Identification of two flagellar genes required for biofilm formation in a Salmonella enterica serovar Typhimurium

Abstract

Biofilm plays an important role in pathogenicity of Salmonella enterica serovar Typhimurium. To understand the molecular mechanism of biofilm formation by S. Typhimurium, a library of random mutagenized clones was constructed using the commercial Tn5 transposon EZ::TN™ < KAN-2 > Tnp Transposome™ (Epicentre). This library was screened for phenotypic analyses of their ability to form biofilm and 5 mutants were confirmed to be biofilm deficient. From these mutants, the insertion site flanking sequences were amplified by inverse PCR followed by sequencing. Three mutants had a transposon insertion in flgA gene encoding for flagellar basal body P-ring biosynthesis protein that is required for assembly of the flagellar basal body P-ring. Two mutants had a transposon insertion in the FlgB gene encoding for flagellar component of cellproximal portion of basal-body rod. These mutants were non-motile as confirmed by MSRVand transmission electron microscope suggesting that motility was necessary for biofilm development in S. Typhimurium. © Springer-Verlag and the University of Milan 2011.