Identification of gene(s) associated with the biofilm formation of Actinomyces oris

Abstract

It is well known that biofilm-forming bacteria cause chronic or persistent infections. The attachment property is an important factor in early biofilm development. However, the genes associated with attachment on a variety of abiotic materials remain poorly understood. The aim of this study was to identify gene(s) responsible for attachment to abiotic materials in a clinically isolated Actinomyces oris strain K 20 (strain K 20), which is a biofilm-forming strain that continuously produces mannose-rich exopolysaccharide. We performed a random mutagenesis to strain K 20 by using EZ-Tn 5^<TM> <KAN-2> Tnp Transposome^<TM> (EZ-Tn 5). Screening by adhesion activity on glass or polystyrene surfaces identified one hyper adherent mutant among 904 isolated transposants. The gene disrupted by the transposon insertion was determined by direct genome sequencing with the EZ-Tn 5 transposon-end primers. This mutant, designated as strain M 5-7, had a transposon insertion within a gene encoding a polypeptide with membrane-spanning domains. Hydropathy plot and PSI-BLAST analysis implied that this gene might belong to the transporter family, which includes permease.