Detection of nitrite degradation by Lactobacillus plantarum DMDL9010 through the anaerobic respiration electron transport chain using proteomic analysis

Exploring the proteolytic activity of Lactiplantibacillus plantarum AHQ-14 to reduce the allergenicity of milk protein and its probiotic potential based on peptidomics and genomics

In our previous work, Lactiplantibacillus plantarum AHQ-14 was isolated from the conventional fermented dairy products in Xinjiang district (China) for its strong ability to reduce the antigenicity of bovine milk β-LG. Although its probiotic properties and safety were evaluated in vitro, it is necessary to further explore the effect of L. plantarum AHQ-14 on the major allergenic proteins and its mechanism of action and probiotic potential by peptidomics and genomics in this study. The results showed that the hydrolysis ability of L. plantarum AHQ-14 to α-LA, β-LG, and α-CN was the strongest at 10 h of incubation, and their IgE binding inhibition rates were also higher. Peptidomics results showed that L. plantarum AHQ-14 could destroy the main allergic epitopes of α-LA, β-LG, α-CN, and obtain a variety of bioactive peptides. Genomics results revealed L. plantarum AHQ-14 contained a great deal of genes encoding a phosphoenolpyruvate-dependent glucose phosphate transport system, a complete Opp oligopeptide transport system, and abundant peptidase-related genes, and indicated that L. plantarum AHQ-14 had a strong ability to metabolize and transport carbohydrates and AA, as well as strong hydrolyze proteins. Lactiplantibacillus plantarum AHQ-14 also had probiotic potential in pathogen defense and immune stimulation, and strong environmental adaptability. This study laid a foundation for the practical utilization of L. plantarum AHQ-14 and the further development of other probiotics with potential to reduce allergenicity of proteins.

Insights into the molecular mechanisms of lipid metabolism of air-dried goose on the formation of flavor substances by co-inoculation of lactic acid bacteria and staphylococcus based on GC-MS and lipidomics

Microorganisms and lipids always interact in a complex way in the meat matrix, which affects the flavor of meat products. This study aimed to examine the impact of complex fermentation with distinct microorganisms on fat oxidation, lipid profile, and the biochemical pathways involved in flavor substance formation. GC-MS analysis revealed that 12 key volatile substances including hexanal, heptanal, benzeneacetaldehyde, decanal, 1-nonanol, 1-hexanol, 1-octen-3-ol were responsible for the flavor variations in geese. Lipidomics analysis of three groups identified 440 lipid molecules, with triglycerides and glycerophospholipids being the most abundant categories. Spearman correlation analysis showed that 4 key volatile substances exhibited positive correlations with lysophosphatidylethanolamines, lysophosphatidycholines, phosphatidylcholines, phosphatidylethanolamines. The data presented herein facilitate an understanding of the lipid dynamics during fermentation and provide insights into the potential for controlling the flavor quality of fermented air-dried meat products.

Limosilactobacillus fermentum CGMCC 1.7434 and Debaryomyces hansenii GDMCC 2.149 synergize with ultrasound treatment to efficiently degrade nitrite in air-dried ducks

Nitrites in meat products are important food additives with coloring, antibacterial and antioxidant effects, but excessive intake of nitrites can pose health risks, including an increased risk of cancer due to the formation of carcinogenic nitrosamines. In the present study, Limosilactobacillus fermentum CGMCC 1.7434 was screened and the effects of it and Debaryomyces hansenii GDMCC 2.149 and their combination on nitrite degradation were investigated. It was found that the co-culture of L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 significantly enhanced nitrite degradation (99.58%). The findings on salt and ethanol tolerance suggest suitability for application in meat fermentation processes. Scanning electron microscopy and additional data indicate that D. hansenii GDMCC 2.149 facilitates the growth, acid production, adhesion, secretion of AI-2 signaling molecules, and biofilm formation of L. fermentum CGMCC 1.7434. Metabolomics analysis suggests that these microorganisms reduce nitrite levels by converting NH3 derived from nitrite into L-glutamine, which is further transformed into N-nitroso compounds and their downstream derivatives through the ABC transporter pathway, the TCA cycle, and the amino acid metabolism pathway. Microbial community analyses showed that L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 were successfully inoculated into air-dried ducks, becoming dominant strains and effectively inhibiting the growth of pathogenic bacteria. Furthermore, during the processing of air-dried duck, the combination of ultrasonic cavitation (250 W, 4 min, 30°C, 40 kHz) with the co-fermentation of L. fermentum CGMCC 1.7434 and D. hansenii GDMCC 2.149 effectively reduced nitrite content (84.55%) and TVB-N levels in the meat, without compromising color or TBARS values. This is crucial for understanding the mechanism of nitrite degradation by LAB in synergy with yeast and for the advancement of low-nitrite air-dried duck products.

Fermented Vegetables: Health Benefits, Defects, and Current Technological Solutions

This review summarizes current studies on fermented vegetables, analyzing the changes in nutritional components during pickling, the health benefits of fermented vegetables, and their safety concerns. Additionally, the review provides an overview of the applications of emergent non-thermal technologies for addressing these safety concerns during the production and processing of fermented vegetables. It was found that vitamin C would commonly be lost, the soluble protein would degrade into free amino acids, new nutrient compositions would be produced, and the flavor correlated with the chemical changes. These changes would be influenced by the variety/location of raw materials, the original bacterial population, starter cultures, fermentation conditions, seasoning additions, and post-fermentation processing. Consuming fermented vegetables benefits human health, including antibacterial effects, regulating intestinal bacterial populations, and promoting health (anti-cancer effects, anti-diabetes effects, and immune regulation). However, fermented vegetables have chemical and biological safety concerns, such as biogenic amines and the formation of nitrites, as well as the existence of pathogenic microorganisms. To reduce hazardous components and control the quality of fermented vegetables, unique starter cultures, high pressure, ultrasound, cold plasma, photodynamic, and other technologies can be used to solve these problems.

Transcriptomic Responses to Nitrite Degradation by Limosilactobacillus fermentum RC4 and Effect of ndh Gene Overexpression on Nitrite Degradation

The excessive nitrite residue may increase cell damage and cancer risk. Limosilactobacillu fermentum RC4 exhibited excellent nitrite degradation ability. Herein, the molecular mechanism of nitrite degradation by L. fermentum RC4 was studied by integrating scanning electron microscopy analysis, transcriptomics, and gene overexpression. The results demonstrated that the gene profile of RC4 cultured in MRS broth with 0, 100, and 300 mg/L NaNO2 varied considerably; RC4 responded to nitrite degradation by regulating pyruvate metabolism, energy synthesis, nitrite metabolism, redox equilibrium, protein protection, and signaling. High nitrite concentrations affected the morphology of RC4 with a longer phenotype, rough and wrinkle cell and reduced cell surface hydrophobicity. Moreover, an up-regulated expression of gene ndh encoding NADH dehydrogenase, which provides electrons for nitrite reduction by catalyzing NADH, was identified when RC4 was exposed to nitrite. Overexpression of ndh in RC4 increased the nitrite degradation rate by 2-9.5% in MRS broth with 100 mg/L NaNO2. Thus, the findings of this study could be helpful for the application of L. fermentum to reduce nitrite residues and improve food safety in fermented food products.

Research Update on the Impact of Lactic Acid Bacteria on the Substance Metabolism, Flavor, and Quality Characteristics of Fermented Meat Products

This paper reviews the effects of domestic and foreign influences on the substance metabolism pathways and the flavor and flora of LAB in fermented meat products to provide a new theoretical basis for developing new products for the industrial application of lactic acid bacteria (LAB) in fermented meat products. LAB are extensively used among commonly fermented ingredients, such as fermented meat products and yogurt. As fermenting agents, LAB metabolize proteins, lipids, and glycogen in meat products through their enzyme system, which affects the tricarboxylic acid cycle, fatty acid metabolism, amino acid decomposition, and other metabolic processes, and decompose biological macromolecules into small molecules, adding a special flavor with a certain functionality to the final product. Metabolites of LAB in the fermentation process also exert nitrite degradation, as well as antibacterial and antioxidant functions, which improve the physical and chemical qualities of fermented meat products. While fermenting meat products, LAB not only add unique flavor substances to the products, but also improve the safety profile of fermented foods.

Lactiplantibacillus plantarum DMDL 9010 alleviates dextran sodium sulfate (DSS)-induced colitis and behavioral disorders by facilitating microbiota-gut-brain axis balance

Previous studies have found that probiotic supplements can ameliorate mental behavioral disorders. This study investigated the effects of Lactiplantibacillus plantarum DMDL 9010 (LP9010) intake on the depression-like behavior induced by dextran sodium sulfate (DSS) and its possible mechanism. Male C57BL/6N mice were fed with DSS to establish the model of ulcerative colitis. LP9010 intake reduced the DSS-induced inflammatory response, and repaired intestinal barrier damage, as well as lightened depression-like behavior. LP9010 supplementation also inhibited neuroinflammation by up-regulating the levels of neurotransmitters, especially 5-HT, NE, DA, and 5-HIAA. Moreover, the intake of LP9010 reorganized the gut microbiome by increasing the relative abundance of Bacteroidetes and Firmicutes, and decreasing the relative abundance of Proteobacteria and Verrucomicrobia. Furthermore, treatment with LP9010 increased the levels of short-chain fatty acids, such as butyric acid and propionic acid. In conclusion, LP9010 intake was a promising probiotic intervention strategy for the prevention of colitis-induced behavioral disorders through the microbiota-gut-brain axis.