Production of Cellulose and Curli Fimbriae by Members of the Family <i>Enterobacteriaceae</i> Isolated from the Human Gastrointestinal Tract

<jats:title>ABSTRACT</jats:title> <jats:p> <jats:italic>Citrobacter</jats:italic> spp., <jats:italic>Enterobacter</jats:italic> spp., and <jats:italic>Klebsiella</jats:italic> spp. isolated from the human gut were investigated for the biosynthesis of cellulose and curli fimbriae ( <jats:italic>csg</jats:italic> ). While <jats:italic>Citrobacter</jats:italic> spp. produced curli fimbriae and cellulose and <jats:italic>Enterobacter</jats:italic> spp. produced cellulose with various temperature-regulatory programs, <jats:italic>Klebsiella</jats:italic> spp. did not show pronounced expression of those extracellular matrix components. Investigation of multicellular behavior in two <jats:italic>Citrobacter</jats:italic> species and <jats:italic>Enterobacter sakazakii</jats:italic> showed an extracellular matrix, cell clumping, pellicle formation, and biofilm formation associated with the expression of cellulose and curli fimbriae. In those three strains, the <jats:italic>csgD-csgBA</jats:italic> region and the cellulose synthase gene <jats:italic>bcsA</jats:italic> were conserved. PCR screening for the presence of <jats:italic>csgD, csgA</jats:italic> and <jats:italic>bcsA</jats:italic> revealed that besides <jats:italic>Klebsiella pneumoniae</jats:italic> and <jats:italic>Klebsiella oxytoca,</jats:italic> all species investigated harbored the genetic information for expression of curli fimbriae and cellulose. Since <jats:italic>Citrobacter</jats:italic> spp., <jats:italic>Enterobacter</jats:italic> spp., and <jats:italic>Klebsiella</jats:italic> spp. are frequently found to cause biofilm-related infections such as catheter-associated urinary tract infections, the human gut could serve as a reservoir for dissemination of biofilm-forming isolates. </jats:p>