Previous studies have demonstrated that the presence of lactic acid bacteria (LAB), especially those classified into the genus Lactobacillus, is associated with the progression of dental caries in preschool children. Nevertheless, the kinds of species of LAB and the characteristics that are important for dental caries have been unclear. The aims of this study were: (1) to investigate the distribution of oral LAB among Japanese preschool children with various prevalence levels of caries; and (2) to reveal the characteristics of these isolated LAB species. Seventy-four Japanese preschool children were examined for caries scores and caries progression, and their dental cavity samples were collected for LAB isolation and identification. The saliva-induced agglutination rate and the resistance to acidic environments of the identified strains were measured. Statistical analysis showed that preschool children carrying Lactobacillus (L.) salivarius or Streptococcus mutans have a significantly higher prevalence of dental caries, the growth ability in acidic environments correlates with the caries scores of individuals with L. salivarius, and the caries scores exhibit positive correlation with saliva-induced agglutination in L. salivarius. These results show that specific Lactobacillus species are associated with dental caries based on the level of carious lesion severity. The present study suggests that these specific Lactobacillus species, especially those with easily agglutinated properties and acid resistance, affect the dental caries scores of preschool children, and that these properties may provide useful information for research into the prevention of dental caries.

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The aim of this study was to investigate whether consumption of probiotic fermented milk containing Bifidobacterium bifidum YIT 10347 improves symptoms in patients with functional gastrointestinal disorders (FGID). Thirty-seven FGID patients (18 male, 19 female) aged 12–80 years (mean ± SD, 52.6 ± 17.5 years) whose condition had not improved despite being seen at several medical institutions consumed 100 mL/day of B. bifidum YIT 10347 fermented milk for 4 weeks. Symptoms were evaluated after the enrollment period (BL: baseline), sample consumption period (CP) and 4 weeks after the CP (FP: follow-up period). Gastrointestinal symptoms were evaluated using the Gastrointestinal Symptom Rating Scale (GSRS) and the Frequency Scale for the Symptoms of Gastroesophageal Reflux Disease (FSSG); psychological symptoms were evaluated using the Profile of Mood States (POMS) short form. Concentrations of salivary stress markers and the oxidative stress marker urinary 8-hydroxy-2’-deoxyguanosine (8-OHdG) were measured. GSRS subscale scores for abdominal pain, diarrhea, and constipation significantly improved relative to BL after consumption of the fermented milk, as did FSSG subscale scores for symptoms of acid-related dyspepsia. Some subjective psychological symptoms improved. POMS scores significantly improved, and “Anger-Hostility” subscale scores significantly decreased after the consumption period, while “Vigor” subscale scores marginally increased during the consumption period. The concentrations of urinary 8-OHdG and the stress marker salivary cortisol were significantly lower at CP but returned to baseline levels at FP. Continuous consumption of B. bifidum YIT 10347 fermented milk is expected to improve gastrointestinal symptoms and reduce psychological stress in FGID patients.

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A bacterial community analysis, using a culture-independent method (polymerase chain reaction-denaturing gradient gel electrophoresis), detected 17 species of bacteria including species of the genera Tetragenococcus, Lactobacillus, Pediococcus, Weissella Halanaerobium, Clostridium, and Sphingomonas in a traditional salty-fermented fish paste known as pla-ra or pa-daek in Thailand and Laos, which is used as a storage-stable multi-purpose seasoning. The representative genus of lactic acid bacteria seemed to vary in the 10 products collected from Thailand and Laos. Tetragenococci were common in products from central Thailand and Vientiane in Laos which had salinities of not less than 11% and pH values ranging from 5.6 to 6.1. However, lactobacilli were common in products from northern Thailand which had the lowest salinities (8.3–8.6%) and pH values (4.5–4.8) of all the samples examined. Two Lactobacillus and one Tetragenococcus species were detected in one product from northeastern Thailand containing 10% salt. These results suggest that salinity in pla-ra/pa-daek is an important determinant of the representative genus of lactic acid bacteria such as, Tetragenococcus or Lactobacillus. Additionally, differences in the acidity between these two groups seemed to be related to the production of d-/l-lactic acid in the lactic acid bacteria in each product. This is the first study to report a correlation between bacterial community structure and taste components in pla-ra/pa-daek products from various regions. This scientific work on a traditional fermented food will be useful in helping local producers meet differing consumer preferences in various regions.

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