The invention relates to the technical field of microorganisms, in particular to a viable bacterium preparation of a
lactobacillus paracasei strain as well as a preparation method and application of the viable bacterium preparation. The viable bacterium preparation comprises a
lactobacillus paracasei strain and auxiliary materials, and the preservation number of the
lactobacillus paracasei strain is CGMCC (China General
Microbiological Culture Collection Center) No.27974. The viable bacterium preparation can inhibit the growth of
streptococcus mutans, reduce the formation of a
dental plaque biofilm caused by the
streptococcus mutans, reduce the content of a mature
dental plaque biofilm, inhibit the level of water-insoluble exopolysaccharides generated by the
streptococcus mutans, reduce the expression quantity of cariogenic genes gtfB, gtfC, gtfD, ftf and LuxS of the
streptococcus mutans, improve the cariogenic activity of the
streptococcus mutans and improve the cariogenic activity of the
streptococcus mutans. The adhesion rate of streptococcus mutans on a hydroxyapatite tooth model is reduced, and a beneficial in-vitro
probiotic function is achieved.