Limits...
Effect of iron on the expression of sirR and sitABC in biofilm-associated Staphylococcus epidermidis.

Massonet C, Pintens V, Merckx R, Anné J, Lammertyn E, Van Eldere J - BMC Microbiol. (2006)

Bottom Line: In vitro in a Fe-limited environment, the planktonic form of S. epidermidis produces siderophores and grows slower than in Fe-rich environment.The expression of sitC was not inversely correlated to sirR expression.In vivo, expression levels of sirR and of sitABC were high during the initial phase after implantation and, after a transient decrease, remained stable over a period of two weeks.

View Article: PubMed Central - HTML - PubMed

Affiliation: Lab medical microbiology, Department Medical Diagnostic Sciences, KULeuven, U,Z,Gasthuisberg, Herestraat 49 CDG8th floor, B-3000, Leuven, Belgium. caroline.massonet@med.kuleuven.be

ABSTRACT

Background: Different gene expression patterns correlate with the altered phenotype in biofilm-associated bacteria. Iron and iron-linked genes are thought to play a key-role in biofilm formation. The expression of Fe-linked genes (sirR, sitABC operon) in Staphylococcus epidermidis, was compared in planktonic versus sessile bacteria in vitro and in vivo in a subcutaneous foreign body rat model.

Results: In vitro in a Fe-limited environment, the planktonic form of S. epidermidis produces siderophores and grows slower than in Fe-rich environment. The expression of sirR in planktonic bacteria, in vitro, was not different in medium without Fe or with 1 microM FeCl3. High Fe concentrations (25 microM FeCl3) increased expression of sirR transiently during the early phase of incubation. Expression of sitC in vitro, in planktonic bacteria, was inversely correlated with sirR expression in medium with 25 microM FeCl3: sitC expression decreased for the first 3 hours followed by an up regulation.In sessile bacteria in vitro, sirR expression was high and independent of the Fe concentration. The expression of sitC was not inversely correlated to sirR expression. In vivo, expression levels of sirR and of sitABC were high during the initial phase after implantation and, after a transient decrease, remained stable over a period of two weeks.

Conclusion: Our data suggest that the expression of sirR and the regulatory effect of sirR on the sitABC operon are different in planktonic and sessile bacteria.

Show MeSH

Related in: MedlinePlus

In vitro gene expression of sirR (a, b and c) and sitC (d, e and f) in planktonic bacteria. Gene expression is quantified as log10 (cDNA/gDNA) in the y-axis. The line that links the data points helps to clarify the results at each time point measured. The error bars represent standard deviations. Fifteen samples from three independent cultures were assessed at each time point. Time is given in hours in the x-axis. (a) and (d): bacteria pre-incubated overnight in BHI and incubated in fRPMI (full line with empty circle) or fRPMI-Fe1 (full line with filled triangle). (b) and (e): bacteria pre-incubated overnight in fRPMI and incubated in fRPMI (full line with filled diamond) and in fRPMI-Fe1 (full line with filled square). (c) and (f): bacteria pre-incubated overnight in fRPMI and incubated in fRPMI (dotted line with filled diamond) or in fRPMI-Fe25 (full line with empty triangle).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC1764749&req=5

Figure 2: In vitro gene expression of sirR (a, b and c) and sitC (d, e and f) in planktonic bacteria. Gene expression is quantified as log10 (cDNA/gDNA) in the y-axis. The line that links the data points helps to clarify the results at each time point measured. The error bars represent standard deviations. Fifteen samples from three independent cultures were assessed at each time point. Time is given in hours in the x-axis. (a) and (d): bacteria pre-incubated overnight in BHI and incubated in fRPMI (full line with empty circle) or fRPMI-Fe1 (full line with filled triangle). (b) and (e): bacteria pre-incubated overnight in fRPMI and incubated in fRPMI (full line with filled diamond) and in fRPMI-Fe1 (full line with filled square). (c) and (f): bacteria pre-incubated overnight in fRPMI and incubated in fRPMI (dotted line with filled diamond) or in fRPMI-Fe25 (full line with empty triangle).

Mentions: After overnight pre-incubation of S. epidermidis in BHI and resuspension of the bacteria in fRPMI-Fe1 and in fRPMI (Fig. 2a) the expression of sirR remained at a constant low level, independently of the Fe-content of the medium. The same results were obtained when fRPMI was used for overnight pre-incubation instead of BHI (Fig. 2b). However, after pre-incubation in fRPMI and re-incubation in fRPMI versus fRPMI with 25 μM FeCl3 (fRPMI-Fe25), differences in sirR expression were observed (Fig. 2c). In fRPMI-Fe25 sirR expression increased during the first 2 hrs (one-way ANOVA; Bonferroni; p < 0.001), followed by a decrease (one-way ANOVA; Bonferroni; p < 0.05) to the level of expression of sirR observed in fRPMI.


Effect of iron on the expression of sirR and sitABC in biofilm-associated Staphylococcus epidermidis.

Massonet C, Pintens V, Merckx R, Anné J, Lammertyn E, Van Eldere J - BMC Microbiol. (2006)

In vitro gene expression of sirR (a, b and c) and sitC (d, e and f) in planktonic bacteria. Gene expression is quantified as log10 (cDNA/gDNA) in the y-axis. The line that links the data points helps to clarify the results at each time point measured. The error bars represent standard deviations. Fifteen samples from three independent cultures were assessed at each time point. Time is given in hours in the x-axis. (a) and (d): bacteria pre-incubated overnight in BHI and incubated in fRPMI (full line with empty circle) or fRPMI-Fe1 (full line with filled triangle). (b) and (e): bacteria pre-incubated overnight in fRPMI and incubated in fRPMI (full line with filled diamond) and in fRPMI-Fe1 (full line with filled square). (c) and (f): bacteria pre-incubated overnight in fRPMI and incubated in fRPMI (dotted line with filled diamond) or in fRPMI-Fe25 (full line with empty triangle).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1764749&req=5

Figure 2: In vitro gene expression of sirR (a, b and c) and sitC (d, e and f) in planktonic bacteria. Gene expression is quantified as log10 (cDNA/gDNA) in the y-axis. The line that links the data points helps to clarify the results at each time point measured. The error bars represent standard deviations. Fifteen samples from three independent cultures were assessed at each time point. Time is given in hours in the x-axis. (a) and (d): bacteria pre-incubated overnight in BHI and incubated in fRPMI (full line with empty circle) or fRPMI-Fe1 (full line with filled triangle). (b) and (e): bacteria pre-incubated overnight in fRPMI and incubated in fRPMI (full line with filled diamond) and in fRPMI-Fe1 (full line with filled square). (c) and (f): bacteria pre-incubated overnight in fRPMI and incubated in fRPMI (dotted line with filled diamond) or in fRPMI-Fe25 (full line with empty triangle).
Mentions: After overnight pre-incubation of S. epidermidis in BHI and resuspension of the bacteria in fRPMI-Fe1 and in fRPMI (Fig. 2a) the expression of sirR remained at a constant low level, independently of the Fe-content of the medium. The same results were obtained when fRPMI was used for overnight pre-incubation instead of BHI (Fig. 2b). However, after pre-incubation in fRPMI and re-incubation in fRPMI versus fRPMI with 25 μM FeCl3 (fRPMI-Fe25), differences in sirR expression were observed (Fig. 2c). In fRPMI-Fe25 sirR expression increased during the first 2 hrs (one-way ANOVA; Bonferroni; p < 0.001), followed by a decrease (one-way ANOVA; Bonferroni; p < 0.05) to the level of expression of sirR observed in fRPMI.

Bottom Line: In vitro in a Fe-limited environment, the planktonic form of S. epidermidis produces siderophores and grows slower than in Fe-rich environment.The expression of sitC was not inversely correlated to sirR expression.In vivo, expression levels of sirR and of sitABC were high during the initial phase after implantation and, after a transient decrease, remained stable over a period of two weeks.

View Article: PubMed Central - HTML - PubMed

Affiliation: Lab medical microbiology, Department Medical Diagnostic Sciences, KULeuven, U,Z,Gasthuisberg, Herestraat 49 CDG8th floor, B-3000, Leuven, Belgium. caroline.massonet@med.kuleuven.be

ABSTRACT

Background: Different gene expression patterns correlate with the altered phenotype in biofilm-associated bacteria. Iron and iron-linked genes are thought to play a key-role in biofilm formation. The expression of Fe-linked genes (sirR, sitABC operon) in Staphylococcus epidermidis, was compared in planktonic versus sessile bacteria in vitro and in vivo in a subcutaneous foreign body rat model.

Results: In vitro in a Fe-limited environment, the planktonic form of S. epidermidis produces siderophores and grows slower than in Fe-rich environment. The expression of sirR in planktonic bacteria, in vitro, was not different in medium without Fe or with 1 microM FeCl3. High Fe concentrations (25 microM FeCl3) increased expression of sirR transiently during the early phase of incubation. Expression of sitC in vitro, in planktonic bacteria, was inversely correlated with sirR expression in medium with 25 microM FeCl3: sitC expression decreased for the first 3 hours followed by an up regulation.In sessile bacteria in vitro, sirR expression was high and independent of the Fe concentration. The expression of sitC was not inversely correlated to sirR expression. In vivo, expression levels of sirR and of sitABC were high during the initial phase after implantation and, after a transient decrease, remained stable over a period of two weeks.

Conclusion: Our data suggest that the expression of sirR and the regulatory effect of sirR on the sitABC operon are different in planktonic and sessile bacteria.

Show MeSH
Related in: MedlinePlus