Influence of Flagella on <i>Salmonella</i> Enteritidis Sedimentation, Biofilm Formation, Disinfectant Resistance, and Interspecies Interactions

Flagella are essential for bacterial motility and biofilm formation by aiding bacterial attachment to surfaces. However, the impact of flagella on bacterial behavior, particularly biofilm formation, remains unclear. This study constructed two flagellar mutation strains of <i>Salmonella</i> Enteritidis (SE), namely, SE-Δ<i>flhD</i> and SE-Δ<i>flgE</i>, and confirmed the loss of flagellar structures and motility in these strains. The mutant strains exhibited growth comparable with the wild-type (WT) strain but had higher sedimentation rates. Biofilm biomass did not differ significantly between the WT and mutant strains, except for SE-Δ<i>flgE</i> at 3 d. SE-Δ<i>flgE</i> showed increased susceptibility to sodium hypochlorite compared to the WT. The co-sedimentation rate of flagella-deficient strains was lower than the WT, and the biomass of dual-species biofilm formed by <i>Bacillus paramycoides</i> B5 with SE-Δ<i>flhD</i> or SE-Δ<i>flgE</i> was significantly lower than with the WT. These findings emphasize the significance of SE flagella in biofilm formation and interspecies interactions, offering insights into targeted biofilm prevention and control measures.