Effects of commonly used food preservatives on biofilm formation of Streptococcus mutans in vitro.
OBJECTIVE
Sodium benzoate (SB), potassium sorbate (PS) and sodium nitrite (SN) are commonly used food preservatives. In this in vitro study, the effects of these substances on biofilm formation of Streptococcus mutans were analysed.


METHODS
In addition to the microtiter plate test (MPT), a biofilm reactor containing bovine enamel slabs (BES) was used to study the influence of food preservatives on biofilm formation in 5 independent periods of 4 days each. These included one period with chlorhexidine digluconate (CHX) as a positive control as well as a period with growth medium alone as a negative control. The vitality of the biofilm on BES was detected using live/dead staining and confocal laser scanning microscopy. Additionally, the number of colony forming units (CFU) was determined.


RESULTS
In MPT 0.12% SN significantly reduced the biofilm formation. PS at a concentration of 0.4% tended to inhibit biofilm formation, whereas the inhibition for 0.8% PS was significant. Less inhibition was caused by 0.8% SB. In the biofilm reactor 0.06% of SN, 0.1% of SB and 0.1% PS significantly reduced the covering grade as well as the CFU of the biofilm. Biofilm vitality was reduced significantly by CHX to a level of 32.5% compared to the control. Only SB reduced the vitality to a level of 19.1%. SN and PS showed no influence on biofilm vitality.


CONCLUSIONS
This study indicates the potential of food preservatives as inhibitory agents in S. mutans biofilm formation, which should be kept in mind when studying the effects of conserved food on dental plaque biofilm in situ.
Al-Ahmad
Ali
A
Department of Operative Dentistry and Periodontology, University of Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany. Ali.Al-Ahmad@uniklinik-freiburg.de
Wiedmann-Al-Ahmad
Margit
M
Auschill
Thorsten Mathias
TM
Follo
Marie
M
Braun
Gabriele
G
Hellwig
Elmar
E
Arweiler
Nicole Birgit
NB
D000818:Animals; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002417:Cattle; D015169:Colony Count, Microbial; D005520:Food Preservatives / Q000494:pharmacology*; D018613:Microscopy, Confocal; D020160:Sodium Benzoate / Q000494:pharmacology; D012977:Sodium Nitrite / Q000494:pharmacology; D013011:Sorbic Acid / Q000494:pharmacology; D013295:Streptococcus mutans / Q000187:drug effects*
D005520:Food Preservatives; D012977:Sodium Nitrite; D020160:Sodium Benzoate; D013011:Sorbic Acid