Screening, Safety Evaluation, and Mechanism of Two Lactobacillus fermentum Strains in Reducing the Translocation of Staphylococcus aureus in the Caco-2 Monolayer Model

Limosilactobacillus fermentum NCU003089 and Lactiplantibacillus plantarum NCU001261, two probiotics with inhibition of Escherichia coli and Cronobacter sakazakii translocation in vitro

The subject of this study was to screen lactic acid bacteria (LAB) with pathogen translocation inhibition and investigate the potential inhibition mechanism of it. Pathogens colonized in the intestine could cross the intestinal barrier to access blood circulation, causing severe complications. This study aimed to screen LAB with favorable inhibitory effects on the translocation of enterinvasive Escherichia coli CMCC44305 (E. coli) and Cronobacter sakazakii CMCC45401 (C. sakazakii), which were two common intestinal opportunistic pathogens. After an elaborate screening procedure including adhesion, antibacterial, and translocation assay, Limosilactobacillus fermentum NCU003089 (L. fermentum NCU3089) and Lactiplantibacillus plantarum NCU0011261 (L. plantarum NCU1261) were found to inhibit 58.38% and 66.85% of pathogen translocation, respectively. Subsequently, LAB pre-treatment suppressed the decline in TEER of Caco-2 monolayers caused by pathogens. Meanwhile, L. fermentum NCU3089 significantly inhibited claudin-1, ZO-1, and JAM-1 degradation caused by E. coli, and L. plantarum NCU1261 markedly reduced claudin-1 degradation caused by C. sakazakii. Also, the two LAB strains significantly decreased TNF-α level. In addition, L. fermentum NCU3089 but not L. plantarum NCU1261 tolerated well in the gastrointestinal fluids, and they were both sensitive or intermediate to nine common clinical antibiotics without hemolytic activity. In short, the two LAB strains could inhibit pathogen translocation by competing for adhesion sites, secreting antibacterial substances, reducing inflammatory cytokines levels, and maintaining intestinal barrier integrity. This study provided a feasible solution to prevent pathogen infection and translocation, and the two LAB strains were safe and had potential in food and pharmaceutical applications.

Limosilactobacillus fermentum from buffalo milk is suitable for potential biotechnological process development and inhibits Helicobacter pylori in a gastric epithelial cell model

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L.fermentum from buffalo milk grows efficiently without animal-derived medium components.

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Highest viable biomass titers can be reached after only 8h improving productivity.

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L. fermentum is suitable for large scale production: complete biotech approach.

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L. fermentum demonstrates 60% cell survival after spray drying.

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L. fermentum from buffalo milk displaces H. pylori in a gastric epithelial cell model.

Probiotics are living microorganisms that give beneficial health effects while consumed, and each strain possesses diverse and unique properties and also different technological characteristics that affect its ability to be produced at large scale. Limosilactobacillus fermentum is a widely studied member of probiotics, however, few data are available on the development of fermentation and downstream processes for the production of viable biomasses for potential industrial applications.

In the present study a novel L. fermentum strain was isolated from buffalo milk and used as test example for biotechnological process development. The strain was able to produce up to 10⁹ CFU/mL on a (glucose based) semi-defined medium deprived of animal-derived raw materials up to the pilot scale (150 L), demonstrating improved results compared to commonly used, although industrially not suitable, media rich of casein and beef extract. The study of strain behavior in batch experiments indicated that the highest concentration of viable cells was reached after only 8 h of growth, greatly shortening the process. Moreover, initial concentrations of glucose in the medium above 30 g/L, if not supported by higher nitrogen concentrations, reduced the yield of biomass and increased production of heterolactic fermentation by-products. Biomass concentration via microfiltration on hollow fibers, and subsequent spray-drying allowed to recover about 5.7 × 10¹⁰CFU/g_powder of viable cells, indicating strain resistance to harsh processing conditions.

Overall, these data demonstrate the possibility to obtain and maintain adequate levels of viable L. fermentum cells by using a simple approach that is potentially suitable for industrial development. Moreover, since often exopolysaccharides produced by lactobacilli contribute to the strain's functionality, a partial characterization of the EPS produced by the newly identified L. fermentum strain was carried out.

Finally, the effect of L. fermentum versus H. pylori in a gastric epithelial cell model was evaluated demonstrating its ability to stimulate the response of the immune system and displace the infective agent.

Lacticaseibacillus rhamnosus FM9 and Limosilactobacillus fermentum Y57 Are as Effective as Statins at Improving Blood Lipid Profile in High Cholesterol, High-Fat Diet Model in Male Wistar Rats

Elevated serum cholesterol is a major risk factor for coronary heart diseases. Some Lactobacillus strains with cholesterol-lowering potential have been isolated from artisanal food products. The purpose of this study was to isolate probiotic Lactobacillus strains from traditional yoghurt (dahi) and yogurt milk (lassi) and investigate the impact of these strains on the blood lipid profile and anti-obesity effect in a high cholesterol high fat diet model in Wistar rats. Eight candidate probiotic strains were chosen based on in vitro probiotic features and cholesterol reduction ability. By 16S rDNA sequencing, these strains were identified as Limosilactibacillus fermentum FM6, L. fermentum FM16, L. fermentum FM12, Lacticaseibacillus rhamnosus FM9, L. fermentum Y55, L. fermentum Y57, L. rhamnosus Y59, and L. fermentum Y63. The safety of these strains was investigated by feeding 2 × 10⁸ CFU/mL in saline water for 28 days in a Wistar rat model. No bacterial translocation or any other adverse effects were observed in animals after administration of strains in water, which indicates the safety of strains. The cholesterol-lowering profile of these probiotics was evaluated in male Wistar rats using a high-fat, high-cholesterol diet (HFCD) model. For 30 days, animals were fed probiotic strains in water with 2 × 10⁸ CFU/mL/rat/day, in addition to a high fat, high cholesterol diet. The cholesterol-lowering effects of various probiotic strains were compared to those of statin. All strains showed improvement in total cholesterol, LDL, HDL, triglycerides, and weight gain. Serum cholesterol levels were reduced by 9% and 8% for L. rhamnosus FM9 and L. fermentum Y57, respectively, compared to 5% for the statin-treated group. HDL levels significantly improved by 46 and 44% for L. rhamnosus FM9 and L. fermentum Y57, respectively, compared to 46% for the statin-treated group. Compared to the statin-treated group, FM9 and Y57 significantly reduced LDL levels by almost twofold. These findings show that these strains can improve blood lipid profiles as effectively as statins in male Wistar rats. Furthermore, probiotic-fed groups helped weight control in animals on HFCD, indicating the possible anti-obesity potential of these strains. These strains can be used to develop food products and supplements to treat ischemic heart diseases and weight management. Clinical trials, however, are required to validate these findings.

Therapeutic and Improving Function of Lactobacilli in the Prevention and Treatment of Cardiovascular-Related Diseases: A Novel Perspective From Gut Microbiota

The occurrence and development of cardiovascular-related diseases are associated with structural and functional changes in gut microbiota (GM). The accumulation of beneficial gut commensals contributes to the improvement of cardiovascular-related diseases. The cardiovascular-related diseases that can be relieved by Lactobacillus supplementation, including hypercholesterolemia, atherosclerosis, myocardial infarction, heart failure, type 2 diabetes mellitus, and obesity, have expanded. As probiotics, lactobacilli occupy a substantial part of the GM and play important functional roles through various GM-derived metabolites. Lactobacilli ultimately have a beneficial impact on lipid metabolism, inflammatory factors, and oxidative stress to relieve the symptoms of cardiovascular-related diseases. However, the axis and cellular process of gut commensal Lactobacillus in improving cardiovascular-related diseases have not been fully elucidated. Additionally, Lactobacillus strains produce diverse antimicrobial peptides, which help maintain intestinal homeostasis and ameliorate cardiovascular-related diseases. These strains are a field that needs to be further investigated immediately. Thus, this review demonstrated the mechanisms and summarized the evidence of the benefit of Lactobacillus strain supplementation from animal studies and human clinical trials. We also highlighted a broad range of lactobacilli candidates with therapeutic capability by mining their metabolites. Our study provides instruction in the development of lactobacilli as a functional food to improve cardiovascular-related diseases.