poster abstractStenotrophomonas maltophilia is an emerging Cystic Fibrosis (CF) lung pathogen,
which displays high intrinsic resistance to a number of different antibiotics.
Additionally, S. maltophilia is thought to increase antibiotic resistance by forming
biofilms during infection. Biofilm disruption could promote clearance of the
microorganism from CF-infected lungs. However, the genetic, biochemical and
immunological mechanisms underlying S. maltophilia biofilm formation are not well
understood. Secreted polysaccharides have been proven to form a vital component of
the matrix that surrounds and protects biofilm bacteria. Hundreds of S. maltophilia
mutants were generated by transposon mutagenesis and screened for strains with
reduced polysaccharide secretion.. These strains were screened through the use of agar
plates containing the polysaccharide-binding dye, Congo red. Experimental controls
included a S. maltophilia wild-type strain (positive control) and a confirmed
polysaccharide deficient mutant (negative control). A Congo red liquid binding assay
was utilized to identify the amount of Congo red bound in the samples, which
confirmed the amount of polysaccharide present in them. A total of 1,728 mutants were
screened with 61 mutants showing reduced polysaccharide production. The mutants
were further narrowed down to 8 samples showing the most consistent phenotype.
Arbitrary-primed polymerase chain reactions (AP-PCR), followed by sequencing, will
be performed on the selected samples in an effort to identify the genes mutated in
polysaccharide deficient strains. We will also perform immunological assays in an
effort to understand underlying immune responses to S. maltophilia. In order to
determine the effects of the deletion of gpmA in S. maltophilia, we will be performing
an in-vitro co-culture assay using the wild-type strain and the gpmA mutant strain.
These studies will yield evidence to the molecular process involved in polysaccharide
production, which could lead to mechanisms to disrupt biofilm formation in CF
patients
