FERMENTATION OF RARE SUGAR KOJIBIOSE BY THE ORAL BACTERIA IS SLOW YET BACTERIA SPECIFIC
Onyango Stanley a*, Nele De Clercq a, Koen Beerens b, Tom Desmet b and Tom Van de Wiele a
a Center for Microbial Ecology and Technology (CMET), Ghent University, Belgium
b Center for Synthetic Biology, Department of Biochemical and Microbial Technology, Ghent University, Belgium
• To evaluate cariogenic properties of kojibiose and trehalose upon incubations with monocultures and synthetic communities of representetive oral bacteria
• Kojibiose resistant to monoculture fermentation except with
• Delayed drop in pH and low organic acid in kojibiose supports its low/non cariogenic properties
• Kojibiose resistance is time dependent and requires bacterial metabolic synergy
• Trehalose not a suitable sucrose alternative as a non cariogenic sugar given their similar fermentation profile
• Further research on biofilm forming properties and interaction with pathobionts/probiotics are needed.
Low organic acids generated from kojibiose and xylitol by the monocultures of the oral bacteria
Incubations with monocultures and synthetic oral bacterial communities
Level and profile of organic acids is community driven
• pH drop in kojibiose by community comprising of Lactobacillus strains remained above 5.5 at 48 h
• pH dropped below 5.5 across all communities for trehalose and sucrose incubations except for sucrose incubation with Lactobacillus community at 48 h
1. Kassebaum NJ, Bernabe E, Dahiya M, Bhandari B, Murray CJ, Marcenes W. 2015.
Global burden of untreated caries: a systematic review and metaregression. J Dent Res 94:650-8.
2. Takahashi N. 2015. Oral Microbiome Metabolism: From "Who Are They?" to "What Are They Doing?". J Dent Res 94:1628-37.
3. Touger-Decker R, van Loveren C. 2003. Sugars and dental caries. The American Journal of Clinical Nutrition 78:881S-892S.
• Rare sugars; kojibiose (α-1, 2) and trehalose (α1, 1) glucobioses are potential sucrose alternatives but their cariogenic properties are not fully characterized.
• Carriogenic potential of sugars; sucrose, trehalose, kojibiose and xylitol tested across 19 representative oral monocolutures and 4 distinct synthetic communities.
• Incubations made in a carbon limited chemically defined medium (M9) at microarophilic condition (6% ), 37oC
• Monitored change in pH and levels of organic acids
pH change depended on synthetic community and time Dental caries
• Caries affects the permanent teeth of nearly 2.5 billion adults and primary teeth of 0.5 billion children1
• Caries process depends on host- substrate-microbiota
• Sucrose fermentation by the oral microbiota mainly associated with caries development1,3
• More organic acid produced by the monocultures in sucrose and trehalose
L. rhamnosusexhibited slight ability to ferment kojibiose by 48h
P. intermediaexceptionally robust to metabolize all sugars in study except kojibiose
• Lactate dominated the organic acid profile in all sugars except in xylitol
• High proportion of acetate and formate generated from trehalose and sucrose
• with communities comprising strict anaerobes
Lactobacilluscomprising communities produced more organic acids from kojibiose Research objective
The level of organic acids by synthetic communities. Synthetic communities comprised of Lact- Lactobacillus strains (4), Strept- Streptococcus strains (7), Strict ana majorly strict anaerobes (8) and Total –(19) community comprising of all the Lactobacillus, Streptococcus and strict anaerobes. N=3 biological replicates
The level of organic acids produced by the monocultures. Results are 11 oral strains which were able to grow in at least one of the sugars n =3 biological replicates
Methodology Change in pH by synthetic communities. Synthetic communities comprised of Lact- Lactobacillus strains (4), Strept- Streptococcus strains (7), Strict ana majorly strict anaerobes (8) and Total –(19) community comprising of all the Lactobacillus, Streptococcus and strict anaerobes. N =3 biological replicates
Conclusions and perspectives
Critical pH 5.5