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This study explored the inhibitory effect and mechanism of the culture supernatant of Lactiplantibacillus plantarum HB13-2 on Candida albicans. The minimum inhibitory concentration was determined by the double dilution method. Then, the fluorescent dye calcofluor white (CFW) was used to stain the cell wall and observe it. The results showed that the supernatant enhanced the fluorescence intensity and damaged the cell wall. Flow cytometry and fluorescence microscopy showed that the supernatant changed the membrane permeability of C. albicans. The transmembrane potential was detected using the fluorescent probe DiSC3(5), and it was found that the fluorescence intensity was enhanced, indicating that the supernatant caused dissipation of the transmembrane potential. Through microstructural observation by scanning electron microscopy (SEM), it was found that the supernatant of Lactobacillus plantarum HB13-2 caused cellular deformation and leakage of intracellular contents. As detected by fluorescence staining with 2’,7’-dichlorodihydrofluorescin diacetate (DCFH-DA) and Rhodamine-123, the supernatant resulted in accumulation of a large amount of intracellular reactive oxygen species (ROS) and increased mitochondrial membrane potential. In conclusion, the supernatant of L. plantarum HB13-2 can deform cells by destroying the cell wall and membrane and lead to mitochondrial damage, thereby inhibiting C. albicans. This study will provide a scientific basis for the development of L. plantarum HB13-2 as an oral probiotic.

The purpose of this study is to select lactic acid bacteria with a strong ability to inhibit oral pathogens, high safety and strong oral colonization capacity. Firstly, the strains that could inhibit Streptococcus mutans and Streptococcus gordonii were screened from lactic acid bacteria resource bank in the laboratory by Oxford cup diffusion method. The 28 selected strains were evaluated for hemolytic activity. The results showed that seven of the 28 strains showed α-hemolysis while the remaining 21 did not. The antibacterial metabolites of 16 strains without hemolysis and with a diameter of inhibition zone ≥ 10 mm against S. mutans and S. gordonii were determined by neutralization, catalase and protease susceptibility assays. Then seven strains with strong bacteriostatic capacity and the potential to produce non-organic acid antimicrobial metabolites were selected. The safety evaluation results showed that all seven strains had low acid production ability and caused low corrosion to teeth. The highest tolerable concentration of lysozyme for strain JZ14-1 was 1.6 mg/mL, while that for the other six strains was 1.2 mg/mL, indicating that all seven strains could tolerate lysozyme. Strain HB13-2 was most susceptible to antibiotics. The oral colonization capacity evaluation of strain HB13-2 showed the following results: the highest hydrophobicity of 44.00%, surface acid charge of 20.16%, surface base charge of 49.44%, and content of exopolysaccharides of 0.283 mg/mL. This strain could easily colonize in oral cavity and had low biofilm formation capacity and good self-aggregation capacity, and the maximum inhibition percentage against S. mutans biofilm was 59.72%. Moreover, strain HB13-2 had strong copolymerization capacity with S. mutans, and the copolymerization capacity was 67.40% at 24 h. In conclusion, strain HB13-2 has good antibacterial activity, high safety and strong oral colonization capacity. It is identified as Lactiplantibacillus plantarum by 16S rDNA sequencing.

• Inhibitory effect of PLA against the spores of Bacillus cereus were first reported. • Inactivation mechanism of PLA against germinated spores was proposed. • PLA was evidenced to exhibit preservative effect against spores in milk beverage. • This investigation could provide scientific basis for the application of PLA in food. Phenyllactic acid (PLA) as a natural phenolic acid exhibits antibacterial activity against non-spore-forming bacteria, while the inhibitory effect against bacterial spore remained unknown. Herein, this study investigated the inactivation effect of PLA against Bacillus cereus spores. The results revealed that the minimum inhibitory concentration of PLA was 1.25 mg/mL. PLA inhibited the outgrowth of germinated spores into vegetative cells rather than germination of spores. PLA disrupted the spore coat, and damaged the permeability and integrity of inner membrane. Moreover, PLA disturbed the establishment of membrane potential due to the inhibition of oxidative metabolism. SEM observations further visualized the morphological changes and structural disruption caused by PLA. Besides, PLA caused the degradation of DNA of germinated spores. Finally, PLA was applied in milk beverage, and showed promising inhibitory effect against B. cereus spores. This finding could provide scientific basis for the application of PLA against spore-forming bacteria in food industry. [ABSTRACT FROM AUTHOR]

Objective: To observe the characteristics of serum protein in patients with benign paroxysmal positional vertigo (BPPV) during the symptomatic period., Method: Fifty-five patients with BPPV and 58 control subjects were enrolled in the study. All the patients underwent the Dixe-Hallpike and Roll maneuver to confirm the type of BPPV. The average time of onset was (1.0 ± 0.8)days in the group of BPPV. The clinical features and the laboratory tests of serum protein electrophoresis, blood counts, and liver and kidney function were performed in both groups., Result: The levels of serum albumin (Alb), α1 globulin, α2 globulin and β globulin of BPPV group did not differ statistically in the two groups (P > 0.05); The γ-globulin levels were significantly higher in patients with BPPV than in controls (P < 0.05)., Conclusion: The γ-globulin levels are increased when BPPV is attacking.

Rare earth elements are wide-used in China, but a few of studies were made on whether they had toxicity to soil fauna. In this paper, the filter paper contact method was used to study the influence of two rare earth elements on the dynamics of amino acids in earthworm body. The result showed that at low concentrations, the test rare earth elements increased the amino acid contents except proline, but decreased them at high concentrations. The amino acid contents began to increase at 400 mg.L-1, while decreased with time. Both of the two rare earth elements reduced the proline content, and behaved inhibition effect at the range of 100-1,200 mg.L-1.