Inhibition of Saccharomyces cerevisiae by slow release of propyl paraben from a polymer coating

The inhibition of Saccharomyces cerevisiae by slow release of propyl parabe n from a styrene-acrylate copolymer coating was examined and compared with the inhibition by direct addition of propyl paraben. Under slow release con dition, a slow but continuous microbial inhibition was observed, whereas a cell outgrowth was observed under direct addition condition after a suffici ent incubation time. S. cerevisiae cells isolated from the culture under di rect addition condition were more tolerant of propyl paraben than cells iso lated from the culture under slow release condition. The equilibrium propyl paraben concentrations under both conditions were 150 ppm. The release kin etics of propyl paraben from the coating at 30 degreesC was found to be con trolled by Fickian diffusion within the coating. The estimated partition an d diffusion coefficients were 4.65 X 10(-3) and 2.01 X 10(-10) cm(2)/s. res pectively.