Association of Aeromonas caviae polar and lateral flagella with biofilm formation

Aim: To evaluate the association of the polar and lateral flagella with biofilm formation on plastic surfaces in 76 Aeromonas caviae strains isolated from environment (lagoon water), food (vegetables, fish and cheese) and human source (faeces). Methods and Results: Both polar (flaA) and lateral (lafA) flagellin genes have been investigated by means of PCR and colony blot hybridization assays. The ability to form biofilm in polystyrene microtitre plates was evaluated and correlated with the presence and absence from these genes. The flaA and lafA genes had a frequency of 94% and 71%, respectively. All lafA+ strains were also flaA+. Biofilm formation was observed in 72% of strains. Ninety-four per cent of flaA+lafA+ strains could form biofilm and those that presented an intense biofilm production harboured both genes. All flaA-lafA- isolates, as well as 76% of flaA+lafA- strains, were incapable of forming biofilm. All the fish strains were flaA+lafA+ and displayed higher biofilm formation (88%). Lagoon water samples exhibited lower positivity rate for the lafA gene (57%) and decreased ability to produce biofilm (39%). Conclusions: Both polar and lateral flagellar function contribute to biofilm formation in Aer. caviae strains. Significance and Impact of the Study: This study provides evidence for the association of both flagella with biofilm formation, a factor required for pathogenicity of Aer. caviae strains of varied sources, especially food and human.