Isolation and Identification of Limosilactobacillus reuteri PSC102 and Evaluation of Its Potential Probiotic, Antioxidant, and Antibacterial Properties

Modulating effects of heat-killed and live Limosilactobacillus reuteri PSC102 on the immune response and gut microbiota of cyclophosphamide-treated rats

In the present study, we investigated the potential immunomodulatory effects of heat-killed (hLR) and live Limosilactobacillus reuteri PSC102 (LR; formerly Lactobacillus reuteri PSC102) in RAW264.7 macrophage cells and Sprague-Dawley rats. RAW264.7 murine macrophage cells were stimulated with hLR and LR for 24 h. Cyclophosphamide (CTX)-induced immunosuppressed Sprague-Dawley rats were orally administered with three doses of hLR (L-Low, M-Medium, and H-High) and LR for 3 weeks. The phagocytic capacity, production of nitric oxide (NO), and expression of cytokines in RAW264.7 cells were measured, and the different parameters of immunity in rats were determined. hLR and LR treatments promoted phagocytic activity and induced the production of NO and the expression of iNOS, TNF-α, IL-1β, IL-6, and Cox-2 in macrophage cells. In the in vivo experiment, hLR and LR treatments significantly increased the immune organ indices, alleviated the spleen injury, and ameliorated the number of white blood cells, granulocytes, lymphocytes, and mid-range absolute counts in immunosuppressive rats. hLR and LR increased neutrophil migration and phagocytosis, splenocyte proliferation, and T lymphocyte subsets (CD4+, CD8+, CD45RA+, and CD28+). The levels of immune factors (IL-2, IL-4, IL-6, IL-10, IL-12A, TNF-α, and IFN-γ) in the hLR and LR groups were upregulated compared with those in the CTX-treatment group. hLR and LR treatments could also modulate the gut microbiota composition, thereby increasing the relative abundance of Bacteroidetes and Firmicutes but decreasing the level of Proteobacteria. hLR and LR protected against CTX-induced adverse reactions by modulating the immune response and gut microbiota composition. Therefore, they could be used as potential immunomodulatory agents.

The Whole-Genome Sequencing and Probiotic Profiling of Lactobacillus reuteri Strain TPC32 Isolated from Tibetan Pig

Gut microbiota are the microbial organisms that play a pivotal role in intestinal health and during disease conditions. Keeping in view the characteristic functions of gut microbiota, in this study, Lactobacillus reuteri TPC32 (L. reuteri TPC32) was isolated and identified, and its whole genome was analyzed by the Illumina MiSeq sequencing platform. The results revealed that L. reuteri TPC32 had high resistance against acid and bile salts with fine in vitro antibacterial ability. Accordingly, a genome sequence of L. reuteri TPC32 has a total length of 2,214,495 base pairs with a guanine-cytosine content of 38.81%. Based on metabolic annotation, out of 2,212 protein-encoding genes, 118 and 101 were annotated to carbohydrate metabolism and metabolism of cofactors and vitamins, respectively. Similarly, drug-resistance and virulence genes were annotated using the comprehensive antibiotic research database (CARD) and the virulence factor database (VFDB), in which vatE and tetW drug-resistance genes were annotated in L. reuteri TPC32, while virulence genes are not annotated. The early prevention of L. reuteri TPC32 reduced the Salmonella typhimurium (S. Typhimurium) infection in mice. The results show that L. reuteri TPC32 could improve the serum IgM, decrease the intestinal cytokine secretion to relieve intestinal cytokine storm, reinforce the intestinal biochemical barrier function by elevating the sIgA expression, and strengthen the intestinal physical barrier function. Simultaneously, based on the 16S rRNA analysis, the L. reuteri TPC32 results affect the recovery of intestinal microbiota from disease conditions and promote the multiplication of beneficial bacteria. These results provide new insights into the biological functions and therapeutic potential of L. reuteri TPC32 for treating intestinal inflammation.

Effect of folA gene in human breast milk-derived Limosilactobacillus reuteri on its folate biosynthesis

Introduction

Folate supplementation is crucial for the human body, and the chemically synthesized folic acid might have undesirable side effects. The use of molecular breeding methods to modify the genes related to the biosynthesis of folate by probiotics to increase folate production is currently a focus of research.

Methods

In this study, the folate-producing strain of Limosilactobacillus reuteri B1-28 was isolated from human breast milk, and the difference between B1-28 and folA gene deletion strain ΔFolA was investigated by phenotyping, in vitro probiotic evaluation, metabolism and transcriptome analysis.

Results

The results showed that the folate producted by the ΔFolA was 2-3 folds that of the B1-28. Scanning electron microscope showed that ΔFolA had rougher surface, and the acid-producing capacity (p = 0.0008) and adhesion properties (p = 0.0096) were significantly enhanced than B1-28. Transcriptomic analysis revealed that differentially expressed genes were mainly involved in three pathways, among which the biosynthesis of ribosome and aminoacyl-tRNA occurred in the key metabolic pathways. Metabolomics analysis showed that folA affected 5 metabolic pathways, involving 89 different metabolites.

Discussion

In conclusion, the editing of a key gene of folA in folate biosynthesis pathway provides a feasible pathway to improve folate biosynthesis in breast milk-derived probiotics.

Targeted Screening of Fiber Degrading Bacteria with Probiotic Function in Herbivore Feces

Cellulolytic bacteria with probiotic functions play a crucial role in promoting the intestinal health in herbivores. In this study, we aimed to correlate the 16S rRNA gene amplicon sequencing and fiber-degrading enzyme activity data from six different herbivore feces samples. By utilizing the separation and screening steps of probiotics, we targeted and screened high-efficiency fiber-degrading bacteria with probiotic functions. The animals included Maiwa Yak (MY), Holstein cow (CC), Tibetan sheep (TS), Southern Sichuan black goat (SG), Sichuan white rex rabbit (CR), and New Zealand white rabbit (ZR). The results showed that the enzymes associated with fiber degradation were higher in goat and sheep feces compared to cattle and rabbit's feces. Correlation analysis revealed that Bacillus and Fibrobacter were positively correlated with five types of fiber-degrading related enzymes. Notably, the relative abundance of Bacillus in the feces of Tibetan sheep was significantly higher than that of other five herbivores. A strain TS5 with good cellulose decomposition ability from the feces of Tibetan sheep by Congored staining, filter paper decomposition test, and enzyme activity determination was isolated. The strain was identified as Bacillus velezensis by biological characteristics, biochemical analysis, and 16S rRNA gene sequencing. To test the probiotic properties of Bacillus velezensis TS5, we evaluated its tolerance to acid and bile salt, production of digestive enzymes, antioxidants, antibacterial activity, and adhesion ability. The results showed that the strain had good tolerance to pH 2.0 and 0.3% bile salts, as well as good potential to produce cellulase, protease, amylase, and lipase. This strain also had good antioxidant capacity and the ability to antagonistic Staphylococcus aureus BJ216, Salmonella SC06, Enterotoxigenic Escherichia coli CVCC196, and Escherichia coli ATCC25922. More importantly, the strain had good self-aggregation and Caco-2 cell adhesion rate. In addition, we tested the safety of Bacillus velezensis TS5 by hemolysis test, antimicrobial susceptibility test, and acute toxicity test in mice. The results showed that the strain had no hemolytic phenotype, did not develop resistance to 19 commonly used antibiotics, had no cytotoxicity to Caco-2, and did not have acute toxic harm to mice. In summary, this study targeted isolated and screened a strain of Bacillus velezensis TS5 with high fiber-degrading ability and probiotic potency. This strain can be used as a potential probiotic for feeding microbial preparations for ruminants.

The Halotolerant Probiotic Bacterium Enterococcus lactis ASF-2 from Al-Asfar Lake, Saudi Arabia, Reduces Inflammation in Carrageenan-Induced Paw Edema

Inflammation-related diseases are major causes of mortality and disability worldwide. This study aimed to identify and investigate probiotic bacteria that could be present in Al-Asfar Lake in Al-Ahsa City, Saudi Arabia to prevent the inflammatory responses of carrageenan-induced paw edema. In total, seven active strains were isolated, and three isolates (ASF-1, ASF-2, and ASF-3) exhibited a positive Gram stain and viable growth at 20% NaCl salinity; they also lacked catalase and hemolytic activities and had high levels of cell surface hydrophobicity (CSH). They also demonstrated potent antibacterial activity against Salmonella typhi and Staphylococcus aureus. These results revealed that ASF-2 had probiotic qualities, and it was selected for further research. ASF-2 demonstrated significant anti-inflammatory effects in an experimental model of carrageenan-induced paw edema; the experimental model showed decreased levels of pro-inflammatory markers, such as interleukin 6 (IL-6), interleukin 17 (IL-17), and transforming growth factor-β (TGF-β), and an increased level of an anti-inflammatory marker (interferon gamma (IFN-γ)). Animals in the control group saw a 45% decrease in edema when compared to mice in the carrageenan group. When comparing tissue damage and infiltration in the ASF-2-treated and non-treated mice, the histological examination of the sub-planar tissues of the hind leg revealed that the inflamed tissues had healed. The 16S rRNA sequencing method was utilized to establish that ASF-2 is, in fact, Enterococcus lactis with a 99.2% sequence similarity. These findings shed further light on ASF-2's potential as a biocompatible anti-inflammatory medication.

Lactobacillus reuteri in digestive system diseases: focus on clinical trials and mechanisms

Objectives

Digestive system diseases have evolved into a growing global burden without sufficient therapeutic measures. Lactobacillus reuteri (L. reuteri) is considered as a new potential economical therapy for its probiotic effects in the gastrointestinal system. We have provided an overview of the researches supporting various L. reuteri strains' application in treating common digestive system diseases, including infantile colic, diarrhea, constipation, functional abdominal pain, Helicobacter pylori infection, inflammatory bowel disease, diverticulitis, colorectal cancer and liver diseases.

Methods

The summarized literature in this review was derived from databases including PubMed, Web of Science, and Google Scholar.

Results

The therapeutic effects of L. reuteri in digestive system diseases may depend on various direct and indirect mechanisms, including metabolite production as well as modulation of the intestinal microbiome, preservation of the gut barrier function, and regulation of the host immune system. These actions are largely strain-specific and depend on the activation or inhibition of various certain signal pathways. It is well evidenced that L. reuteri can be effective both as a prophylactic measure and as a preferred therapy for infantile colic, and it can also be recommended as an adjuvant strategy to diarrhea, constipation, Helicobacter pylori infection in therapeutic settings. While preclinical studies have shown the probiotic potential of L. reuteri in the management of functional abdominal pain, inflammatory bowel disease, diverticulitis, colorectal cancer and liver diseases, its application in these disease settings still needs further study.

Conclusion

This review focuses on the probiotic effects of L. reuteri on gut homeostasis via certain signaling pathways, and emphasizes the importance of these probiotics as a prospective treatment against several digestive system diseases.

Probiotics and Postbiotics as an Alternative to Antibiotics: An Emphasis on Pigs

Probiotics are being used as feed/food supplements as an alternative to antibiotics. It has been demonstrated that probiotics provide several health benefits, including preventing diarrhea, irritable bowel syndrome, and immunomodulation. Alongside probiotic bacteria-fermented foods, the different structural components, such as lipoteichoic acids, teichoic acids, peptidoglycans, and surface-layer proteins, offer several advantages. Probiotics can produce different antimicrobial components, enzymes, peptides, vitamins, and exopolysaccharides. Besides live probiotics, there has been growing interest in consuming inactivated probiotics in farm animals, including pigs. Several reports have shown that live and killed probiotics can boost immunity, modulate intestinal microbiota, improve feed efficiency and growth performance, and decrease the incidence of diarrhea, positioning them as an interesting strategy as a potential feed supplement for pigs. Therefore, effective selection and approach to the use of probiotics might provide essential features of using probiotics as an important functional feed for pigs. This review aimed to systematically investigate the potential effects of lactic acid bacteria in their live and inactivated forms on pigs.