Identification And Characterization Of Adhesion-related Genes In Aquatic Pathogens

Pathogen adhesion to the cells and mucosal surfaces of the host is a critical step in early infection process.For many pathogenic bacteria,only when they adhere in the sensitive cells through adhesins,can they produce toxins in the focus or invade into deep tissues,eventual penetrate into the tissues of the host.For this reason,bacterial adhesion has been regarded as one of the virulence factors of the pathogenic bacteria.Although adhesion is an important virulence factor for the pathogens,most studies on bacteria adhesion focu on clinical pathogenic bacteria,hardly any fish pathogens have been studied to uncover the mechanisms of their adhesion.To investigate the mechanisms of Vibrio fluvialis adhesion to surface mucus of the host,a mutant library was constructed by the mini-Tn10 transposon mutagenesis system.Five mutants were screened by indrect Elisa and amplied by PCR with the bacterial suspension.The DNA sequence flanking the transposon mutants was determined using TAIL-PCR.Sequence analysis showed three genes associated with adhesion,beta-1,4-mannanase,glyoxalase/bleomycin resistance protein/ dioxy-genase,anaerobic nitric oxide reductase transcription regulator.However,mutant No.34 find none homology gene and No.88 even no flanking squence.The biological characteristics of the wild-type and the mutant strains were investigated.The results showed that the decreased ability of chemokines and biofilm formation in the mutant strain.To further understand the function of flgN in Aeromonas hydrophila,motility,adherence to the mucus and biofilm formation were investigated with the wild type,mutant and complementation.The results showed that the decreased ability of motility,adhesion to mucus and biofilm formation in the mutant strain partial recovered in the complemented flgN+,which suggested that flgN plays an important role in A.hydrophila adhesion to its host.