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To explore the key antibiofilm components of green Sichuan pepper essential oil (GPEO) against the spoilage microorganism Bacillus amyloliquefaciens and their intracellular targets, a molecular structure database of GPEO components and a collection of the molecule structures of target proteins related to the biofilm formation of B. amyloliquefaciens were created based on related literature data, and the CB-DOCK2 servicer was used to perform molecular docking of the active components of GPEO to biofilm formation-related target proteins. Furthermore, the key antibiofilm components of GPEO were selected based on their docking affinity and their potential targets were explored. Finally, in vitro experiments and crystal violet staining were conducted to confirm the antibiofilm effects of two key active components of GPEO, caryophyllene oxide and β-caryophyllene, against B. amyloliquefaciens. Molecular docking results showed that 24 volatile components of GPEO had different affinities to 58 targets associated with the biofilm formation of B. amyloliquefaciens, among which β-caryophyllene and caryophyllene oxide could tightly bind to ComP and RapC through intermolecular forces such as hyperconjugation, hydrophobic interaction and van der Waals force, forming a stable conformation. In vitro experiments showed that the minimal inhibitory concentrations (MICs) of caryophyllene oxide and β-caryophyllene against the biofilm of B. amyloliquefaciens were 6.0 and 2.0 mg/mL, respectively. Both compounds interfered with the swimming motility of this bacterium, reduced the initial cell adhesion and auto-aggregation ability, and altered the cell surface hydrophobicity. These results provide feasible strategies to help decipher the intracellular molecular mechanisms related to the biological activity of plant essential oil.

In vegetable fermentation, pellicle is a common quality deterioration phenomenon. This study investigates the characteristics of glucose, organic acids, amino acids, and biogenic amines during the pellicle occurrence and disappearance of paocai. The results revealed a slight increase in pH of the fermentation system after pellicle occurred, and glucose was the main carbohydrate that microbial activity primary relied on. The microorganisms responsible for pellicle formation consumed organic acids in brine, but the lactic acid in paocai gradually increased and exceeded 25 mg/g. The appearance of pellicle caused a decrease in total free amino acids from 200.390 mg/100 g to 172.079 when pellicle occurred, whereas its impact on biogenic amines was not apparent. Through Kyoto Encyclopedia of Genes and Genomes pathway enrichment of metagenomics sequencing data, screening, and sorting of the key enzymes involved in organic acid metabolism, it was observed that the composition and species of the key microorganisms capable of metabolizing organic acids were more abundant before the appearance of pellicle. When pellicle occurred, lactic acid may be metabolized by Lactobacillus plantarum; in contrast, Lactobacillus and Pichia were associated with citric acid metabolism, and Lactobacillus, Pichia, Saccharomycodes, and Kazachstania were linked to malic acid metabolism. Moreover, Prevotella, Kazachstania, Lactobacillus, Vibrio, and Siphonobacter were implicated in succinic acid metabolism. Additionally, the production of tartaric acid and oxalic acid in paocai and brine resulted from abiotic effects. This knowledge offers a theoretical basis for precise control of paocai fermentation process. Practical Application: Our study revealed the specific situation of the metabolites produced by the microorganisms during the pollution and recovery process of pellicle in paocai fermentation, especially the effect of pellicle on the key process of organic acid metabolism. These research results provided theoretical basis for precise control of paocai fermentation. [ABSTRACT FROM AUTHOR]

Pectin is a complex polysaccharide found in plant cell walls and interlayers. As a food component, pectin is benefit for regulating intestinal flora. Metabolites of intestinal flora, including short-chain fatty acids (SCFAs), bile acids (BAs) and lipopolysaccharides (LPS), are involved in blood glucose regulation. SCFAs promote insulin synthesis through the intestine-GPCRs-derived pathway and hepatic adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathway to promote hepatic glycogen synthesis. On the one hand, BAs stimulate intestinal L cells and pancreatic α cells to secrete Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) through receptors G protein-coupled receptor (TGR5) and farnesoid X receptor (FXR). On the other hand, BAs promote hepatic glycogen synthesis through AMPK pathway. LPS inhibits the release of inflammatory cytokines through Toll-like receptors (TLRs)-myeloid differentiation factor 88 (MYD88) pathway and mitogen-activated protein kinase (MAPK) pathway, thereby alleviating insulin resistance (IR). In brief, both SCFAs and BAs promote GLP-1 secretion through different pathways, employing strategies of increasing glucose consumption and decreasing glucose production to maintain normal glucose levels. Notably, pectin can also directly inhibit the release of inflammatory cytokines through the -TLRs-MYD88 pathway. These data provide valuable information for further elucidating the relationship between pectin-intestinal flora-glucose metabolism. [ABSTRACT FROM AUTHOR]

The objective of this study was to screen lactic acid bacteria strains with high exopolysaccharides production potential from sugar beet molasses. The taxonomic identification and growth characteristics of a lactic acid bacteria strain M1 with high exopolysaccharides-producing capacity isolated from sugar beet molasses were investigated. Furthermore, the exopolysaccharides fermentation parameters using sugar beet molasses as an alternative carbon source to sucrose were optimized using a single-factor experiment and response surface methodology based on Box-Behnken design. Moreover, antioxidant activity of the harvested crude exopolysaccharides were evaluated. The results showed that strain M1 was taxonomically classified as Leuconostoc suionicum. The growth profile of L. suionicum M1 indicated a lag phase of 2 hours, an optimal temperature of 35 °C, a favorable pH value of 8. 0, and a remarkable tolerance to sucrose concentrations up to 60%. The optimal medium for exopolysaccharides production consisted of 300 g/L sugar beet molasses, 20. 0 g/L yeast extract, 15. 0 g/L K2HPO4·3H2O, 0. 2 g/L MgSO4·7H2O, 0. 01 g/L NaCl, 0. 01 g/L CaCl2·2H2O, 0. 01 g/L MnSO4·4H2O, 0. 01 g/L FeSO4·7H2O. The maximum exopolysaccharides yield of 39. 1 g/L was achieved under the following conditions: loading volume 200 mL/250 mL, inoculum size 5%, initial pH value 8. 1, fermentation temperature of 38. 5 °C and fermentation period 41. 1 h. The exopolysaccharides produced by strain M1 exhibited significant antioxidant activities, with quenching capacities of 70. 25% for DPPH radicals, 47. 16% for ·OH radicals, 35. 92% for ABTS+ radicals and 0. 42 for Fe3+ total reducing force at a concentration of 6. 0 mg/ mL. Strain M1 was capable of producing exopolysaccharides with antioxidant activity using sugar beet molasses, and could be used as a promising candidate for the bioconversion of sugar beet molasses into functional exopolysaccharides products. [ABSTRACT FROM AUTHOR]