Affiliation:
1. Institut für Medizinische Mikrobiologie und Immunologie, Universitäts-Krankenhaus Eppendorf, D-20246 Hamburg, Federal Republic of Germany
Abstract
ABSTRACT
The formation of adherent multilayered biofilms embedded into a glycocalyx represents an essential factor in the pathogenesis of
Staphylococcus epidermidis
biomaterial-related infections. Using biofilm-producing
S. epidermidis
1457 and transposon Tn
917
carried on plasmid pTV1ts, we isolated nine isogenic biofilm-negative transposon mutants. Transduction by
S. epidermidis
phage 71 was used to prove the genetic linkage of transposon insertions and altered phenotypes. Mapping of the different transposon insertions by Southern hybridization and pulsed-field gel electrophoresis indicated that these were inserted in four unlinked genetic loci. According to their phenotypes, including quantitative differences in biofilm production in different growth media, in the amount of the polysaccharide intercellular adhesin (PIA) produced, in the hemagglutination titers, and in the altered colony morphology, the mutants could be separated into four phenotypic classes corresponding with the genetic classes. Synthesis of PIA was not detectable with class I and II mutants, whereas the amount of PIA produced reflected the residual degree of biofilm production of class III and IV mutants in different growth media. Chromosomal DNA flanking the transposon insertions of five class I mutants was cloned and sequenced, and the insertions were mapped to different locations of
icaADBC
, representing the synthetic genes for PIA. Expression of
icaADBC
from a xylose-dependent promoter in the different isogenic mutant classes reconstituted biofilm production in all mutants. In a Northern blot analysis no
icaADBC
-specific transcripts were observed in RNA isolated from mutants of classes II, III, and IV. Apparently, in addition to
icaADBC
, three other gene loci have a direct or indirect regulatory influence on expression of the synthetic genes for PIA on the level of transcription.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
104 articles.
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