Formation of In Vitro Mixed-Species Biofilms by Lactobacillus pentosus and Yeasts Isolated from Spanish-Style Green Table Olive Fermentations

Abstract

The present work studies the in vitro interactions between Lactobacillus pentosus and yeast strains isolated from table olive processing to form mixed biofilms. Among the different pairs assayed, the strongest biofilms were obtained from L. pentosus and Candida boidinii strain co-cultures. However, biofilm formation was inhibited in the presence of D(+)-mannose. In addition, biofilm formation by C. boidinii mono-cultures was stimulated in the absence of cell-cell contact with L. pentosus. Scanning electron microscopy revealed that a sort of “sticky” material formed by the yeasts contributed to its substrate adherence. Hence, the data obtained in this work suggests that yeast-lactobacilli biofilm may be favored by the presence of a specific mate of yeast-L. pentosus, and that more than one mechanism could be implicated in the biofilm formation. This knowledge will help for designing appropriate mixed starter cultures of pairs of L. pentosus-yeast species able to improve the quality and safety of Spanish-style green table olive processing.