence in cells attached t o these coatings, suggesting that bioluminescence expression may be a marker for cellular stress or toxicity in biofilms. Five different pol ydimethylsiloxane (PDMS) FR coatings did not inhibit biofilm formation under low flow conditions. However, four PDMS coatings demonstrated d ecreased biomass levels compared to stainless steel after exposure to a shear stress of 330 dynes cm(-2). There was no toxic additive in the se coatings; bioluminescence and tryptophan fluorescence were proporti onal.