IADR Abstract Archives
Autofluorescence of Biofilm Caries Active Streptococcus Mutans Strains
Objectives: To determine whether Streptococcus mutans (UA159) grown in 0, 1 and 2% sucrose autoflouresces and compare clinical isolates of caries active (CA) and caries resistant (CR) S. mutans strains under biofilm growth conditions.
Methods: S. mutans UA159 was grown for 24 h with 0, 1 and 2% sucrose at 37oC in 5% CO2. CA strains 192 (<105 CFU/ml in saliva from a CA subject) and A32-2 (>105 CFU) and CR strains 314 (< 105 CFU) and 317 (>105 CFU) were grown similar to UA159. A stock solution of Protoporphyrin IX was prepared in 100% ethanol and diluted to a concentration from 1.6-3.1×10-4 g/ml. Emission spectra were measured using a spectrofluorometer by excitation at 385 or 405 nm with 10 nm steps with planktonic fluid on top of the biofilm (total biomass) and only with biofilm. ANOVA was conducted comparing UA159 vs. no UA159 or CA vs. CF strains for total biomass and only with biofilm, based on effects of sucrose concentration, and emitted wavelengths. The analysis was performed using ranked data, allowing sucrose-group combinations to have different variances within each experiment.
Results: Emission spectra at 770 nm were observed with S. mutans strains UA159, CR (314 and 317), CA (192 and A32-2) and Protoporphyrin IX when excited at 385 nm, and 800 nm, and occasionally at 810 nm, when excited at 405 nm. UA159 was significantly higher than without UA159 for all combinations (p<.0005) except total biomass with 2% sucrose at 770 nm (no difference) and at 800 and 810 nm (UA159 lower). CA was significantly higher than CF for all combinations except biofilm only at 810 nm and 2% sucrose at 810 nm.
Conclusions: S. mutans autofluoresces in the red and infrared regions of the electromagnetic spectrum. CA was significantly different than CF for total biomass.
Methods: S. mutans UA159 was grown for 24 h with 0, 1 and 2% sucrose at 37oC in 5% CO2. CA strains 192 (<105 CFU/ml in saliva from a CA subject) and A32-2 (>105 CFU) and CR strains 314 (< 105 CFU) and 317 (>105 CFU) were grown similar to UA159. A stock solution of Protoporphyrin IX was prepared in 100% ethanol and diluted to a concentration from 1.6-3.1×10-4 g/ml. Emission spectra were measured using a spectrofluorometer by excitation at 385 or 405 nm with 10 nm steps with planktonic fluid on top of the biofilm (total biomass) and only with biofilm. ANOVA was conducted comparing UA159 vs. no UA159 or CA vs. CF strains for total biomass and only with biofilm, based on effects of sucrose concentration, and emitted wavelengths. The analysis was performed using ranked data, allowing sucrose-group combinations to have different variances within each experiment.
Results: Emission spectra at 770 nm were observed with S. mutans strains UA159, CR (314 and 317), CA (192 and A32-2) and Protoporphyrin IX when excited at 385 nm, and 800 nm, and occasionally at 810 nm, when excited at 405 nm. UA159 was significantly higher than without UA159 for all combinations (p<.0005) except total biomass with 2% sucrose at 770 nm (no difference) and at 800 and 810 nm (UA159 lower). CA was significantly higher than CF for all combinations except biofilm only at 810 nm and 2% sucrose at 810 nm.
Conclusions: S. mutans autofluoresces in the red and infrared regions of the electromagnetic spectrum. CA was significantly different than CF for total biomass.