Dietary sugar utilisation by putative oral probiotics

Probiotic consumption and repeated probiotic intake have shown promising results as adjunct therapies in prevention and alleviation of some chronic disease conditions in the gastrointestinal tract. Recent evidence suggests that probiotics may also be beneficial in preventing oral diseases. An efficient probiotic candidate in the mouth, however, should not impose any risk to oral tissues, such as acid demineralisation of tooth enamel because of sugar fermentation. The aim of the present in vitro study was to evaluate the utilisation of some sugars and sugar alcohols by yogurt starter Lactobacillus delbrueckii subsp. bulgaricus strains and to assess the influence of these carbohydrate sources on cell surface properties. For comparsion, a commercially available probiotic, Lactobacillus rhamnosus GG, was used. The results showed that lactose, glucose and fructose were readily metabolised by all strains tested. However, strain-specific metabolic patterns were observed when other sugars and sugar alcohols were used as sole carbohydrate source in the growth medium. Surface properties of the bacteria such as hydrophobicity and surface-associated proteins appeared to vary with the carbohydrate content of the growth medium. Based on these results it can be concluded that among the L. delbrueckii subsp. bulgaricus strains probiotic candidate strains are available that warrant further studies due to their inability to ferment sugars with pronounced cariogenic properties.