title: SYBR green as a fluorescent probe to evaluate the biofilm physiological state of Staphylococcus epidermidis, using flow cytometry.
abstract: Staphylococcus epidermidis biofilms with different proportions of viable but nonculturable bacteria were used to show that SYBR green (SYBR) may be used as a probe to evaluate the bacterial physiological state using flow cytometry. Biofilms grown in excess glucose presented significantly higher proportions of dormant bacteria than biofilms grown in excess glucose with buffered pH conditions or with exponential-phase planktonic cultures. Bacteria obtained from biofilms with high or low proportions of viable but nonculturable cells were further cultured in broth medium and stained with SYBR at different time points. An association between bacterial growth and SYBR staining intensity was observed. In addition, bacteria presenting higher SYBR fluorescence intensity also stained more intensely with cyanoditolyl tetrazolium chloride, used as a probe to evaluate cellular metabolism. Accordingly, planktonic bacteria treated with rifampicin, an inhibitor of bacterial RNA transcription, presented lower SYBR and cyanoditolyl tetrazolium chloride staining intensity than nontreated bacteria. Overall, our results indicate that SYBR, in addition to being used as a component of LIVE/DEAD stain, may also be used as a probe to evaluate the physiological state of S. epidermidis cells.
authors.affiliation: Laboratório de Imunologia, Departamento de Imunofisiologia e Farmacologia, Instituto de Ciências Biomédicas de Abel Salazar - Universidade do Porto, Portugal.
authors.forename: Filipe
authors.initials: F
authors.lastname: Cerca
authors.forename: Gabriela
authors.initials: G
authors.lastname: Trigo
authors.forename: Alexandra
authors.initials: A
authors.lastname: Correia
authors.forename: Nuno
authors.initials: N
authors.lastname: Cerca
authors.forename: Joana
authors.initials: J
authors.lastname: Azeredo
authors.forename: Manuel
authors.initials: M
authors.lastname: Vilanova
mesh_terms: D052160:Benzothiazoles; D018441:Biofilms / Q000254:growth & development*; D003959:Diamines; D005434:Flow Cytometry / Q000379:methods*; D005456:Fluorescent Dyes; D050296:Microbial Viability; D009930:Organic Chemicals / Q000378:metabolism; D010933:Plankton / Q000254:growth & development*; D011804:Quinolines; D013194:Staining and Labeling / Q000379:methods*; D013212:Staphylococcus epidermidis / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D013778:Tetrazolium Salts / Q000378:metabolism
chemical_list: D052160:Benzothiazoles; D003959:Diamines; D005456:Fluorescent Dyes; D009930:Organic Chemicals; D011804:Quinolines; D013778:Tetrazolium Salts; C098022:SYBR Green I