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Inhibitors of biofilm formation by biofuel fermentation contaminants

Timothy D. Leathers, Kenneth M. Bischoff, Joseph O. Rich, Neil P.J. Price, Pennapa Manitchotpisit, Melinda S. Nunnally, Amber M. Anderson
Bioresource technology 2014 v.169 pp. 45-51
Bacillus subtilis, Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus plantarum, bacteriophages, biofilm, biofuels, citrates, endolysin, ethanol fuels, fermentation, polysaccharides, xylitol
Biofuel fermentation contaminants such as Lactobacillus sp. may persist in production facilities by forming recalcitrant biofilms. In this study, biofilm-forming strains of Lactobacillus brevis, Lactobacillus fermentum, and Lactobacillus plantarum were isolated and characterized from a dry-grind fuel ethanol plant. A variety of potential biofilm inhibitors were tested, including microbial polysaccharides, commercial enzymes, ferric ammonium citrate, liamocins, phage endolysin, xylitol, and culture supernatants from Bacillus sp. A commercial enzyme mixture (Novozyme 188) and culture supernatants from Bacillus subtilis strains ALT3A and RPT-82412 were identified as the most promising biofilm inhibitors. In biofilm flow cells, these inhibitors reduced the density of viable biofilm cells by 0.8–0.9logcfu/cm2. Unlike B. subtilis strain RPT-82412, B. subtilis strain ALT3A and Novozyme 188 did not inhibit planktonic growth of Lactobacillus sp. MALDI-TOF mass spectra showed the production of surfactin-like molecules by both B. subtilis strains, and the coproduction of iturin-like molecules by strain RPT-82412.