Effect of bacteriocin-producing Pediococcus acidilactici strains on the immune system and intestinal flora of normal mice

Microbiome Taxonomic and Functional Differences in C3H/HeJ Mice Fed a Long-Term High-Fat Diet with Beef Protein ± Ammonium Hydroxide Supplementation

Studies have suggested that alkalinized foods may reduce the effects of the acidogenic Western diet in promoting obesity, metabolic syndrome, type 2 diabetes, cancer, and coronary heart disease. Indeed, a recent study in mice fed a high-fat diet containing dietary beef supplemented with ammonium hydroxide showed improvement in a suite of metabolic outcomes. However, the effects of dietary protein ammonium supplementation on the microbiome remain unknown. In this study, the effects of ammonium supplementation on beef protein towards microbiome taxa and function in a high-fat diet were analyzed. Fecal microbiomes were characterized using a shotgun metagenomic approach for 16-month-old male and female mice after long-term diet treatments. The results for ammoniated diets showed that several bacteria known to be associated with health benefits increased significantly, including Romboutsia, Oscillospiraceae, and Lactococcus cremoris. The beneficial mucin-degrader Akkermansia was especially abundant, with a high prevalence (~86%) in females. Concurrently, the phyla Actinomycetota (Actinobacteria) and Bacteroidota (Bacteroidetes) were significantly reduced. While sex was a confounding factor affecting microbiome responses to ammonium supplementation in dietary protein, it is worth noting that several putatively beneficial microbiome functions increased with ammonium supplementation, such as glycine betaine transport, xenobiotic detoxification, enhanced defense, and others. Conversely, many disease-associated microbiome functions reduced. Importantly, modifying protein pH alone via ammonium supplementation induced beneficial microbiota changes. Taken together, these results suggest that ammonium-supplemented proteins may mediate some negative microbiome-associated effects of high-fat/Western diets.

Gut Distribution, Impact Factor, and Action Mechanism of Bacteriocin-Producing Beneficial Microbes as Promising Antimicrobial Agents in Gastrointestinal Infection

Gastrointestinal (GI) infection by intestinal pathogens poses great threats to human health, and the therapeutic use of antibiotics has reached a bottleneck due to drug resistance. The developments of antimicrobial peptides produced by beneficial bacteria have drawn attention by virtue of effective, safe, and not prone to developing resistance. Though bacteriocin as antimicrobial agent in gut infection has been intensively investigated and reviewed, reviews on that of bacteriocin-producing beneficial microbes are very rare. It is important to explicitly state the prospect of bacteriocin-producing microbes in prevention of gastrointestinal infection towards their application in host. This review discusses the potential of gut as an appropriate resource for mining targeted bacteriocin-producing microbes. Then, host-related factors affecting the bacteriocin production and activity of bacteriocin-producing microbes in the gut are summarized. Accordingly, the multiple mechanisms (direct inhibition and indirect inhibition) behind the preventive effects of bacteriocin-producing microbes on gut infection are discussed. Finally, we propose several targeted strategies for the manipulation of bacteriocin-producing beneficial microbes to improve their performance in antimicrobial outcomes. We anticipate an upcoming emergence of developments and applications of bacteriocin-producing beneficial microbes as antimicrobial agent in gut infection induced by pathogenic bacteria.

Protective Effects of Bacteriocin-Producing Lactiplantibacillus plantarum on Intestinal Barrier of Mice

Bacteriocins are crucial metabolites of probiotics that display beneficial functions. The intestinal barrier is an important target on which probiotics exert their intestinal health activity. However, the impacts of bacteriocin-producing probiotics on the intestinal barrier are unclear. In this study, the effects of bacteriocin-producing Lactiplantibacillus plantarum Q7 and L. plantarum F3-2 on the intestinal barrier of mice were explored. It was shown that L. plantarum Q7 promoted the expression of mucin MUC2 to enhance the protection provided by the intestinal mucus layer. L. plantarum Q7 up-regulated the gene expression of intestinal tight junction proteins ZO-1 and JAM-1 significantly, and L. plantarum F3-2 up-regulated ZO-1 and Claudin-1 markedly, which exhibited tight junction intestinal barrier function. The two strains promoted the release of IgA and IgG at varying degrees. The antimicrobial peptide gene RegIIIγ was up-regulated markedly, and the gene expression of inflammatory cytokines appeared to exhibit an upward trend with L. plantarum Q7 treatment, so as to enhance intestinal immune regulation function. Furthermore, L. plantarum Q7 and L. plantarum F3-2 increased the abundance of the beneficial bacteria Muribaculaceae, inhibited the growth of the harmful bacteria Parabacteroides, and facilitated the synthesis of total short-chain fatty acids (SCFAs), which seemed to favor the prevention of metabolic diseases. Our results suggested that L. plantarum Q7 and L. plantarum F3-2 showed strain specificity in their protective effects on the intestinal chemical, physical, immunological and biological barriers of mice, which provided theoretical support for the selective utilization of bacteriocin-producing strains to regulate host health.

Bacteriocin-Producing Lactiplantibacillus plantarum YRL45 Enhances Intestinal Immunity and Regulates Gut Microbiota in Mice

Bacteriocins production is one of important beneficial characteristics of probiotics, which has antibacterial property against intestinal pathogens and is helpful for regulating intestinal flora. To investigate the impact of bacteriocin-producing probiotics on gut microecology, bacteriocin-producing Lactiplantibacillus plantarum YRL45 was orally administered to mice. The results revealed that it promoted the release of cytokines and improved the phagocytic activity of peritoneal macrophages to activate the immune regulation system. L. plantarum YRL45 was conducive to maintaining the morphology of colon tissue without inflammation and increasing the ratio of villus height to crypt depth in the ileum. The gene expression levels of Muc2, ZO-1 and JAM-1 were significantly up-regulated in the ileum and colon, and the gene expression of Cramp presented an upward trend with L. plantarum YRL45 intervention. Moreover, L. plantarum YRL45 remarkably enhanced the levels of immunoglobulins sIgA, IgA and IgG in the intestine of mice. The 16S rRNA gene analysis suggested that L. plantarum YRL45 administration up-regulated the relative abundance of the beneficial bacteria Muribaculaceae and Akkermansia, down-regulated the abundance of the pathogenic bacteria Lachnoclostridium, and promoted the production of acetic acid, propionic acid and total short-chain fatty acids (SCFAs) in mice feces. Our findings indicated that L. plantarum YRL45 had the potential to be developed as a novel probiotic to regulate the intestinal barrier by altering gut microbiota to enhance intestinal immunity and ameliorate intestinal flora balance.

Biofilm-based delivery approaches and specific enrichment strategies of probiotics in the human gut

The use of probiotics has been one of the effective strategies to restructure perturbed human gut microbiota following a disease or metabolic disorder. One of the biggest challenges associated with the use of probiotic-based gut modulation strategies is to keep the probiotic cells viable and stable during the gastrointestinal transit. Biofilm-based probiotics delivery approaches have emerged as fascinating modes of probiotic delivery in which probiotics show significantly greater tolerance and biotherapeutic potential, and interestingly probiotic biofilms can be developed on food-grade surfaces too, which is ideal for the growth and proliferation of bacterial cells for incorporation into food matrices. In addition, biofilms can be further encapsulated with food-grade materials or with bacterial self-produced biofilms. This review presents a newly emerging and unprecedently discussed techniques for the safe delivery of probiotics based on biofilms and further discusses newly emerging prebiotic materials which target specific gut microbiota groups for growth and proliferation.

Bacteriocins as Potential Therapeutic Approaches in the Treatment of Various Cancers: A Review of In Vitro Studies

Simple Summary

Current cancer treatment strategies such as surgery, chemotherapy, and radiotherapy, have significant drawbacks. There is a need for a breakthrough approach to cancer treatment. Bacteriocin, an antimicrobial peptide, has shown several anticancer properties in vitro. Therefore, this article reviews the effect of bacteriocin on cancer cells and how bacteriocins affect cancer cells in vitro. This article aims to promote additional bacteriocin research, particularly in vivo studies, to fully understand the potential of bacteriocin as a cancer treatment agent.

Abstract

Cancer is regarded as one of the most common and leading causes of death. Despite the availability of conventional treatments against cancer cells, current treatments are not the optimal treatment for cancer as they possess the possibility of causing various unwanted side effects to the body. As a result, this prompts a search for an alternative treatment without exhibiting any additional side effects. One of the promising novel therapeutic candidates against cancer is an antimicrobial peptide produced by bacteria called bacteriocin. It is a non-toxic peptide that is reported to exhibit potency against cancer cell lines. Experimental studies have outlined the therapeutic potential of bacteriocin against various cancer cell lines. In this review article, the paper focuses on the various bacteriocins and their cytotoxic effects, mode of action and efficacies as therapeutic agents against various cancer cell lines.

Recombinant Lactococcus lactis Expressing Grass Carp Reovirus VP6 Induces Mucosal Immunity Against Grass Carp Reovirus Infection

Grass carp haemorrhagic disease caused by grass carp reovirus II is a serious disease of the aquaculture industry and vaccination is the only effective method of GCRV protection. In this study, Lactococcus lactis was used as oral vaccine delivery to express the GCRV II VP6 protein. We evaluated the protective efficacy of the live vaccine strain to induce mucosal immune protection. After oral administration, the recombinant strains remained in the hindgut for antigen presentation and increased the survival rate 46.7% and the relative percent survival 42.9%, respectively versus control vaccination. Though L. lactis alone can induce the inflammatory response by stimulating the mucosal immune system, the recombinant L. lactis expressing VP6 greatly enhanced nonspecific immune responses via expression of immune related genes of the fish. Furthermore, both systemic and mucosal immunity was elicited following oral immunization with the recombinant strain and this strain also elicited an inflammatory response and cellular immunity to enhance the protective effect. L. lactis can therefore be utilized as a mucosal immune vector to trigger high levels of immune protection in fish at both the systemic and mucosal levels. L. lactis is a promising candidate for oral vaccine delivery.

Screening and Probiotic Potential Evaluation of Bacteriocin-Producing Lactiplantibacillus plantarum In Vitro

Probiotics are gaining attention due to their functions of regulating the intestinal barrier and promoting human health. The production of bacteriocins is one of the important factors for probiotics to exert beneficial properties. This study aimed to screen bacteriocin-producing Lactiplantibacillus plantarum and evaluate the probiotic potential in vitro. It was found that L. plantarum Q7, L. plantarum F3-2 and L. plantarum YRL45 could produce bacteriocins and inhibit common intestinal pathogens. These three strains had probiotic potential with tolerance to the gastrointestinal environmental and colonization in the gut, and exhibited various degrees of anti-inflammatory activity and tight junction function in the intestinal barrier. Particularly, L. plantarum YRL45 could significantly (p < 0.05) reduce the increase in nitric oxide (NO), prostaglandin E2 (PGE2), necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) induced by lipopolysaccharide (LPS), thereby easing inflammatory response. L. plantarum F3-2 could remarkably (p < 0.05) up-regulate the expression levels of ZO-1, Occludin and Claudin-1 in intestinal epithelial injured cells, which was conducive to protecting the intestinal barrier. These findings provided fundamental information about the probiotic properties of bacteriocin-producing L. plantarum, which suggested that L. plantarum Q7, L. plantarum F3-2 and L. plantarum YRL45 had the potential to be used as novel probiotic strains.