Determining the suitability of Lactobacilli antifungal metabolites for inhibiting mould growth

In recent years, public concern about indoor mould growth has increased dramatically in the United States. In this study, lactic acid bacteria (LAB), which are known to produce antimicrobial compounds important in the biopreservation of food, were evaluated to determine if the same antimicrobial properties can be used to inhibit mould fungi that typically colonize wood. Based on biomass measurement, cell-free supernatants from Lactobacillus casei subsp. rhamnosus and Lactobacillus acidophilus grown in deMan Rogosa Sharpe (MRS) broth inhibited 95100% growth of three mould fungi and one stain fungus associated with wood-based building materials. Lactic acid and four unknown compounds < 1 kDa molecular weight were fractionated from the culture supernatant by thin layer chromatography and high-performance liquid chromatography. Antifungal activity, which was attributed to one or more unknown metabolites, was retained during heating and neutralization. A 1:2 dilution of L. casei supernatant inhibited 100% growth of all test fungi.