Probiotics can prevent obesity and related metabolic complications. In our study, the protective effect and molecular mechanism of Lactobacillus rhamnosus JL1 (separated from the feces of healthy infants) on high-fat diet mice were investigated. After 10 weeks of dietary intervention with L. rhamnosus JL1 intervention, the body weight of the JL1 group (23.78 g) was significantly lower than that of the HFD group (26.59 g, p < 0.05) and the liver index was reduced. Serum biochemical analysis showed that the TC, TG and LDL-C contents of JL1 group mice were significantly decreased (p < 0.05). Histological images of the mice livers showed that the degree of lipid action and damage of hepatic cells were improved. L. rhamnosus JL1 activated the AMPK pathway, and reduced the gene expression of PPAR-γ, LXR-α and SREBP-1C. In addition, the protein expression of PPAR-γ and LXR-α were reduced. After dietary intervention with L. rhamnosus JL1, the concentration of acetic acid, propionic acid, and butyric acid were increased significantly, especially the concentration of butyric acid, which was 63.16% higher than that of the HFD group (p < 0.05). In conclusion, this study provided a theoretical reference for the development and application of probiotics derived from healthy infant feces in health products and functional foods.
Salmonella typhimurium (S. typhimurium) is a foodborne pathogen that has caused numerous outbreaks worldwide, necessitating the development of on-site strategy to prevent early contamination. Here, we set up an enzyme-free strategy for aptamer-catalyzed hairpin assembly in which salt-induced aggregation of unmodified gold nanoparticles (AuNPs) served as a colorimetric signal output, allowing on-site detection of S. typhimurium in milk. The aptamer-functionalized magnetic beads were used as a vehicle of specifically enriching target bacteria which conjugated with target aptamer to trigger the “Y” shape catalytic hairpin assembly (Y-CHA) circuit. Due to the hairpins desorbing from the surface of AuNPs to the formation of a large amount of double-stranded DNA (dsDNA), AuNPs turned from dispersion to aggregation in the presence of S. typhimurium, resulting in a change of the colorimetric signal from red to blue-gray. The signal output showed a linear relationship for S. typhimurium over a concentration range of 102 to 106 CFU/mL, with a sensitivity of 2.4 × 102 CFU/mL under optimal conditions. The visual protocol has excellent selectivity even in the presence of other competitive bacteria and has been validated in real milk samples with a sensitivity of 2.8 × 103 CFU/mL.
Escherichia coli O157:H7 is an extremely serious foodborne pathogen accounting for a vast number of hospitalizations. In this system, a simple, rapid, and safe compound method was developed based on carbonyl iron powder (CIP) and multiwalled carbon nanotubes (MWCNT). Then, the CIP@ MWCNT -based aptasensor was constructed by strong π-stacking between nanocomposite and aptamer, single-strand DNA, causing fluorescent quenching of the dye-labeled aptamer. The restoration of dye fluorescence could be achieved when aptamer came off the surface of the CIP@ MWCNT nanocomposite due to the presence of target bacteria. To the best of our knowledge, this fabrication of magnetic carbon nanotubes without irritating and corrosive reagents is described for the first time. The sensing platform was also an improvement on the conventional formation of the aptasensor between carbon materials and DNA aptamer. The nanocomposite was verified by diverse characterization of zeta potential, Fourier-transform infrared spectroscopy, transmission electron microscopy, and energy dispersive x-ray analysis. The CIP@ MWCNT -based aptasensor was an effective nanoplatform for quantitative detection of E. coli O157:H7, and was measured to have high specificity, good reproducibility, and strong stability. The aptasensor's capacity to quantify E. coli O157:H7 was as low as 7.15 × 10 3 cfu/mL in pure culture. The detection limit of E. coli O157:H7 was 3.15 × 10 2 cfu/ mL in contaminated milk after 1 h of pre-incubation. Hence, the developed assay is a new possibility for effective synthesis of nanocomposites and sensitive tests of foodborne pathogens in the dairy industry.
High-glucose-fat diet-induced glucolipid metabolism disorder has become a global epidemic disease. Probiotic intervention is a new strategy to alleviate metabolic syndrome. The protective effect and mechanism of L. paracasei JY062 on high-glucose-fat diets mice were investigated. After 7 weeks L. paracasei JY062 intervention, the body weight of mice in the LPH group (28.07 ± 1.07 g) was significantly lower than that of HFD group (32.03 ± 0.89 g) (P < 0.05). Among three doses of JY062, 108 and 109 CFU/mL JY062 showed the strong ability to relieve blood glucose disorders, blood lipid disorders, tissue damage. LPH group had the best effect, significantly (P < 0.05) decreased the TC (40.11%), TG (42.46%), LDL-C (39.38%), leptin (54.34%), insulin (39.95%), FFA (40.68%) concentrations and increased (P < 0.05) the HDL-C (1.05 times), adiponectin (1.53 times) and GLP-1 (1.35 times) level compared to HFD group mice. JY062 could activate the APN-AMPK pathway, increase AdipoQ, AMPK GLUT-4 and PGC-1αmRNA expression, and decrease SREBP-1c, ACC and FAS mRNA expression. L. paracasei JY062 intervention decreased the relative abundance of harmful bacteria and increased the relative abundance of beneficial bacteria, restored the imbalance of gut microbiota homeostasis caused by high-glucose-fat diet. L. paracasei JY062 could also increase the content of SCFAs in the intestines, especially butyric acid.
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