Probiotic Bacillus subtilis LF11 Protects Intestinal Epithelium Against Salmonella Infection

Evaluating the Safety of Bacillus cereus GW-01 Obtained from Sheep Rumen Chyme

Bacillus cereus is responsible for 1.4-12% food poisoning outbreaks worldwide. The safety concerns associated with the applications of B. cereus in health and medicine have been controversial due to its dual role as a pathogen for foodborne diseases and a probiotic in humans and animals. In this study, the pathogenicity of B. cereus GW-01 was assessed by comparative genomic, and transcriptome analysis. Phylogenetic analysis based on a single-copy gene showed clustering of the strain GW-01, and 54 B. cereus strains from the NCBI were classified into six major groups (I-VI), which were then associated with the source region and sequence types (STs). Transcriptome results indicated that the expression of most genes related with toxins secretion in GW-01 was downregulated compared to that in the lag phase. Overall, these findings suggest that GW-01 is not directly associated with pathogenic Bacillus cereus and highlight an insightful strategy for assessing the safety of novel B. cereus strains.

Deciphering Microbiome, Transcriptome, and Metabolic Interactions in the Presence of Probiotic Lactobacillus acidophilus against Salmonella Typhimurium in a Murine Model

Salmonella enterica serovar Typhimurium (S. Typhimurium), a foodborne pathogen that poses significant public health risks to humans and animals, presents a formidable challenge due to its antibiotic resistance. This study explores the potential of Lactobacillus acidophilus (L. acidophilus 1.3251) probiotics as an alternative strategy to combat antibiotic resistance associated with S. Typhimurium infection. In this investigation, twenty-four BALB/c mice were assigned to four groups: a non-infected, non-treated group (CNG); an infected, non-treated group (CPG); a group fed with L. acidophilus but not infected (LAG); and a group fed with L. acidophilus and challenged with Salmonella (LAST). The results revealed a reduction in Salmonella levels in the feces of mice, along with restored weight and improved overall health in the LAST compared to the CPG. The feeding of L. acidophilus was found to downregulate pro-inflammatory cytokine mRNA induced by Salmonella while upregulating anti-inflammatory cytokines. Additionally, it influenced the expression of mRNA transcript, encoding tight junction protein, oxidative stress-induced enzymes, and apoptosis-related mRNA expression. Furthermore, the LEfSe analysis demonstrated a significant shift in the abundance of critical commensal genera in the LAST, essential for maintaining gut homeostasis, metabolic reactions, anti-inflammatory responses, and butyrate production. Transcriptomic analysis revealed 2173 upregulated and 506 downregulated differentially expressed genes (DEGs) in the LAST vs. the CPG. Functional analysis of these DEGs highlighted their involvement in immunity, metabolism, and cellular development. Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analysis indicated their role in tumor necrosis factor (TNF), mitogen-activated protein kinase (MAPK), chemokine, Forkhead box O (FOXO), and transforming growth factor (TGF-β) signaling pathway. Moreover, the fecal metabolomic analysis identified 929 differential metabolites, with enrichment observed in valine, leucine, isoleucine, taurine, glycine, and other metabolites. These findings suggest that supplementation with L. acidophilus promotes the growth of beneficial commensal genera while mitigating Salmonella-induced intestinal disruption by modulating immunity, gut homeostasis, gut barrier integrity, and metabolism.

Anticancer activities of natural antimicrobial peptides from animals

Cancer is the most common cause of human death worldwide, posing a serious threat to human health and having a negative impact on the economy. In the past few decades, significant progress has been made in anticancer therapies, but traditional anticancer therapies, including radiation therapy, surgery, chemotherapy, molecular targeted therapy, immunotherapy and antibody-drug conjugates (ADCs), have serious side effects, low specificity, and the emergence of drug resistance. Therefore, there is an urgent need to develop new treatment methods to improve efficacy and reduce side effects. Antimicrobial peptides (AMPs) exist in the innate immune system of various organisms. As the most promising alternatives to traditional drugs for treating cancers, some AMPs also have been proven to possess anticancer activities, which are defined as anticancer peptides (ACPs). These peptides have the advantages of being able to specifically target cancer cells and have less toxicity to normal tissues. More and more studies have found that marine and terrestrial animals contain a large amount of ACPs. In this article, we introduced the animal derived AMPs with anti-cancer activity, and summarized the types of tumor cells inhibited by ACPs, the mechanisms by which they exert anti-tumor effects and clinical applications of ACPs.

Determining the In Vivo Efficacy of Plant-Based and Probiotic-Based Antibiotic Alternatives against Mixed Infection with Salmonella enterica and Escherichia coli in Domestic Chickens

Restrictions on the use of antimicrobial compounds have led to a surge of interest in alternative solutions, such as natural, plant-based compounds. In our study, we investigated the efficacy of three feed supplements containing different additives, namely, probiotics (Lactobacillus spp., "Test substance A"), turmeric (Curcuma longa L., "Test substance B"), and fenugreek (Trigonella foenum graecum, "Test substance C"). In the experiment, we tested 180 birds of the Bábolna Tetra-SL laying hybrid breed that were infected with Salmonella enteritidis strains. The birds were randomly divided into six groups: three groups treated with the different additives, a negative control group, a positive control group, and an antibiotic-treated group using enrofloxacin. We examined the maturation and the time course of shedding of Salmonella; at the end of rearing, pathological and histopathological examinations were performed. When Salmonella was isolated from the cloacal swab samples, the enrofloxacin-treated group had a high number of animals shedding Salmonella by day 9, which was like the group treated with test material C. The greatest reduction in Salmonella shedding was observed in the groups treated with test materials A and B. In terms of pathological parameters, villus length and crypt depth were significantly better in the group treated with test material C compared to the positive and negative controls, and when comparing the body weight of the tested animals, the group treated with test material B had a significantly larger absorption surface area compared to the positive control group. Overall, the supplement with test material C proved to be the most effective. In the future, it is worthwhile to investigate the combination of the tested active substances for their possible synergistic effects and to perform a dose-response study to select the optimal dosage.

The gut microbiome tango in the progression of chronic kidney disease and potential therapeutic strategies

Chronic kidney disease (CKD) affects more than 10% population worldwide and becomes a huge burden to the world. Recent studies have revealed multifold interactions between CKD and gut microbiome and their pathophysiological implications. The gut microbiome disturbed by CKD results in the imbalanced composition and quantity of gut microbiota and subsequent changes in its metabolites and functions. Studies have shown that both the dysbiotic gut microbiota and its metabolites have negative impacts on the immune system and aggravate diseases in different ways. Herein, we give an overview of the currently known mechanisms of CKD progression and the alterations of the immune system. Particularly, we summarize the effects of uremic toxins on the immune system and review the roles of gut microbiota in promoting the development of different kidney diseases. Finally, we discuss the current sequencing technologies and novel therapies targeting the gut microbiome.

Protective Effects of Bacillus subtilis HH2 against Oral Enterotoxigenic Escherichia coli in Beagles

This study evaluated the protective effect of Bacillus subtilis HH2 on beagles orally challenged with enterotoxigenic Escherichia coli (ETEC). We assessed the physiological parameters and the severity of diarrhea, as well as the changes in three serum immunoglobulins (IgG, IgA, and IgM), plasma diamine oxidase (DAO), D-lactate (D-LA), and the fecal microbiome. Feeding B. subtilis HH2 significantly reduced the severity of diarrhea after the ETEC challenge (p < 0.05) and increased serum levels of IgG, IgA, and IgM (p < 0.01). B. subtilis HH2 administration also reduced serum levels of DAO at 48 h after the ETEC challenge (p < 0.05), but no significant changes were observed in D-LA (p > 0.05). Oral ETEC challenge significantly reduced the richness and diversity of gut microbiota in beagles not pre-fed with B. subtilis HH2 (p < 0.05), while B. subtilis HH2 feeding and oral ETEC challenge significantly altered the gut microbiota structure of beagles (p < 0.01). Moreover, 14 days of B. subtilis HH2 feeding reduced the relative abundance of Deinococcus-Thermus in feces. This study reveals that B. subtilis HH2 alleviates diarrhea caused by ETEC, enhances non-specific immunity, reduces ETEC-induced damage to the intestinal mucosa, and regulates gut microbiota composition.

Bacterial Spore-Based Delivery System: 20 Years of a Versatile Approach for Innovative Vaccines

Mucosal vaccines offer several advantages over injectable conventional vaccines, such as the induction of adaptive immunity, with secretory IgA production at the entry site of most pathogens, and needle-less vaccinations. Despite their potential, only a few mucosal vaccines are currently used. Developing new effective mucosal vaccines strongly relies on identifying innovative antigens, efficient adjuvants, and delivery systems. Several approaches based on phages, bacteria, or nanoparticles have been proposed to deliver antigens to mucosal surfaces. Bacterial spores have also been considered antigen vehicles, and various antigens have been successfully exposed on their surface. Due to their peculiar structure, spores conjugate the advantages of live microorganisms with synthetic nanoparticles. When mucosally administered, spores expressing antigens have been shown to induce antigen-specific, protective immune responses. This review accounts for recent progress in the formulation of spore-based mucosal vaccines, describing a spore's structure, specifically the spore surface, and the diverse approaches developed to improve its efficiency as a vehicle for heterologous antigen presentation.

Lysinibacillus capsici 38,328 isolated from agricultural soils as a promising probiotic candidate for intestinal health

There is an increasing interest in the use of spore-forming Bacillus spp. as probiotic ingredients on the market. However, probiotics Bacillus species are insufficient, and more safe Bacillus species were required. In the study, traditional fermented foods and soil samples were collected from more than ten provinces in China, and 506 Bacillus were selected from 109 samples. Using the optimized procedure, we screened nine strains, which successfully passed the acid, alkali, bile salt, and trypsin resistance test. Drug sensitivity test results showed that three Bacillus out of the nine isolates exhibited antibiotic sensitivity to more than 29 antibiotics. The three strains sensitive to antibiotics were identified by 16S ribosomal RNA, recA, and gyrB gene analysis, two isolates (38,327 and 38,328) belong to the species Lysinibacillus capsici and one isolate (37,326) belong to Bacillus halotolerans. Moreover, the three strains were confirmed safe through animal experiments. Finally, L. capsici 38,327 and 38,328 showed protections in the Salmonella typhimurium infection mouse model, which slowed down weight loss, reduced bacterial load, and improved antioxidant capacity. Altogether, our data demonstrated that selected L. capsici strains can be used as novel probiotics for intestinal health.

Nutrient Availability and Biofilm Polysaccharide Shape the Bacillaene-Dependent Antagonism of Bacillus subtilis against Salmonella Typhimurium

Salmonella enterica is one of the most common foodborne pathogens and, due to the spread of antibiotic resistance, new antimicrobial strategies are urgently needed to control it. In this study, we explored the probiotic potential of Bacillus subtilis PS-216 and elucidated the mechanisms that underlie the interactions between this soil isolate and the model pathogenic strain S. Typhimurium SL1344. The results reveal that B. subtilis PS-216 inhibits the growth and biofilm formation of S. Typhimurium through the production of the pks cluster-dependent polyketide bacillaene. The presence of S. Typhimurium enhanced the activity of the PpksC promoter that controls bacillaene production, suggesting that B. subtilis senses and responds to Salmonella. The level of Salmonella inhibition, overall PpksC activity, and PpksC induction by Salmonella were all higher in nutrient-rich conditions than in nutrient-depleted conditions. Although eliminating the extracellular polysaccharide production of B. subtilis via deletion of the epsA-O operon had no significant effect on inhibitory activity against Salmonella in nutrient-rich conditions, this deletion mutant showed an enhanced antagonism against Salmonella in nutrient-depleted conditions, revealing an intricate relationship between exopolysaccharide production, nutrient availability, and bacillaene synthesis. Overall, this work provides evidence on the regulatory role of nutrient availability, sensing of the competitor, and EpsA-O polysaccharide in the social outcome of bacillaene-dependent competition between B. subtilis and S. Typhimurium. IMPORTANCE Probiotic bacteria represent an alternative for controlling foodborne disease caused by Salmonella enterica, which constitutes a serious concern during food production due to its antibiotic resistance and resilience to environmental stress. Bacillus subtilis is gaining popularity as a probiotic, but its behavior in biofilms with pathogens such as Salmonella remains to be elucidated. Here, we show that the antagonism of B. subtilis is mediated by the polyketide bacillaene and that the production of bacillaene is a highly dynamic trait which depends on environmental factors such as nutrient availability and the presence of competitors. Moreover, the production of extracellular polysaccharides by B. subtilis further alters the influence of these factors. Hence, this work highlights the inhibitory effect of B. subtilis, which is condition-dependent, and the importance of evaluating probiotic strains under conditions relevant to the intended use.