title: Rapid evaluation of the antibiotic susceptibility of fuel ethanol contaminant biofilms.
abstract: Bacterial contaminants from commercial fuel ethanol production facilities were previously shown to form biofilms as mixed cultures under laboratory conditions. In this study, a rapid assay was developed to simultaneously compare isolates for their ability to form biofilms as pure cultures. A total of 10 strains were isolated from a dry-grind fuel ethanol plant that routinely doses with virginiamycin. These were identified by sequence analysis as six strains of Lactobacillus fermentum, two strains of L. johnsonii, and one strain each of L. mucosae and L. amylovorus. Isolates exhibited a range of susceptibility to virginiamycin in a planktonic assay, with MIC's (minimum inhibitory concentration) of ≤0.5-16 μg/ml. Even though all strains were isolated from a mixed culture biofilm, they varied greatly in their ability to form biofilms as pure cultures. Surprisingly, growth as biofilms did not appear to provide resistance to virginiamycin, even if biofilms were grown for 144 h prior to antibiotic challenge.
authors.affiliation: Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, 1815 North University Street, Peoria, IL 61604, USA. joseph.rich@ars.usda.gov
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Rich
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Leathers
authors.forename: Melinda S
authors.initials: MS
authors.lastname: Nunnally
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Bischoff
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D056804:Biofuels / Q000382:microbiology*; D001681:Biological Assay; D000431:Ethanol / Q000138:chemical synthesis*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D014769:Virginiamycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D056804:Biofuels; D014769:Virginiamycin; D000431:Ethanol