ABSTRACT
Objective To study the molecular mechanism of swarming motility in Citrobacter freundii.Methods Mini-Tn5 transposon was used to induce swarming mutants in Citrobacter freundii.The mutant genes were amplified by inverse-PCR and were then sequenced.Mutants were observed under light microscope and electron microscope to determine the characters of motility and bacterial shape.Results Seven swarming mutants were found to be three gene mutants(wzxB,waaW,waaL) involving LPS synthesis.Moreover,flagellar production of these mutants was abnormal,that is,only small portion of bacterial cells produced flagella normally.The majority of cells tended to aggregate and produced little flagella observed under electron microscope.Conclusion Absence of O-antigen affects the production of flagella and swarming motility of Citrobacter(freundii).