Systematic Inactivation And Functional Identification Of Histidine Kinase Genes Controlling Biofilm Formation Of Bacterial Pathogen Stenotrophomonas Maltophilia

Stenotrophomonas maltophilia(Sma),an opportunistic,nosocomial bacterial pathogen,recently has emerged as one of the most formidable pathogens in hospital and threatens the health of patients with suppressed or compromised immune systems.Due to the capability of biofilm formation,Sma can survive worse environmental conditions and be more resistant to various antibiotics.However,little is known about the molecular mechanisms involved in regulating biofilm formation.Twocomponent signal transduction system(TCSTS),which plays an important role in bacterial physiology,is one of the most predominant regulatory mechanisms employed by prokaryotes to respond and react to stimuli by modulating the gene expression and cellular behaviors.In the present study,We construct a mutant library of the histidine kinase genes by insertional inactivation using the suicide vector pK18 mob.Phenotypic characterization idendified a number of candidate genes involved in cellular morphology,swimming motility,and biofilm development.Among them,bfmK and its cognate response regulator gene bfmA were geneticly proved to be involved in biofilm regulation.To dissect BfmKBfmA regulon,bioinformatics analyses together with molecular analyses confirmed that BfmA acts as a transcriptional regulator to control the transcription of its own operon and acoT,a gene encoding acyl-CoA thioesterases.To our knowledge,this is the first study to systematically investigate the biological functions of histidine kinase genes in the important bacterial pathogen.It will give insight into future studies on the signal transduction of S.maltophilia and facilitate the development of novel therapy method to defend this pathogen.