The effect of pediocin PD-1, plantaricin 423, and nisin was tested against established biofilms formed by a commercial starter culture of Oenococcus oeni on stainless steel slides and planktonic (free-living) cells. The percentage viable and nonviable cells were determined by using a viability probe and an epifluorescence microscope with image analysis. Pediocin PD-1 (3000 AU/mL) removed all cells in a biofilm of O. oeni that formed in acidic grape medium after five hours. Plantaricin 423 (3000 AU/mL) and nisin (3000 AU/mL) killed all viable cells in the biofilm. However, approximately 42 and 49% of the original cells on the stainless steel surface remained attached, with the majority staining nonviable when treated with the latter two peptides, respectively. In a modified Chardonnay must, all cells (viable and nonviable) of O. oeni in the biofilm were removed after one hour when treated with pediocin PD-1 (3000 AU/mL). In similar experiments, treatment with plantaricin 423 and nisin resulted in undetectable numbers of viable cells in the biofilm. Approximately 36 and 43% of the original cells on the stainless steel surface remained attached, with the majority staining nonviable after five hours of treatment with the latter two peptides, respectively. After five hours of treatment with the respective antimicrobial peptides (3000 AU/mL), the planktonic cell numbers of O. oeni decreased from 1.3 x 1010 cfu/mL to undetectable numbers of viable cells in acidic grape medium. The same experiment performed in modified Chardonnay must yielded no detectable cells of O. oeni.
Acknowledgments: The authors thank Distell Corporation for supplying the Chardonnay must and Wineland Engineers CC for supplying the stainless steel slides. Research was funded by a grant from Winetech SA.
- Copyright 2002 by the American Society for Enology and Viticulture