Impact of flagellar filament length on <i>Campylobacter jejuni</i> for colonization and flagellar-dependent phenotypes

Flagella and flagellar motility are important to propel many bacteria through environments, biofilm formation, and infection of respective hosts. Most often, the importance of flagella for a species has been assessed with mutants lacking flagella altogether or only the extracellular filament while retaining the basal body. We addressed whether altering filament length impacts flagellar-dependent activities for host colonization. We exploited isogenic <i>Campylobacter jejuni</i> mutants that synthesize longer and shorter filaments on average relative to WT to find that production of shorter filaments had greater negative impacts on motility, autoagglutination, and commensal colonization compared to bacteria that produce elongated filaments. Our findings suggest that polar flagellates may produce a flagellar filament of minimal length to achieve flagellar functions and preserve fitness.