Glutathione Utilization in Lactobacillus fermentum CECT 5716

Methionine affects the freeze-drying resistance of Lactiplantibacillus plantarum LIP-1 by improving its antioxidant capacity

BACKGROUND

Lactic acid bacteria is an essential industrial strain, and improving its freeze-drying survival rate is the key challenge to ensuring the activity and stability of bacterial powder. Although medium optimization has been shown to strengthen strain freeze-drying tolerance, the mechanism by which amino acids repair freeze-drying damage in lactic acid bacteria remains unclear. This study investigated the effects of methionine on the freeze-drying survival rate of Lactiplantibacillus plantarum LIP-1 and explored the underlying protective mechanisms.

RESULTS

The study demonstrates that supplementing the medium with 0.06 g/L methionine significantly improved the freeze-drying survival rate of Lactiplantibacillus plantarum LIP-1 (P < 0.05). Further analysis revealed that the strain significantly reduced intracellular reactive oxygen species levels through metabolizing methionine (P < 0.05), decreased the oxidation degree of unsaturated fatty acids in the cell membrane, and reduced cell membrane damage, thereby strengthening the freeze-drying resistance of the strain.

CONCLUSION

Methionine can enhance the freeze-drying resistance of Lactiplantibacillus plantarum LIP-1 by enhancing antioxidant capacity and maintaining the stability of the subcellular structure. This study provides a specific reference value for improving the freeze-drying survival rate of lactic acid bacteria by modifying the medium conditions. © 2025 Society of Chemical Industry.

Proteomic Analysis of Milk Fat Globule Membrane Protein Modulation of Differently Expressed Proteins in Lactobacillus plantarum under Bile Salt Stress

Tolerance to bile stress is a crucial property for lactic acid bacteria (LAB) to survive in the gastrointestinal tract and exert their beneficial effects. Whey powder enriched with milk fat globule membrane proteins (M-WPI) as a functional component is protective for strains under stress conditions. The current study investigated the key mechanisms of action involved in Lactobacillus plantarum (L. plantarum) CGMCC 23701 survival in the presence of bile and the protective mechanism of M-WPI. According to proteomic analysis (proteomics), there could be several reasons for the greater protective effect of M-WPI. These include promoting the synthesis of fatty acids and peptidoglycans to repair the structure of the cell surface, regulating the metabolism of carbohydrates and amino acids to release energy and produce a range of precursors, enabling the expression of the repair system to repair damaged DNA, and promoting the expression of proteins associated with the multidrug efflux pump, which facilitates the exocytosis of intracellular bile salts. This study helps us to better understand the changes in proteome of L. plantarum CGMCC 23701 under bile salt stress and M-WPI protection, which will provide a new method for the protection and development of functional LAB.

Halophilic lactic acid bacteria - Play a vital role in the fermented food industry

Halophilic lactic acid bacteria have been widely found in various high-salt fermented foods. The distribution of these species in salt-fermented foods contributes significantly to the development of the product's flavor. Besides, these bacteria also have the ability to biosynthesize bioactive components which potentially apply to different areas. In this review, insights into the metabolic properties, salt stress responses, and potential applications of these bacteria have been have been elucidated. The purpose of this review highlights the important role of halophilic lactic acid bacteria in improving the quality and safety of salt-fermented products and explores the potential application of these bacteria.

An Overview of the Use and Applications of Limosilactobacillus fermentum in Broiler Chickens

The implementation of government regulations on antibiotic use, along with the public's concern for drug resistance, has strengthened interest in developing alternatives not only aimed at preserving animal production but also at reducing the effects of pathogenic infections. Probiotics, in particular, are considered microorganisms that induce health benefits in the host after consumption of adequate amounts; they have been established as a potential strategy for improving growth, especially by stimulating intestinal homeostasis. Probiotics are commonly associated with lactic acid bacteria, and Limosilactobacillus fermentum is a well-studied species recognized for its favorable characteristics, including adhesion to epithelial cells, production of antimicrobial compounds, and activation of receptors that prompt the transcription of immune-associated genes. Recently, this species has been used in animal production. Different studies have shown that the application of L. fermentum strains not only improves the intestinal ecosystem but also reduces the effects caused by potentially pathogenic microorganisms. These studies have also revealed key insights into the mechanisms behind the actions exerted by this probiotic. In this manuscript, we aim to provide a concise overview of the effects of L. fermentum administration on broiler chicken health and performance.

Metabolism of hydrogen peroxide by Lactobacillus plantarum NJAU-01: A proteomics study

This study aimed to investigate the time-course effect of Lactobacillus plantarum NJAU-01 in scavenging exogenous hydrogen peroxide (H₂O₂). The results showed that L. plantarum NJAU-01 at 10⁷ CFU/mL was able to eliminate a maximum of 4 mM H₂O₂ within a prolonged lag phase and resume to proliferate during the following culture. Redox state in the start-lag phase (0 h, without the addition of H₂O₂), indicated by glutathione and protein sulfhydryl, was impaired in the lag phase (3 h and 12 h) and then gradually recovered during subsequent growing stages (20 h and 30 h). By using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and proteomics analysis, a total of 163 proteins such as PhoP family transcriptional regulator, glutamine synthetase, peptide methionine sulfoxide reductase, thioredoxin reductase, ribosomal proteins, acetolactate synthase, ATP binding subunit ClpX, phosphoglycerate kinase, UvrABC system protein A and UvrABC system protein B were identified as differential proteins across the entire growth phase. Those proteins were mainly involved in H₂O₂ sensing, protein synthesis, repairing proteins and DNA lesions, amino sugar and nucleotide sugar metabolism. Our data suggest that biomolecules of L. plantarum NJAU-01 are oxidized to passively consume H₂O₂ and are restored by the enhanced protein and/or gene repair systems.

Limosilactobacillus fermentum CECT5716: Clinical Potential of a Probiotic Strain Isolated from Human Milk

Breastfeeding provides the ideal nutrition for infants. Human milk contains a plethora of functional ingredients which foster the development of the immune system. The human milk microbiota predominantly contributes to this protective effect. This is mediated by various mechanisms, such as an antimicrobial effect, pathogen exclusion and barrier integrity, beneficial effects on the gastrointestinal microbiota, vitamin synthesis, immunity enhancement, secreted probiotic factors, and postbiotic mechanisms. Therefore, human milk is a good source for isolating probiotics for infants who cannot be exclusively breastfed. One such probiotic which was isolated from human milk is Limosilactobacillus fermentum CECT5716. In this review, we give an overview of available interventional studies using Limosilactobacillus fermentum CECT5716 and summarise preclinical trials in several animal models of different pathologies, which have given first insights into its mechanisms of action. We present several randomised clinical studies, which have been conducted to investigate the clinical efficacy of the Limosilactobacillus fermentum CECT5716 strain in supporting the host's health.

The effect of glutathione biosynthesis of Streptococcus thermophilus ST-1 on cocultured Lactobacillus delbrueckii ssp. bulgaricus ATCC11842

Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus are the main species used for yogurt preparation. Glutathione (GSH) can be synthesized by S. thermophilus and plays a crucial role in combating environmental stress. However, the effect of GSH biosynthesis by S. thermophilus on cocultured L. delbrueckii ssp. bulgaricus is still unknown. In this study, a mutant S. thermophilus ΔgshF was constructed by deleting the GSH synthase. The wild strain S. thermophilus ST-1 and ΔgshF mutants were cocultured with L. delbrueckii ssp. bulgaricus ATCC11842 by using Transwell chambers (Guangzhou Shuopu Biotechnology Co., Ltd.), respectively. It was proven that the GSH synthesized by S. thermophilus ST-1 could be absorbed and used by L. delbrueckii ssp. bulgaricus ATCC11842, and promote growth ability and stress tolerance of L. delbrueckii ssp. bulgaricus ATCC11842. The biomass of L. delbrueckii ssp. bulgaricus ATCC11842 cocultured with S. thermophilus ST-1 or ΔgshF (adding exogenous GSH) increased by 1.8 and 1.4 times compared with the biomass of L. delbrueckii ssp. bulgaricus ATCC11842 cocultured with S. thermophilus ΔgshF. Meanwhile, after H₂O₂ and low-temperature treatments, the bacterial viability of L. delbrueckii ssp. bulgaricus cocultured with S. thermophilus ΔgshF, with or without GSH, was decreased by 41 and 15% compared with that of L. delbrueckii ssp. bulgaricus cocultured with S. thermophilus ST-1. Furthermore, transcriptome analysis showed that the expression levels of genes involved in purine nucleotide and pyrimidine nucleotide metabolism in L. delbrueckii ssp. bulgaricus ATCC11842 were at least 3 times increased when cocultured with S. thermophilus (fold change > 3.0). Moreover, compared with the mutant strain ΔgshF, the wild-type strain ST-1 could shorten the fermented curd time by 5.3 hours during yogurt preparation. These results indicated that the GSH synthesized by S. thermophilus during cocultivation effectively enhanced the activity of L. delbrueckii ssp. bulgaricus and significantly improved the quality of fermented milk.

Characterization of a highly conserved MUC5B-degrading protease, MdpL, from Limosilactobacillus fermentum

MUC5B is the predominant glycoprotein in saliva and is instrumental in the establishment and maintenance of multi-species eubiotic biofilms in the oral cavity. Investigations of the aciduric Lactobacillaceae family, and its role in biofilms emphasizes the diversity across different genera of the proteolytic systems involved in the nutritional utilization of mucins. We have characterized a protease from Limosilactobacillus fermentum, MdpL (Mucin degrading protease from Limosilactobacillus) with a high protein backbone similarity with commensals that exploit mucins for attachment and nutrition. MdpL was shown to be associated with the bacterial cell surface, in close proximity to MUC5B, which was sequentially degraded into low molecular weight fragments. Mapping the substrate preference revealed multiple hydrolytic sites of proteins with a high O-glycan occurrence, although hydrolysis was not dependent on the presence of O-glycans. However, since proteolysis of immunoglobulins was absent, and general protease activity was low, a preference for glycoproteins similar to MUC5B in terms of glycosylation and structure is suggested. MdpL preferentially hydrolyzed C-terminally located hydrophobic residues in peptides larger than 20 amino acids, which hinted at a limited sequence preference. To secure proper enzyme folding and optimal conditions for activity, L. fermentum incorporates a complex system that establishes a reducing environment. The importance of overall reducing conditions was confirmed by the activity boosting effect of the added reducing agents L-cysteine and DTT. High activity was retained in low to neutral pH 5.5-7.0, but the enzyme was completely inhibited in the presence of Zn²⁺. Here we have characterized a highly conserved mucin degrading protease from L. fermentum. MdpL, that together with the recently discovered O-glycanase and O-glycoprotease enzyme groups, increases our understanding of mucin degradation and complex biofilm dynamics.

The Therapeutic Role of Exercise and Probiotics in Stressful Brain Conditions

Oxidative stress has been recognized as a contributing factor in aging and in the progression of multiple neurological disorders such as Parkinson’s disease, Alzheimer’s dementia, ischemic stroke, and head and spinal cord injury. The increased production of reactive oxygen species (ROS) has been associated with mitochondrial dysfunction, altered metal homeostasis, and compromised brain antioxidant defence. All these changes have been reported to directly affect synaptic activity and neurotransmission in neurons, leading to cognitive dysfunction. In this context two non-invasive strategies could be employed in an attempt to improve the aforementioned stressful brain status. In this regard, it has been shown that exercise could increase the resistance against oxidative stress, thus providing enhanced neuroprotection. Indeed, there is evidence suggesting that regular physical exercise diminishes BBB permeability as it reinforces antioxidative capacity, reduces oxidative stress, and has anti-inflammatory effects. However, the differential effects of different types of exercise (aerobic exhausted exercise, anaerobic exercise, or the combination of both types) and the duration of physical activity will be also addressed in this review as likely determinants of therapeutic efficacy. The second proposed strategy is related to the use of probiotics, which can also reduce some biomarkers of oxidative stress and inflammatory cytokines, although their underlying mechanisms of action remain unclear. Moreover, various probiotics produce neuroactive molecules that directly or indirectly impact signalling in the brain. In this review, we will discuss how physical activity can be incorporated as a component of therapeutic strategies in oxidative stress-based neurological disorders along with the augmentation of probiotics intake.

The pH dependence of emulsifying properties for glutathione disulfide at oil-water interfaces

Although peptides were widely used in many fields, their interface behaviors as surfactants have not been explored. The results of the surface tension experiments by an automatic surface tension meter indicate that the stability and emulsifying ability of glutathione disulfide (GSSG) under alkaline conditions were stronger than those under acidic conditions. With encoding the different oxygen and nitrogen atoms in GSSG, as well as the different hydrogen atoms bonded with oxygen and nitrogen atoms. The pH Dependence of the number of hydrogen bonds, affected by the protonation and deprotonation of the functional groups in GSSG, is calculated by LAMMPS software. The results demonstrate that GSSG forms twice as many hydrogen bonds under alkaline conditions as under acidic conditions, resulting in a better surface-interface activity in alkaline conditions. The interface properties of the GSSG surfactant can be regulated by pH. Therefore, GSSG is a potential pH-responsive surfactant.

Metabolism Characteristics of Lactic Acid Bacteria and the Expanding Applications in Food Industry

Lactic acid bacteria are a kind of microorganisms that can ferment carbohydrates to produce lactic acid, and are currently widely used in the fermented food industry. In recent years, with the excellent role of lactic acid bacteria in the food industry and probiotic functions, their microbial metabolic characteristics have also attracted more attention. Lactic acid bacteria can decompose macromolecular substances in food, including degradation of indigestible polysaccharides and transformation of undesirable flavor substances. Meanwhile, they can also produce a variety of products including short-chain fatty acids, amines, bacteriocins, vitamins and exopolysaccharides during metabolism. Based on the above-mentioned metabolic characteristics, lactic acid bacteria have shown a variety of expanded applications in the food industry. On the one hand, they are used to improve the flavor of fermented foods, increase the nutrition of foods, reduce harmful substances, increase shelf life, and so on. On the other hand, they can be used as probiotics to promote health in the body. This article reviews and prospects the important metabolites in the expanded application of lactic acid bacteria from the perspective of bioengineering and biotechnology.

Peptide transporter-related protein 2 plays an important role in glutathione transport of Streptococcus thermophilus

Streptococcus thermophilus is widely used as a starter culture in the fermentation of yogurt. Glutathione (GSH; γ-glutamyl-cysteinyl-glycine), as a tripeptide, has an important physiological role for Strep. thermophilus. However, the scope of the GSH transport proteins is still unexplored in this species. In the present study, 5 peptide transporter-related proteins (Ptrp) of Strep. thermophilus strain ST-1 were selected and then inactivated by gene insertion, respectively. Through detection and comparison of intracellular GSH content of mutant strain and wild strain, we identified 2 proteins, named Ptrp-2 and Ptrp-4, that might be related to GSH transport. Reverse-transcriptase quantitative PCR was performed to verify the gene expressions of these 2 possible GSH transport-related proteins, and it was finally determined that Ptrp-2 plays an important role in GSH transport of Strep. thermophilus. Milk fermentation experiments were further conducted to test the effect of Ptrp-2 on the characteristics of yogurt. The results showed that the fermented milk hardly curds using the mutant strain, indicating that Ptrp-2 is important for Strep. thermophilus as a yogurt starter.

Pseudomonas aeruginosa Presents Multiple Vital Changes in Its Proteome in the Presence of 3-Hydroxyphenylacetic Acid, a Promising Antimicrobial Agent

Pseudomonas aeruginosa, a widely distributed opportunistic pathogen, is an important threat to human health for causing serious infections worldwide. Due to its antibiotic resistance and virulence factors, it is so difficult to combat this bacterium; thus, new antimicrobial agents are in search. 3-Hydroxyphenylacetic acid (3-HPAA), which is a phenolic acid mostly found in olive oil wastewater, can be a promising candidate with its dose-dependent antimicrobial properties. Elucidating the molecular mechanism of action is crucial for future examinations and the presentation of 3-HPAA as a new agent. In this study, the antimicrobial activity of 3-HPAA on P. aeruginosa and its action mechanism was investigated via shot-gun proteomics. The data, which are available via ProteomeXchange with identifier PXD016243, were examined by STRING analysis to determine the interaction networks of proteins. KEGG Pathway enrichment analysis via the DAVID bioinformatics tool was also performed to investigate the metabolic pathways that undetected and newly detected groups of the proteins. The results displayed remarkable changes after 3-HPAA exposure in the protein profile of P. aeruginosa related to DNA replication and repair, RNA modifications, ribosomes and proteins, cell envelope, oxidative stress, as well as nutrient availability. 3-HPAA showed its antimicrobial action on P. aeruginosa by affecting multiple bacterial processes; hence, it could be categorized as a multitarget antimicrobial agent.