Huichun Tong

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The oral microbial flora contains over 500 different microbial species that often interact as a means to compete for limited space and nutritional resources. Streptococcus mutans, a major caries-causing pathogen, is a species which tends to interact competitively with other species in the oral cavity, largely due to its ability to generate copious(More)
Complex interspecies interactions occur constantly between oral commensals and the opportunistic pathogen Streptococcus mutans in dental plaque. Previously, we showed that oral commensal Streptococcus oligofermentans possesses multiple enzymes for H(2)O(2) production, especially lactate oxidase (Lox), allowing it to out-compete S. mutans. In this study,(More)
Two novel Pediococcus strains, Z-1 and Z-8(T), were isolated from a distilled-spirit-fermenting cellar in Hebei Province, China. The cells were Gram-positive, non-spore-forming, non-motile cocci, occurring in pairs or tetrads. The strains were facultatively anaerobic and produced 50 % (-)-D-/50% (+)-L-lactic acid exclusively from glucose fermentation, but(More)
We previously demonstrated that Streptococcus oligofermentans suppressed the growth of Streptococcus mutans, the primary cariogenic pathogen, by producing hydrogen peroxide (H(2)O(2)) through lactate oxidase activity. In this study, we found that the lox mutant of S. oligofermentans regained the inhibition while growing on peptone-rich plates. Further(More)
Two novel Pediococcus strains, Z-9(T) and Z-17, were isolated from a distilled-spirit-fermenting cellar in Hebei Province, China. The cells were Gram-positive, non-spore-forming, non-motile cocci and occurred in pairs or tetrads. The strains were facultatively anaerobic and produced only lactic acid [d(-) and l(+) isomers in the ratio 50 : 50] from glucose(More)
Five streptococcal strains were isolated from dental plaque and saliva of caries-free humans. The cells were gram-positive, non-spore-forming, non-motile cocci that were arranged in short chains. The strains were catalase-negative, facultatively anaerobic and produced lactic acid exclusively from glucose fermentation. Biochemical analysis that used both(More)
Homeostasis of oral microbiota can be maintained through microbial interactions. Previous studies showed that Streptococcus oligofermentans, a non-mutans streptococci frequently isolated from caries-free subjects, inhibited the cariogenic Streptococcus mutans by the production of hydrogen peroxide (HP). Since pH is a critical factor in caries formation, we(More)
Commensal oral streptococci play critical roles in oral biofilm formation and promote dental health by competing with, and antagonizing the growth of, pathogenic organisms, such as Streptococcus mutans. Efficient utilization of the spectrum of carbohydrates in the oral cavity by commensal streptococci is essential for their persistence, and yet very little(More)
Streptococcus oligofermentans is a newly characterized species belonging to the mitis group of oral streptococci. So far no correlation has been demonstrated between S. oligofermentans and dental caries. Furthermore, a reverse correlation has been observed between the number of S. oligofermentans and the number of Streptococcus mutans, a major cariogenic(More)
Streptococcus oligofermentans is an oral commensal that inhibits the growth of the caries pathogen Streptococcus mutans by producing copious amounts of H(2)O(2) and that grows faster than S. mutans on galactose. In this study, we identified a novel eight-gene galactose (gal) operon in S. oligofermentans that was comprised of lacABCD, lacX, and three genes(More)