Biofilm-positive mutant LM-49 from the food-borne pathogen Listeria monocytogenes was characterized to investigate the mechanisms controlling biofilm formation in this bacterium.The mutation was generated via transposon insertion within the coding region of the gene encoding a homologue of Lmof2365_1771 ofL.monocytogenes str.4b F2365.This ORF,denoted Lm.G_1771,encoded a putative permease with 10 transmembrane helixes.To demonstrate that Tn917 insertion within Lm.G_1771 in the mutant (Tn917:Lm.G_1771) was solely responsible for the enhanced biofilm formation,a revertant was constructed by replacing the mutant allele with the wild-type gene via homologous recombination.