Basic Biological Sciences

Abstract

Of 50 strains of lactobacilli isolated from dental plaque of school children, two strains, provisionally identified as Lactobacillus salivarius, and one strain, provisionally identified as Lactobacillus fermentum, induced significant caries activity in conventional hamsters. Sucrose was a required dietary cariogenic substrate and could not be replaced with glucose or starch. In contrast to cariogenic strains of Streptococcus mutans the active lactobacilli did not form adherent sucrose-mediated plaques in vitro, did not form intracellular iodophilic polysaccharides and did not form detectable insoluble extracellular polyglucans.

Streptococcus mutans Displays Altered Stress Responses While Enhancing Biofilm Formation by Lactobacillus casei in Mixed-Species Consortium

“…as well as their impact on the mixed-species consortium. In an early animal model study by Fitzgerald et al (Fitzgerald et al, 1980 ), it was found that clinic isolates of L. salivarius and L. fermentum were able to induce significant carious activity in conventional hamsters but not on hamsters whose regular oral flora was depressed via polyantibiotics. This also indicates results of likely interactions between members of the indigenous oral flora and the lactobacilli infected.…”

Lactobacilli and human dental caries: more than mechanical retention

“…They are mostly thought to be transient in the mouth and their numbers on the tooth surfaces of healthy infants and young children are usually low [ 5, 6, 19 ]. Low affinity to the tooth surface is thought to be the major factor that contributes to its low prevalence in the plaque microbiota of healthy individuals [ 8, 10 ]. However, lactobacilli tend to increase in numbers with increasing intake of fermentable sugars in the diet, a situation that is also conducive to dental caries.…”

“…Recent studies by Caufield et al showed that about half of the L. fermentum analysed possesses the genes for the extracellular glucans, but they were remarkably absent in other species associated with severe childhood caries [ 5 ]. No evidence suggests that lactobacilli synthesize any major adhesive EPS from sucrose [ 8, 36 ] , which in S. mutans is predominantly α [3,1]-linked and known to play a central role in its adherence and cariogenicity [ 37 ].…”

“…Many of the Lactobacillus strains isolated from dental plaque, comprising different major species, were examined using animal models, including a gnotobiotic rat model, and were found to be moderately or highly cariogenic when the animals were fed with a diet rich in sucrose, but not when fed with glucose and/or starch [ 8, 9, 11, 65 ]. However, the level of carious lesions in animals infected with these lactobacilli strains was significantly lower, when compared to those infected with S. mutans [ 11 ].…”

“…It is well-known that the abilities to colonize and persist on the tooth surface, to catabolize sugars and produce weak acidic metabolites, and to tolerate the acids and the resulting low pH environment are traits considered essential for a bacterium to cause carious lesions [ 7 ]. Many studies using in vivo models, mostly prior to the mutans streptococci paradigm, have examined the roles of lactobacilli in dental caries [ 8–11 ], but questions remain inexplicit on the molecular mechanisms concerning how Lactobacillus sp. colonize and establish on the tooth surface and how they interact with the micro-environment and with other major bacterial species in the plaque microbiota, influencing the development including temporal structure and composition of the plaque microbiota.…”