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| Content Provider | PubMed Central |
|---|---|
| Author | Allegrucci, Magee Sauer, Karin |
| Abstract | In this report, we show that biofilm formation by Streptococcus pneumoniae serotype 19 gives rise to variants (the small mucoid variant [SMV] and the acapsular small-colony variant [SCV]) differing in capsule production, attachment, and biofilm formation compared to wild-type strains. All biofilm-derived variants harbored SNPs in cps19F. SCVs reverted to SMV, but no reversion to the wild-type phenotype was noted, indicating that these variants were distinct from opaque- and transparent-phase variants. The SCV-SMV reversion frequency was dependent on growth conditions and treatment with tetracycline. Increased reversion rates were coincident with antibiotic treatment, implicating oxidative stress as a trigger for the SCV-SMV switch. We, therefore, evaluated the role played by hydrogen peroxide, the oxidizing chemical, in the reversion and emergence of variants. Biofilms of S. pneumoniae TIGR4-ΔspxB, defective in hydrogen peroxide production, showed a significant reduction in variant formation. Similarly, supplementing the medium with catalase or sodium thiosulfate yielded a significant reduction in variants formed by wild-type biofilms. Resistance to rifampin, an indicator for mutation frequency, was found to increase approximately 55-fold in biofilms compared to planktonic cells for each of the three wild-type strains examined. In contrast, TIGR4-ΔspxB grown as a biofilm showed no increase in rifampin resistance compared to the same cells grown planktonically. Furthermore, addition of 2.5 and 10 mM hydrogen peroxide to planktonic cells resulted in a 12- and 160-fold increase in mutation frequency, respectively, and gave rise to variants similar in appearance, biofilm-related phenotypes, and distribution of biofilm-derived variants. The results suggest that hydrogen peroxide and environmental conditions specific to biofilms are responsible for the development of non-phase-variable colony variants. |
| Related Links | http://dx.doi.org/10.1128/jb.00707-08 |
| Ending Page | 6339 |
| Page Count | 10 |
| Starting Page | 6330 |
| File Format | |
| ISSN | 00219193 |
| e-ISSN | 10985530 |
| Journal | Journal of Bacteriology |
| Issue Number | 19 |
| Volume Number | 190 |
| Language | English |
| Publisher | American Society for Microbiology (ASM) |
| Publisher Date | 2008-10-01 |
| Access Restriction | Open |
| Rights Holder | American Society for Microbiology (ASM) |
| Subject Keyword | Molecular Biology Microbiology Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Molecular Biology Microbiology |
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