Affiliation:
1. Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
Abstract
ABSTRACT
Bacteria growing in biofilms are responsible for a large number of persistent infections and are often more resistant to antibiotics than are free-floating bacteria. In a previous study, we identified a
Pseudomonas aeruginosa
gene,
ndvB
, which is important for the formation of periplasmic glucans. We established that these glucans function in biofilm-specific antibiotic resistance by sequestering antibiotic molecules away from their cellular targets. In this study, we investigate another function of
ndvB
in biofilm-specific antibiotic resistance. DNA microarray analysis identified 24 genes that were responsive to the presence of
ndvB
. A subset of 20 genes, including 8 ethanol oxidation genes (
ercS
′,
erbR
,
exaA
,
exaB
,
eraR
,
pqqB
,
pqqC
, and
pqqE
), was highly expressed in wild-type biofilm cells but not in Δ
ndvB
biofilms, while 4 genes displayed the reciprocal expression pattern. Using quantitative real-time PCR, we confirmed the
ndvB
-dependent expression of the ethanol oxidation genes and additionally demonstrated that these genes were more highly expressed in biofilms than in planktonic cultures. Expression of
erbR
in Δ
ndvB
biofilms was restored after the treatment of the biofilm with periplasmic extracts derived from wild-type biofilm cells. Inactivation of ethanol oxidation genes increased the sensitivity of biofilms to tobramycin. Together, these results reveal that
ndvB
affects the expression of multiple genes in biofilms and that ethanol oxidation genes are linked to biofilm-specific antibiotic resistance.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
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