Control of Glucose- and NaCl-Induced Biofilm Formation by rbf in Staphylococcus aureus

Abstract

Both Staphylococcus aureus and S. epidermidis are capable of forming biofilm on biomaterials. We used Tn917 mutagenesis to identify a gene, rbf, affecting biofilm formation in S. aureus NCTC8325-4. Sequencing revealed that Rbf contained a consensus region signature of the AraC/XylS family of regulators, suggesting that Rbf is a transcriptional regulator. Insertional duplication inactivation of the rbf gene confirmed that the gene was involved in biofilm formation on polystyrene and glass. Phenotypic analysis of the wild type and the mutant suggested that the rbf gene mediates the biofilm formation of S. aureus at the multicellular aggregation stage rather than at initial attachment. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis demonstrated that the mutation resulted in the loss of an ϳ190-kDa protein. Biofilm production by the mutant could be restored by complementation with a 2.5-kb DNA fragment containing the rbf gene. The rbf-specific mutation affected the induction of biofilm formation by glucose and a high concentration of NaCl but not by ethanol. The mutation did not affect the transcription of the ica genes previously shown to be required for biofilm formation. Taken together, our results suggest that the rbf gene is involved in the regulation of the multicellular aggregation step of S. aureus biofilm formation in response to glucose and salt and that this regulation may be mediated through the 190-kDa protein.

Staphylococcal Biofilms

“…We will focus on regulators, for which a mechanism for the influence on biofilm formation has been described in more detail. There are several regulatory systems described in the literature, such as the rbf (regulator of biofilm formation) (Lim et al 2004), for which this is still elusive. In addition, very recent reports suggest that the effect that has been described for the Trap regulator, allegedly affecting biofilm formation in response to a peptide called RIP (Balaban et al 2003;Balaban et al 2007), is not genuine but due to a second site mutation, most likely in the agr system (Shaw et al 2007;Tsang et al 2007).…”

The cidA murein hydrolase regulator contributes to DNA release and biofilm development in Staphylococcus aureus

“…Many S. aureus infections are thought to involve the formation of biofilm, surface-associated communities of microbes encompassed by an extracellular matrix (1,2). Several S. aureus genes have been reported to contribute to its biofilm-forming ability, including agr (3)(4)(5), sarA (5-7), sigB (8), ica (9), rbf (10), tcaR (11), arlRS (12,13), and alsSD (14). Microarray analyses of S. aureus (15,16), Pseudomonas aeruginosa (17,18), Bacillus subtilis (19,20), and Escherichia coli (21) have also illustrated that there are major differences in gene expression between biofilm and planktonic cultures of these organisms.…”

Acoustic vibration can enhance bacterial biofilm formation

“…alone (Stavridou and Forzi, 2011). The formation of biofilms is thought to be governed by a diverse number of factors, including nutritional availability (Lim et al 2004), osmolarity (Karatan and Watnick, 2009), self-generated quorum sensing signals (De Kievit, 2009) and the chemistry and topography of the host surface (MacKintosh et al 2006). Much work has gone into trying to disrupt or prevent biofilm formation, some of which has focussed on using ultrasound (Hazan et al 2006).…”