Susceptibility of wine spoilage yeasts and bacteria in the planktonic state and in biofilms to disinfectants

The aim of this work was to determine the ability of six yeast and two bacterial species associated with wine spoilage to form biofilms in mono- or co-culture using the Calgary Biofilm Device (CBD). Moreover, the efficacy of several disinfectants was evaluated against these spoilage microorganisms, both in the planktonic and the biofilm states. Results showed that Dekkera bruxellensis, Saccharomyces cerevisiae, Saccharomycodes ludwigii, Schizosaccharomyces pombe and Acetobacter aceti formed biofilms both in wine and in synthetic medium. Zygosaccharomyces bailii formed biofilm only in wine and Pichia guilliermondii and Lactobacillus hilgardii formed biofilms only in synthetic medium. In wine, D. bruxellensis presented the same biofilm population when grown in pure culture or in mixed culture with acetic acid bacteria. There was a 3-log increase in biofilm formed by A. aceti in mixed culture with L. hilgardii. Alkaline chlorine-based disinfectant was the most effective in decontaminating spoilage yeast and bacteria both in planktonic and biofilm tests. Sodium hydroxide-based detergents and peracetic-based disinfectant were also efficient against suspended cells, but at least 10-fold more concentrated solutions were needed to remove the biofilms. Furthermore, the results showed that, except for the neutral detergent VK10, the tested agents were actually effective when used under the conditions recommended by manufacturers. In any case, biofilms showed greater tolerance to biocides when compared to the same microorganisms in the planktonic state. To our knowledge, this is the first study in which the CBD is used to assess the ability of wine spoilage microorganisms to form biofilms and their susceptibilities to disinfectant agents.