Lacticaseibacillus paracasei completely utilizes fructooligosacchrides in the human gut through ß-fructosidase (FosE).

The fecal microbiota of two healthy adults was cultivated in a medium containing commercial fructooligosaccharides [FOS; 1-kestose (GF2), nystose (GF3), and 1F-fructofuranosylnystose (GF4)]. Initially, the proportions of lactobacilli in the two feces samples were only 0.42% and 0.17%; however, they significantly increased to 7.2% and 4.8%, respectively, after cultivation on FOS. Most FOS-utilizing isolates could utilize only GF2; however, Lacticaseibacillus paracasei strain Lp02 could fully consume GF3 and GF4 too. The FOS operon (fosRABCDXE) was present in Lc. paracasei Lp02 and another Lc. paracasei strain, KCTC 3510T, but fosE was only partially present in the non-FOS-degrading strain KCTC 3510T. In addition, the top six upregulated genes in the presence of FOS were fosABCDXE, particularly fosE. FosE is a ß-fructosidase that hydrolyzes both sucrose and all three FOS. Finally, a genome-based analysis suggested that fosE is mainly observed in Lc. paracasei, and only 13.5% (61/452) of their reported genomes were confirmed to include it. In conclusion, FosE allows the utilization of FOS, including GF3 and GF4 as well as GF2, by some Lc. paracasei strains, suggesting that this species plays a pivotal role in FOS utilization in the human gut.

Development of nationally representative exposure factor database for children's products in Korea.

BACKGROUND: Children may be exposed to harmful chemicals from their products. Accurate exposure factors are critical for exposure assessment of children's products. Product usage pattern parameters are relatively limited compared with the chemical concentration, children's physiological and behavioral parameters. OBJECTIVE: The aim of this study was to determine nationally representative Korean exposure factors for the usage patterns of children's products by sex, age, and season. METHODS: Using proportional quota sampling, a survey of 10,000 households with children aged 0-12 years was conducted twice, once in summer and winter. The children's ages were divided into four groups: infant (0-2 years old), toddler (3-6), lower-grade elementary student (7-9), and higher-grade elementary student (10-12). Data on exposure factors such as use rate, use frequency, and use duration of 57 children's products were collected. RESULTS: The 57 products were classified into five categories: baby products (13), toys (12), daily products (10), sporting goods (8), and stationery (14). The use rates of products in the daily products and stationery category were >90% in both seasons. Two of the 57 products showed significant sex differences in all three exposure factors (p < 0.001). Twenty-five of the 44 non-baby products showed significant age differences for all three exposure factors. Twenty-three of the 57 products varied significantly with season for all three exposure factors. IMPACT: This study generated a nationally representative exposure factor database for the usage patterns of children's products in Korea. The exposure factors for 57 children's products were investigated through twice survey with quota sampling with each 10,000 children nationwide. Sex, age, and seasonal differences for children's products were identified. These accurate exposure factors by sex, age, and season can be used as input parameters for refined exposure assessment.