Distinct function of Pseudomonas aeruginosa type IV pili disclosed in the bacterial pass-through of membrane filter with smaller pore sizes

Membrane filter pass-through ability of Pseudomonas aeruginosa was analyzed with isogenic mutants. A flagellum-deficient fliC mutant required two-times longer time (12 hr) to pass through a 0.45-microm pore size filter. With 0.3- and 0.22-microm filters, however, the fliC mutant showed no remarkable disability. Meanwhile a pilA mutant defective in twitching motility failed to pass through the 0.22-microm filter. Complementation of the mutant with pilA gene on a plasmid restored the twitching motility and the 0.22-microm filter pass-through activity. Thus, the distinctive role of P. aeruginosa type IV pili in infiltration into finer reticulate structures was indicated.