Universidade Católica Portuguesa. Escola Superior de Biotecnologia
Abstract
Recent technological advances have made it possible to study global gene
expression in bacteria. Microarrays have emerged as the premier tool for
studying gene expression on a genomic scale and have been used in a broad
range of studies1. Staphylococcus epidermidis and Staphylococcus aureus can
form biofilms on medical devices. The major constituent of the biofilm matrix is
the polysaccharide PNAG, synthesized by the proteins encoded in the icaADBC
locus2. A knockout of the ica locus in a biofilm-forming strain will cause that
strain to lose its ability to form a biofilm. However, what is not known is the effect
of the loss of the icaADBC locus on the overall gene expression by the bacteria.
We used a strong biofilm forming strain of S. aureus and an isogenic icaADBC
knock out and grew them under the same conditions (16H, TSB with 1% glucose,
37°C, 300rpm) after which we extracted the total RNA, and converted it to
cDNA. We then labeled the cDNA with 2 different dyes, and hybridized the
product on a microarray slide containing the genome of S. aureus. The
microarrays were analyzed using an open source software (TM4)3. Data analysis
verified that the majority of the genes were equally expressed by both strains, as
expected. However, approximately 60 genes were differentially expressed
between the wild type and the isogenic mutant, demonstrating that a deletion
mutation within a single locus can influence the expression of many other genes
in the bacteria
