PROBLEM TO BE SOLVED: To provide a lactobacillus useful for prevention of caries, prevention/treatment of periodontal disease, improvement/prevention of foul breath, and suppression of biofilm formation in the oral cavity at ordinary times (at times other than during eating), or a culture and a culture supernatant of this lactobacillus, their neutralized products, a composition containing these, and the like.SOLUTION: A lactobacillus is one selected from strains of Lactobacillus paracasei, Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus sakei, Enterococcus avium, and Enterococcus durans. The lactobacillus has a property of suppressing growth of the above intraoral bacterium and/or formation of a biofilm formed by the above intraoral bacterium, in co-cultivation in a sugar-free medium with an intraoral bacterium causing caries, periodontal diseases or foul breath.
