In vitro inhibition of Clostridium difficile and Clostridium perfringens by commercial probiotic strains

Lactiplantibacillus plantarum GMNL-661 Ameliorates Clostridioides difficile Infection and Reconfigures Intestinal Microbiota in a Murine Model

Clostridioides difficile infection (CDI) is a significant global health threat, often resulting from antibiotic-induced disruption of the gut microbiota, which leads to severe gastrointestinal issues. Current treatments, such as vancomycin, are effective but can cause subsequent relapses, further microbiota disruption, and high treatment costs. Probiotics offer a promising microbiota-based therapeutic strategy. Following an in vitro screening for novel lactic acid bacterial (LAB) strains with strong anti-C. difficile ability and good tolerance to digestive challenges, Lactiplantibacillus plantarum GMNL-661 emerged as a potential solution to combat CDI. In a CDI mice model, the appropriate dose of GMNL-661 effectively alleviated CDI, which caused weight loss, gut inflammation, and mucin depletion. GMNL-661 alleviated CDI symptoms through increased gut barrier genes and downregulated IL-1 and IL-18. 16s rDNA analysis of mice stool from CDI and CDI supplemented with GMNL-661 showed distinct microbiota ecology. GMNL-661 dramatically affected the microbiome of CDI, increasing Lactobacillus spp. and Clostridium cluster XVIII while reducing Clostridium and Enterococcus species. Genome analysis of GMNL-661 revealed minimal safety concerns in antibiotic resistance and virulence genes, confirming that it is suitable for inclusion in the food chain. Antimicrobial peptide (AMP) prediction on GMNL-661 and 299v genome suggested a strong potential candidate for anti-CD antimicrobial peptides. These findings highlighted L. plantarum GMNL-661 as an effective and highly safe therapeutic agent against CDI in clinical.

In Vitro Investigation of the Effects of Bacillus subtilis-810B and Bacillus licheniformis-809A on the Rumen Fermentation and Microbiota

Direct-fed microbials (DFMs) have shown the potential to improve livestock performance and overall health. Extensive research has been conducted to identify new DFMs and understand their mechanisms of action in the gut. Bacillus species are multifunctional spore-forming bacteria that exhibit resilience to harsh conditions, making them ideal candidates for applications in the feed industry and livestock production. This study investigates the mode of action of B. licheniformis and B. subtilis in the rumen using diverse in vitro techniques. Our results revealed that both strains germinated and grew in sterile rumen and intestinal contents from dairy cows and bulls. Gas composition analysis of in vitro cultures in a medium containing 40% rumen fluid demonstrated that germination of B. licheniformis and B. subtilis strains reduced oxygen levels, promoting an anaerobic environment favorable to rumen microbes. Enzymatic activity assays showed that B. licheniformis released sugars from complex substrates and purified polysaccharides in filtered rumen content. Additionally, the combination of B. licheniformis and B. subtilis survived and grew in the presence of a commercial monensin dose in rumen fluid media. The effects of B. licheniformis and B. subtilis on rumen fermentation activity and microbiota were studied using an in vitro batch fermentation assay. In fermenters that received a combination of B. licheniformis and B. subtilis, less CO2 was produced while dry matter degradation and CH4 production was comparable to the control condition, indicating better efficiency of dry matter utilization by the microbiota. The investigation of microbiota composition between supplemented and control fermenters showed no significant effect on alpha and beta diversity. However, the differential analysis highlighted changes in several taxa between the two conditions. Altogether, our data suggests that the administration of these strains of Bacillus could have a beneficial impact on rumen function, and consequently, on health and performance of ruminants.

Effects of Kimchi-Derived Lactic Acid Bacteria on Reducing Biological Hazards in Kimchi

This study was performed to investigate the use of plant-based lactic acid bacteria (LAB) to reduce microbiological hazards in kimchi. Cell-free supernatants (CFS) from four LAB strains isolated from kimchi were tested for antimicrobial activity against five foodborne pathogens and two soft-rot pathogens. Each CFS showed antimicrobial activity against both foodborne and soft-rot pathogens. Washing salted kimchi cabbages inoculated with B. cereus with 5% CFS inhibited B. cereus to a greater extent than NaClO. The CFS from WiKim 83 and WiKim 87 exhibits inhibition rates of 25.09% and 24.21%, respectively, compared to the 19.19% rate of NaClO. Additionally, the CFS from WiKim 116 and WiKim 117 showed inhibition rates of 18.74% and 20.03%, respectively. Direct treatment of kimchi cabbage with soft-rot pathogens and CFS for five days inhibited the pathogens with similar efficacy to that of NaClO. To elucidate the antimicrobial activity mechanisms, pH neutralization, heat treatment, and organic acid analyses were performed. pH neutralization reduced the antimicrobial activity, whereas heat treatment did not, indicating that lactic, acetic, citric, and phenyllactic acids contribute to the thermal stability and antimicrobial properties of CFS. This study suggests that the four kimchi-derived LAB, which maintain a low pH through organic acid production, could be viable food preservatives capable of reducing biological hazards in kimchi.

Lactococcus lactis MA5 is a potential autochthonous probiotic for nutrient digestibility enhancement and bacterial pathogen inhibition in hybrid catfish (Ictalurus punctatus × I. furcatus)

With the emergence of diseases, the U.S. catfish industry is under challenge. Current trends prefer autochthonous bacteria as potential probiotic candidates owing to their adaptability and capacity to effectively colonize the host's intestine, which can enhance production performance and bolster disease resistance. The objective of this study was to isolate an autochthonous bacterium as probiotic for hybrid catfish. Initially, an analysis of the intestinal microbiota of hybrid catfish reared in earthen ponds was conducted for subsequent probiotic development. Twenty lactic acid bacteria were isolated from the digesta of overperforming catfish, and most of the candidates demonstrated probiotic traits, including proteolytic and lipolytic abilities; antagonistic inhibition of catfish enteric bacterial pathogens, negative haemolytic activity and antibiotic susceptibility. Subsequent to this screening process, an isolate of Lactococcus lactis (MA5) was deemed the most promising probiotic candidate. In silico analyses were conducted, and several potential probiotic functions were predicted, including essential amino acids and vitamin synthesis. Moreover, genes for three bacteriocins, lactococcin A, enterolysin A and sactipeptide BmbF, were identified. Lastly, various protectant media for lyophilization of MA5 were assessed. These findings suggest that Lactococcus lactis MA5 can be an autochthonous probiotic from hybrid catfish, holding promise to be further tested in feeding trials.

The microbial revolution: Unveiling the benefits of vaginal probiotics and prebiotics

Vaginal health is essential to a woman's overall well-being, as abnormalities in vaginal health can lead to a variety of gynaecological disorders, such as urinary tract infections, yeast infections, and bacterial vaginosis. The vaginal microbiome is essential for the prevention of these infections. Disruptions in this microbial ecosystem can significantly impact vaginal health. The concept of utilizing probiotics and prebiotics to stimulate the growth of protective vaginal microbiota has gathered substantial interest in recent years. Probiotics are live micro-organisms that strengthen and restore vaginal microbial balance by lowering pH levels, production of bacteriocins, biofilm disruption, modulation of immune response, and production of hydrogen peroxide (H2O2), consequently combating the development of pathogens. Prebiotics are oligosaccharides that encourage the development of probiotics such as lactobacilli species. Probiotics and prebiotics also have some broader implications for vaginal health, including their role in minimizing the incidence of premature birth, optimizing fertility, managing menopausal symptoms, and preventing vaginal infections. Synbiotics are a combination of probiotics and prebiotics that deliver additional benefits by encouraging the development and activity of beneficial microbes. Furthermore, postbiotics are bioactive compounds derived from probiotic bacteria during fermentation that have immunomodulatory actions and provide an additional layer of protection against vaginal infections. The present study highlights the most prevalent vaginal infections and limitations of existing therapies that influence the vaginal microbiota. The profound consequences of probiotics and prebiotics in women's health, including their role in minimizing the prevalence of vaginal infections and promoting overall vaginal health, as well as advanced therapeutic strategies such as synbiotics and postbiotics, are also discussed. The literature offers significant insights into the mechanism, efficacy, and safety of probiotics and prebiotics to healthcare providers and researchers.

A multispecies bacterial-based direct-fed microbial alleviates Salmonella invasion and supports in vitro epithelial integrity

Managing bacterial infections is of great importance in livestock production, particularly those caused by Salmonella enterica serovars Typhimurium or Dublin, which can impact both animal health and performance, as well as human food safety. Direct-fed microbials (DFM) can support gastrointestinal function and alleviate the potential negative effects of bacterial infections. In the present study, the capacity of a multispecies bacterial-based DFM containing Ligilactobacillus (formerly Lactobacillus) animalis 506, Propionibacterium freudenreichii 507, Bacillus licheniformis 809, and B. subtilis 597 to reduce S. Typhimurium ATCC14028 invasion was investigated using a co-incubation model with the HT29-MTX-E12 cell line (experiment 1). Next, a possible antagonistic effect of the DFM against S. Dublin ATCC 41286 was evaluated using an in vitro agar well diffusion method following a co-incubation of 48 h (experiment 2). At last, a series of experiments were performed to evaluate how different doses (6.25 × 106, 2.50 × 107, or 1.00 × 108 CFU/well) of the DFM would support the integrity of intestinal epithelial cells challenged or not with S. Typhimurium ATCC14028 or hydrogen peroxide under a transepithelial electrical resistance (TEER) assay with Caco-2 cells (experiments 3 and 4). In experiment 1, BDP significantly (P < 0.001) reduced by 90.8% the invasion of S. Typhimurium into HT29-MTX-E12 cells, whereas viability of the potentially harmful bacteria was reduced by 21.0% (P < 0.0001). In experiment 2, the antagonistic properties of BDP towards S. Dublin were confirmed by the detection of a clear inhibition zone (size = 8.6 mm). Lastly, without challenge, the lowest dose of the DFM (6.25 × 106 CFU) provided the greatest support to the cells (treatment × hour; P < 0.0001). However, when the cells were challenged with S. Typhimurium, all doses alleviated the loss of integrity caused by the pathogen (treatment × hour; P < 0.0001). In cells challenged with hydrogen peroxide, the greater dose (1.00 × 108 CFU) supported the cells for a longer period of time (treatment × hour; P < 0.0001). These in vitro findings set the stage for exploring the potential benefits of using a novel DFM as a promising tool and strategy to mitigate S. enterica infections in ruminants and improve animal health, food safety, and public health. Further, in vivo confirmation needs to be developed to validate these preliminary in vitro results.

Probiotics for Prevention and Treatment of Clostridium difficile Infection

Probiotics have been claimed as a valuable tool to restore the balance in the intestinal microbiota following a dysbiosis caused by, among other factors, antibiotic therapy. This perturbed environment could favor the overgrowth of Clostridium difficile, and in fact, the occurrence of C. difficile-associated infections (CDI) is increasing in recent years. In spite of the high number of probiotics able to in vitro inhibit the growth and/or toxicity of this pathogen, its application for treatment or prevention of CDI is still scarce since there are not enough well-defined clinical studies supporting efficacy. Only a few strains, such as Lactobacillus rhamnosus GG and Saccharomyces boulardii, have been studied in more extent. The increasing knowledge about the probiotic mechanisms of action against C. difficile, some of them reviewed here, makes promising the application of these live biotherapeutic agents against CDI. Nevertheless, more effort must be paid to standardize the clinical studies conducted to evaluate probiotic products, in combination with antibiotics, in order to select the best candidate for C. difficile infections.

The impact of probiotic cell-free metabolites in MDR Pseudomonas aeruginosa: antibacterial properties and effect on antibiotic resistance genes expression

There is a significant demand for novel antibacterial agents against multidrug-resistant (MDR) gram-negative bacteria. Recently, probiotics have been noted for their antibacterial properties against various pathogens. This study aimed to investigate the effects of probiotic cell-free supernatants on MDR Pseudomonas aeruginosa. Clinical isolates demonstrating the highest degree of antibiotic resistance were chosen, and the antibacterial effect of probiotic metabolites was evaluated using an agar-well diffusion assay. In addition, the effect of probiotics on the expression of resistance genes was evaluated using real-time PCR. The CFS was assessed using GC-MS to determine the antibacterial compounds. The supernatants inhibited the growth of the isolates (P < 0.0001); however, there was no noticeable difference in the effectiveness of the probiotics. In addition, the supernatants decreased the expression levels of mexD, mexB, mexF, and ampC, and an increase in oprD was observed in some groups. After the assessment of Lactobacillus acidophilus by GC-MS, antibacterial compounds, such as acetamide, nonadecane, 9-methyl, and tetradecane, were determined. Our findings showed that probiotic metabolites can effectively inhibit the growth of MDR P. aeruginosa. Gene expression analysis also revealed that the mechanism of antibacterial action was most likely related to the regulation of efflux pumps.

In-vitro determination of inhibitory effects of probiotic strains on Clostridioides difficile

Commercial probiotic strains inhibited C. difficile, and other Clostridium cultures with zones 14.2-78.9 mm. The highest inhibition was observed with commercial culture on C. difficile ATCC 700057. Organic acids were the leading cause of inhibition. Probiotic cultures may be used as a support culture or through fermented foods for treatment.

Probiotics: insights and new opportunities for Clostridioides difficile intervention

Clostridioides difficile infection (CDI) is a life-threatening disease caused by the Gram-positive, opportunistic intestinal pathogen C. difficile. Despite the availability of antimicrobial drugs to treat CDI, such as vancomycin, metronidazole, and fidaxomicin, recurrence of infection remains a significant clinical challenge. The use of live commensal microorganisms, or probiotics, is one of the most investigated non-antibiotic therapeutic options to balance gastrointestinal (GI) microbiota and subsequently tackle dysbiosis. In this review, we will discuss major commensal probiotic strains that have the potential to prevent and/or treat CDI and its recurrence, reassess the efficacy of probiotics supplementation as a CDI intervention, delve into lessons learned from probiotic modulation of the immune system, explore avenues like genome-scale metabolic network reconstructions, genome sequencing, and multi-omics to identify novel strains and understand their functionality, and discuss the current regulatory framework, challenges, and future directions.

An Overview of the Public Health Challenges in Diagnosing and Controlling Human Foodborne Pathogens

Pathogens found in food are believed to be the leading cause of foodborne illnesses; and they are considered a serious problem with global ramifications. During the last few decades, a lot of attention has been paid to determining the microorganisms that cause foodborne illnesses and developing new methods to identify them. Foodborne pathogen identification technologies have evolved rapidly over the last few decades, with the newer technologies focusing on immunoassays, genome-wide approaches, biosensors, and mass spectrometry as the primary methods of identification. Bacteriophages (phages), probiotics and prebiotics were known to have the ability to combat bacterial diseases since the turn of the 20th century. A primary focus of phage use was the development of medical therapies; however, its use quickly expanded to other applications in biotechnology and industry. A similar argument can be made with regards to the food safety industry, as diseases directly endanger the health of customers. Recently, a lot of attention has been paid to bacteriophages, probiotics and prebiotics most likely due to the exhaustion of traditional antibiotics. Reviewing a variety of current quick identification techniques is the purpose of this study. Using these techniques, we are able to quickly identify foodborne pathogenic bacteria, which forms the basis for future research advances. A review of recent studies on the use of phages, probiotics and prebiotics as a means of combating significant foodborne diseases is also presented. Furthermore, we discussed the advantages of using phages as well as the challenges they face, especially given their prevalent application in food safety.

Recovery of Potential Starter Cultures and Probiotics from Fermented Sorghum (Ting) Slurries

Fermented foods are thought to provide a source of probiotics that promote gut health. Consequently, isolation and characterization of fermented food strains and their applications in a controlled fermentation process or as probiotics present a new facet in this area of research. Therefore, the current study sought to identify dominant strains in sorghum-fermented foods (ting) and characterize their probiotic potential in vitro. Recovered isolates were identified as Lactobacillus helveticus, Lactobacillus amylolyticus, Lacticaseibacillus paracasei, Lacticaseibacillus paracasei subsp paracasei, Lactiplantibacillus plantarum, Levilactobacillus brevis, Loigolactobacillus coryniformis and Loigolactobacillus coryniformis subsp torquens based on the their 16S rRNA sequences. Increased biomass was noted in seven out of nine under a low pH of 3 and a high bile concentration of 2% in vitro. Bactericidal activities of isolated LABs presented varying degrees of resistance against selected pathogenic bacteria ranging between (1.57 to 41 mm), (10 to 41 mm), and (11.26 to 42 mm) for Salmonella typhimurium ATTC 14028, Staphylococcus aureus ATTC 6538 and Escherichia coli ATTC8739, respectively. Ampicillin, erythromycin, mupirocin, tetracycline and chloramphenicol were able to inhibit growth of all selected LABs. Thus, isolates recovered from ting partially satisfy the potential candidacy for probiotics by virtue of being more tolerant to acid and bile, antibacterial activity and antibiotic resistance.

Human milk oligosaccharides, antimicrobial drugs, and the gut microbiota of term neonates: observations from the KOALA birth cohort study

The infant gut microbiota affects childhood health. This pioneer microbiota may be vulnerable to antibiotic exposures, but could be supported by prebiotic oligosaccharides found in breast milk and some infant formulas. We sought to characterize the effects of several exposures on the neonatal gut microbiota, including human milk oligosaccharides (HMOs), galacto-oligosaccharides (GOS), and infant/maternal antimicrobial exposures. We profiled the stool microbiota of 1023 one-month-old infants from the KOALA Birth Cohort using 16S rRNA gene amplicon sequencing. We quantified 15 HMOs in breast milk from the mothers of 220 infants, using high-performance liquid chromatography-mass spectrometry. Both breastfeeding and antibiotic exposure decreased gut microbial diversity, but each was associated with contrasting shifts in microbiota composition. Other factors associated with microbiota composition included C-section, homebirth, siblings, and exposure to animals. Neither infant exposure to oral antifungals nor maternal exposure to antibiotics during pregnancy were associated with infant microbiota composition. Four distinct groups of breast milk HMO compositions were evident, corresponding to maternal Secretor status and Lewis group combinations defined by the presence/absence of certain fucosylated HMOs. However, we found the strongest evidence for microbiota associations between two non-fucosylated HMOs: 6'-sialyllactose (6'-SL) and lacto-N-hexaose (LNH), which were associated with lower and higher relative abundances of Bifidobacterium, respectively. Among 111 exclusively formula-fed infants, the GOS-supplemented formula was associated with a lower relative abundance of Clostridium perfringens. In conclusion, the gut microbiota is sensitive to some prebiotic and antibiotic exposures during early infancy and understanding their effects could inform future strategies for safeguarding a health-promoting infant gut microbiota.

Potential Probiotic Properties of Exopolysaccharide-Producing Lacticaseibacillus paracasei EPS DA-BACS and Prebiotic Activity of Its Exopolysaccharide

Exopolysaccharide (EPS)-producing Lacticaseibacillus paracasei EPS DA-BACS was isolated from healthy human feces and its probiotic properties, as well as the structure and prebiotic activity of the EPS from this strain were examined. EPS from L. paracasei EPS DA-BACS had a ropy phenotype, which is known to have potential health benefits and is identified as loosely cell-bounded glucomannan-type EPS with a molecular size of 3.7 × 106 Da. EPS promoted the acid tolerance of L. paracasei EPS DA-BACS and provided cells with tolerance to gastrointestinal stress. The purified EPS showed growth inhibitory activity against Clostridium difficile. L. paracasei EPS DA-BACS cells completely inhibited the growth of Bacillus subtilis, Pseudomonas aeruginosa, and Aspergillus brasiliensis, as well as showed high growth inhibitory activity against Staphylococcus aureus and Escherichia coli. Treatment of lipopolysaccharide-stimulated RAW 264.7 cells with heat-killed L. paracasei EPS DA-BACS cells led to a decrease in the production of nitric oxide, indicating the anti-inflammatory activity of L. paracasei EPS DA-BACS. Purified EPS promoted the growth of Lactobacillus gasseri, Bifidobacterium bifidum, B. animalis, and B. faecale which showed high prebiotic activity. L. paracasei EPS DA-BACS harbors no antibiotic resistance genes or virulence factors. Therefore, L. paracasei EPS DA-BACS exhibits anti-inflammatory and antimicrobial activities with high gut adhesion ability and gastrointestinal tolerance and can be used as a potential probiotic.

Effects of Treatment with Lactobacilli on Necrotic Enteritis in Broiler Chickens

Growth promoter antibiotics have been commonly used for the control of necrotic enteritis (NE) in broilers for decades. However, due to a ban on the use of these antibiotics, alternatives such as probiotics have been tested widely for NE control. The present study tested the efficacy of four different species of lactobacilli (two isolates of Lactobacillus johnsonii and one of Ligilactobacillus (L.) salivarius, Limosilactobacillus (L.) reuteri, and L. crispatus) against NE. Day-old male broiler chickens were divided into six groups and orally inoculated with 1 × 10⁷ or 1 × 10⁸ colony-forming units (CFU) of lactobacilli on 1, 7, 14, and 20 days of age. While negative and positive control groups did not receive lactobacilli, the latter was challenged with Clostridium perfringens (CP). Chickens, at 21 days old, were challenged for 3 days with 3 × 10⁸ CFU of a virulent strain of CP. Tissues were collected for immune system gene expression, immunophenotyping, intestinal histomorphometry, and microbiota analysis. Lactobacilli inoculation conferred partial protection in chickens against NE, marked by lowered lesion scores and improved villus:crypt ratio. Immunomodulatory effects were demonstrated by the significant alteration of interferon (IFN)-γ, interleukin (IL)-1β, IL-2, IL-12p35, IL-17, and transforming growth factor beta (TGF-β) gene transcription in the duodenum and jejunum as well as subtle changes in the frequency of CD8 + T cells and B cells in the cecal tonsil of the treated chickens. Microbiota analysis showed increased levels of some bacterial phyla including Actinobacteria, Lactobacillaceae, and Firmicutes. In conclusion, these findings suggest that the use of certain lactobacilli can reduce NE severity and modulate immune responses and intestinal microbiota composition in chickens.

Reduction of Pathogens in Feces and Lymph Nodes Collected from Beef Cattle Fed Lactobacillus salivarius (L28), Lactobacillus acidophilus (NP51) and Propionibacterium freudenreichii (NP28), Commercially Available Direct-Fed Microbials

The purpose of the study was to evaluate the prevalence and concentration of foodborne pathogens in the feces and peripheral lymph nodes (PLNs) of beef cattle when supplemented with direct-fed microbials (DFMs) in feedlots. Fecal samples were collected from the pen floors over a 5-month period at three different feedlots in a similar geographical location in Nebraska, where each feed yard represented a treatment group: (i.) control: no supplement, (ii.) Bovamine Defend: supplemented with NP51 and NP24 at a target dose of 9 log₁₀CFU/g/head/day, and (iii.) Probicon: supplemented with L28 at a target dose of 6 log₁₀CFU/g/head/day. Each fecal sample was tested for the prevalence of E. coli O157:H7 and Salmonella, and concentration of E. coli O157:H7, Enterobacteriaceae and Clostridium perfringens. Cattle were harvested and PLNs were collected on the harvest floor. Real-time Salmonella PCR assays were performed for each PLN sample to determine Salmonella presence. The cattle supplemented with both DFMs had reduced foodborne pathogens in fecal samples, but feces collected from the pens housing the cattle supplemented with Probicon consistently had significantly less E. coli O157:H7 and Salmonella prevalence as well as a lower C. perfringens concentration. While DFMs do not eliminate foodborne pathogens in fecal shedding and PLNs, the use of DFMs as a pre-harvest intervention allows for an effective way to target multiple pathogens reducing the public health risks and environmental dissemination from cattle.

Efficacy of Two Probiotic Products Fed Daily to Reduce Clostridium perfringens-Based Adverse Health and Performance Effects in Dairy Calves

Clostridium perfringens is a spore-forming, anaerobic bacterium which produces toxins and exoenzymes that cause disease in calves, especially necro-hemorrhagic enteritis-associated diarrhea often resulting in death. Clostridium infections are currently being treated with antibiotics, but even with the prudent administration of antibiotics, there are significant rates of recurrence. Probiotics, an alternative to antibiotics, are commonly employed to prevent clostridial infections. The objectives of our study were to demonstrate that two commercially available products, when used as daily, direct-fed microbials, are effective in reducing adverse effects of an experimentally induced C. perfringens infection in dairy calves. We conducted a single site efficacy study with masking using a randomized design comprising 10 calves allocated to 3 treatment groups (probiotic 1, probiotic 2, and control). The procedures such as general health scores, body weight, blood samples, and fecal sample collections were done followed by experimental challenge of calves with C. perfringens. Daily feeding of L. animalis LA51 and P. freudenreichii PF24 without or with Bacillus lichenformis CH200 and Bacillus subtilis CH201, before, during and after an oral challenge of C. perfringens significantly reduced the incidence and severity of diarrhea while improving general impression and appearance scores of calves. Most notably, survival of calves in the two probiotic-fed groups was significantly higher than for control calves and further substantiates the potential economic and health benefits of feeding effective probiotics.

The Effects of Bacillus licheniformis—Fermented Products on the Microbiota and Clinical Presentation of Cats with Chronic Diarrhea

Bacillus licheniformis-fermented products (BLFP) are probiotics with antibacterial, antiviral, and anti-inflammatory properties that can improve growth performance. This study aimed to compare the fecal microbiota of diarrheal cats with chronic diarrhea (n = 8) with that of healthy cats (n = 4) from the same household using next-generation sequencing, and evaluate the effectiveness of oral administration of BLFP in relieving clinical signs and altering the intestinal microbiota in diarrheal cats. Six out of eight diarrheal cats showed clinical improvement after BLFP administration for 7 days, and the stool condition of the other two was normal. A higher Firmicutes/Bacteroidetes ratio was noted in the feces of diarrheal cats without clinical improvement as compared with those in the healthy cats and in the diarrheal cats with clinical improvement after receiving BLFP. The phylum Bacteroidetes and class Bacteroidia decreased significantly in diarrheal cats regardless of BLFP administration. Blautia spp., Ruminococcus torques, and Ruminococcus gnavus, which belong to the Clostridium cluster XIVa and have been reported as beneficial to intestinal health, increased significantly in feces after treatment. Furthermore, Clostridium perfringens also significantly decreased in diarrheal cats after BLFP administration. Overall, BLFP could be a potential probiotic to relieve gastrointestinal symptoms and improve fecal microbiota in cats with chronic diarrhea.

Probiotics as Alternatives to Antibiotics for the Prevention and Control of Necrotic Enteritis in Chickens

Necrotic enteritis (NE) in poultry is an economically important disease caused by Clostridium perfringens type A bacteria. A global trend on restricting the use of antibiotics as feed supplements in food animal production has caused a spike in the NE incidences in chickens, particularly in broiler populations. Amongst several non-antibiotic strategies for NE control tried so far, probiotics seem to offer promising avenues. The current review focuses on studies that have evaluated probiotic effects on C. perfringens growth and NE development. Several probiotic species, including Lactobacillus, Enterococcus, Bacillus, and Bacteroides bacteria as well as some yeast species have been tested in chickens against C. perfringens and NE development. These findings have shown to improve bird performance, reduce C. perfringens colonization and NE-associated pathology. The underlying probiotic mechanisms of NE control suggest that probiotics can help maintain a healthy gut microbial balance by modifying its composition, improve mucosal integrity by upregulating expression of tight-junction proteins, and modulate immune responses by downregulating expression of inflammatory cytokines. Collectively, these studies indicate that probiotics can offer a promising platform for NE control and that more investigations are needed to study whether these experimental probiotics can effectively prevent NE in commercial poultry operational settings.

Effect of Porcine Clostridium perfringens on Intestinal Barrier, Immunity, and Quantitative Analysis of Intestinal Bacterial Communities in Mice

Clostridium perfringens (C. perfringens) is one of the main pathogens which can cause a range of histotoxic and enteric diseases in humans or animals (pigs, or broilers). The Centers for Disease Control and Prevention (CDC) estimates these bacteria cause nearly 1 million illnesses in the United States every year. For animal husbandry, necrotizing enteritis caused by C. perfringens can cost the global livestock industry between $2 billion and $6 billion per year. C. perfringens-infected animals can be isolated for its identification and pathology. A suitable animal model is one of the essential conditions for studying the disease pathogenesis. In previous studies, mice have been used as subjects for a variety of Clostridium perfringens toxicity tests. Thus, this study was designed to build a mouse model infected porcine C. perfringens which was isolated from the C.perfringens-infected pigs. A total of 32 6-week-old male C57BL/6 mice were randomly divided into four groups. Control group was orally administrated with PBS (200 μL) on day 0. Low group, Medium group, and High group were gavaged with 200 ul of PBS resuspension containing 8.0 × 10⁷ CFU, 4.0 × 10⁸ CFU, and 2.0 × 10⁹ CFU, respectively. We examined growth performance, immune status, intestinal barrier integrity, apoptosis-related genes expression, and copies of C. perfringens in mice. The results showed that the growth performance declined and intestinal structure was seriously damaged in High group. Meanwhile, pro-inflammatory factors (IL-1β, TNF-α, and IL-6) were significantly increased (P < 0.05) in High group compared to other groups. The tight junctions and pro-apoptosis related genes' expression significantly decreased (P < 0.05) in High group, and high dose caused a disruption of intestinal villi integrity and tissue injury in the jejunum of mice. In addition, the enumerations of C. perfringens, Escherichia coli, and Lactobacillus explained why the gut of High group mice was seriously damaged, because the C. perfringens and Escherichia coli significantly enriched (P < 0.05), and Lactobacillus dramatically decreased (P < 0.05). Overall, our results provide an experimental and theoretical basis for understanding the pathogenesis and exploring the effects of porcine C. perfringens on mice.

Proteobacteria and Firmicutes Secreted Factors Exert Distinct Effects on Pseudomonas aeruginosa Infection under Normoxia or Mild Hypoxia

Microbiota may alter a pathogen's virulence potential at polymicrobial infection sites. Here, we developed a multi-modal Drosophila assay, amenable to the assessment of human bacterial interactions using fly survival or midgut regeneration as a readout, under normoxia or mild hypoxia. Deploying a matrix of 12 by 33 one-to-one Drosophila co-infections via feeding, we classified bacterial interactions as neutral, synergistic, or antagonistic, based on fly survival. Twenty six percent of these interactions were antagonistic, mainly occurring between Proteobacteria. Specifically, Pseudomonas aeruginosa infection was antagonized by various Klebsiella strains, Acinetobacter baumannii, and Escherichia coli. We validated these interactions in a second screen of 7 by 34 one-to-one Drosophila co-infections based on assessments of midgut regeneration, and in bacterial co-culture test tube assays, where antagonistic interactions depended on secreted factors produced upon high sugar availability. Moreover, Enterococci interacted synergistically with P. aeruginosa in flies and in test tubes, enhancing the virulence and pyocyanin production by P. aeruginosa. However, neither lactic acid bacteria nor their severely hypoxic culture supernatants provided a survival benefit upon P. aeruginosa infection of flies or mice, respectively. We propose that at normoxic or mildly hypoxic sites, Firmicutes may exacerbate, whereas Proteobacteria secreted factors may ameliorate, P. aeruginosa infections.

Bioengineered Probiotics: Synthetic Biology Can Provide Live Cell Therapeutics for the Treatment of Foodborne Diseases

The rising prevalence of antibiotic resistant microbial pathogens presents an ominous health and economic challenge to modern society. The discovery and large-scale development of antibiotic drugs in previous decades was transformational, providing cheap, effective treatment for what would previously have been a lethal infection. As microbial strains resistant to many or even all antibiotic drug treatments have evolved, there is an urgent need for new drugs or antimicrobial treatments to control these pathogens. The ability to sequence and mine the genomes of an increasing number of microbial strains from previously unexplored environments has the potential to identify new natural product antibiotic biosynthesis pathways. This coupled with the power of synthetic biology to generate new production chassis, biosensors and “weaponized” live cell therapeutics may provide new means to combat the rapidly evolving threat of drug resistant microbial pathogens. This review focuses on the application of synthetic biology to construct probiotic strains that have been endowed with functionalities allowing them to identify, compete with and in some cases kill microbial pathogens as well as stimulate host immunity. Weaponized probiotics may have the greatest potential for use against pathogens that infect the gastrointestinal tract: Vibrio cholerae, Staphylococcus aureus, Clostridium perfringens and Clostridioides difficile. The potential benefits of engineered probiotics are highlighted along with the challenges that must still be met before these intriguing and exciting new therapeutic tools can be widely deployed.

Lactobacillus spp. for Gastrointestinal Health: Current and Future Perspectives

In recent decades, probiotic bacteria have become increasingly popular as a result of mounting scientific evidence to indicate their beneficial role in modulating human health. Although there is strong evidence associating various Lactobacillus probiotics to various health benefits, further research is needed, in particular to determine the various mechanisms by which probiotics may exert these effects and indeed to gauge inter-individual value one can expect from consuming these products. One must take into consideration the differences in individual and combination strains, and conditions which create difficulty in making direct comparisons. The aim of this paper is to review the current understanding of the means by which Lactobacillus species stand to benefit our gastrointestinal health.

Bifidobacterium spp. as functional foods: A review of current status, challenges, and strategies

Members of Bifidobacterium are among the first microbes to colonize the human intestine naturally, their abundance and diversity in the colon are closely related to host health. Recently, the gut microbiota has been gradually proven to be crucial mediators of various metabolic processes between the external environment and the host. Therefore, the health-promoting benefits of Bifidobacterium spp. and their applications in food have gradually been widely concerned. The main purpose of this review is to comprehensively introduce general features, colonization methods, and safety of Bifidobacterium spp. in the human gut, highlighting its health benefits and industrial applications. On this basis, the existing limitations and scope for future research are also discussed. Bifidobacteria have beneficial effects on the host's digestive system, immune system, and nervous system. However, the first prerequisite for functioning is to have enough live bacteria before consumption and successfully colonize the colon after ingestion. At present, strain breeding, optimization (e.g., selecting acid and bile resistant strains, adaptive evolution, high cell density culture), and external protection technology (e.g., microencapsulation and protectants) are the main strategies to address these challenges in food application.

Balancing reactive oxygen species generation by rebooting gut microbiota

Reactive oxygen species (ROS; free radical form O₂ ^•‾ , superoxide radical; OH^• , hydroxyl radical; ROO^• , peroxyl; RO^• , alkoxyl and non-radical form ¹ O₂ , singlet oxygen; H₂ O₂ , hydrogen peroxide) are inevitable companions of aerobic life with crucial role in gut health. But, overwhelming production of ROS can cause serious damage to biomolecules. In this review, we have discussed several sources of ROS production that can be beneficial or dangerous to the human gut. Microorganisms, organelles and enzymes play crucial role in ROS generation, where, NOX1 is the main intestinal enzyme, which produce ROS in the intestine epithelial cells. Previous studies have reported that probiotics play significant role in gut homeostasis by checking the ROS generation, maintaining the antioxidant level, immune system and barrier protection. With current knowledge, we have critically analyzed the available literature and presented the outcome in the form of bubble maps to suggest the probiotics that help in controlling the ROS-specific intestinal diseases, such as inflammatory bowel disease (IBD) and colon cancer. Finally, it has been concluded that rebooting of the gut microbiota with probiotics, postbiotics or fecal microbiota transplantation (FMT) can have crucial implications in the structuring of gut communities for the personalized management of the gastrointestinal (GI) diseases.

COVID-19 and gut dysbiosis, understanding the role of probiotic supplements in reversing gut dysbiosis and immunity

In December 2019, an outbreak of novel beta-coronavirus started in Wuhan, China, spread globally as coronavirus disease 2019 (COVID-19) pandemic and is still underway. The causative agent for COVID-19 identified as a novel strain of beta coronavirus named nSARS-CoV-2. The nSARS-CoV-2 primarily targets the respiratory tract and results in severe acute respiratory distress (ARDS), leading to the collapse of the respiratory tract. The virus internalizes primarily via ACEII receptor, and many tissues reported a significant level of expression of ACEII receptor including lungs, hearts, kidneys, and gastrointestinal tract. The clinical manifestations of COVID-19 are diverse, but growing evidence suggests that gut dysbiosis is one of them and poses a threat to native immunity. The human microbial ecology plays a vital role in human physiology, including building immunity. The gastrointestinal tract (GIT) habitats trillions of beneficial microbes’ precisely bacterial species synchronize with human physiology and remain symbiotic. On the contrary, harmful microbiota seeks an opportunity to break the equilibrium failure of balance between beneficial and detrimental human gut microbiota results in impaired physiology and immunity. The grown research evidence demonstrated that infection caused by the nSARS-CoV-2 result in moderate to severe diarrheal outcomes. The diarrheal conditions in COVID-19 patients are due to alteration of gut microbial ecology. The management of COVID-19 requires specialized therapeutics along with a series of nutraceuticals. Probiotics remain vital nutrient supplements in COVID-19 management, offer relief in diarrhea and improve/restore immunity. This study uses available data/findings to emphasize an association between COVID-19 and gut dysbiosis. The study also provides a scientific basis of impaired immunity during gut dysbiosis in COVID-19 and how probiotics help restore and improve impaired immunity and diarrhea.

Gut microbiota: a target for intervention in obesity

INTRODUCTION

Obesity is a major public health concern with an increasing prevalence. Recent studies suggest an influence of gastrointestinal microbiota on obesity. Consequently, microbiota restoration therapies are being considered as potential management. We present data on microbiome markers and the future of microbiota therapeutics for obesity.

AREAS COVERED

We summarize the pathogenesis of obesity, relationship between gut microbiota and obesity, use of microbiota-based therapies. Data were gathered by a literature search of articles in PubMed from the date of inception till August 2020. Keywords used were 'gut microbiota,' 'gut microbiome,' 'microbiota,' 'microbiome,' 'obesity,' and 'obesity and fecal microbiota transplantation' as MeSH terms.

EXPERT OPINION

The direct relationship of gut microbiota in causing obesity needs exploration. Because of the scarcity of human studies, the utility of microbiota-based therapies as treatment remains uncertain and the use of microbiome restoration for obesity should be restricted to research settings. To evaluate the efficacy of microbiota restoration, studies using these therapies as an adjunct with diet and lifestyle should be conducted. Once relationships between bacterial strains and the human metabolic profile are determined, these strains could be cultured for transfer to obese patients. Such advancement could help in tailoring personalized therapies for obese persons.

Tripartite relationship between gut microbiota, intestinal mucus and dietary fibers: towards preventive strategies against enteric infections

The human gut is inhabited by a large variety of microorganims involved in many physiological processes and collectively referred as to gut microbiota. Disrupted microbiome has been associated with negative health outcomes and especially could promote the onset of enteric infections. To sustain their growth and persistence within the human digestive tract, gut microbes and enteric pathogens rely on two main polysaccharide compartments, namely dietary fibers and mucus carbohydrates. Several evidences suggest that the three-way relationship between gut microbiota, dietary fibers and mucus layer could unravel the capacity of enteric pathogens to colonise the human digestive tract and ultimately lead to infection. The review starts by shedding light on similarities and differences between dietary fibers and mucus carbohydrates structures and functions. Next, we provide an overview of the interactions of these two components with the third partner, namely, the gut microbiota, under health and disease situations. The review will then provide insights into the relevance of using dietary fibers interventions to prevent enteric infections with a focus on gut microbial imbalance and impaired-mucus integrity. Facing the numerous challenges in studying microbiota-pathogen-dietary fiber-mucus interactions, we lastly describe the characteristics and potentialities of currently available in vitro models of the human gut.

Inhibition of Quinolone- and Multi-Drug-Resistant Clostridioides Difficile Strains by Multi Strain Synbiotics-An Option for Diarrhea Management in Nursing Facilities

Diarrhea is a common problem in nursing homes. A survey among nursing facilities in Poland was used to characterize diarrhea outbreaks, the burden caused for residents and caregivers and the employed measures. Survey results confirmed that diarrhea is a common problem in nursing homes and in most cases affects groups of residents. The related burden is high or very high for 27% of residents and 40% of caregivers. In 80% of nursing facilities pro or synbiotics are part of the measures used to manage diarrhea. Administration of these kinds of products has been suggested for the management of diarrhea, especially in cases caused by Clostridioides (C.) difficile. C. difficile is one of many potential causes for diarrhea, but is of particular concern for nursing homes because it is responsible for a large proportion of diarrhea outbreaks and is often caused by multi-drug resistant strains. In vitro inhibition of a quinolone-resistant and a multi-drug resistant C. difficile strain was used to evaluate the growth inhibitory effects of commonly used products containing probiotic microorganisms. Growth of both strains was best inhibited by multi-strain synbiotic preparations. These findings suggest that multi-strain synbiotics can be considered as an interventional option for diarrhea caused by C. difficile.

Changes in gut microbiota composition and diversity associated with post-cholecystectomy diarrhea

BACKGROUND

Post-cholecystectomy diarrhea (PCD) frequently occurs in patients following gallbladder removal. PCD is part of the post-cholecystectomy (PC) syndrome, and is difficult to treat. After cholecystectomy, bile enters the duodenum directly, independent of the timing of meals. The interaction between the bile acids and the intestinal microbes is changed. Therefore, the occurrence of PCD may be related to the change in microbiota. However, little is known about the relationship between the gut microbiota and PCD.

AIM

To better understand the role of the gut microbiota in PCD patients.

METHODS

Fecal DNA was isolated. The diversity and profiles of the gut microbiota were analyzed by performing high-throughput 16S rRNA gene sequencing. The gut microbiota were characterized in a healthy control (HC) group and a PC group. Subsequently, the PC group was further divided into a PCD group and a post-cholecystectomy non-diarrhea group (PCND) according to the patients' clinical symptoms. The composition, diversity and richness of microbial communities were determined and compared.

RESULTS

In the PC and HC groups, 720 operational taxonomic units (OTUs) were identified. The PC group had fewer OTUs than the HC group. β-diversity was decreased in the PC group. This indicated decreased microbial diversity in the PC group. Fifteen taxa with differential abundance between the HC and PC groups were identified. In the PCD group compared to the PCND group, significant decreases in microbial diversity, Firmicutes/Bacteroidetes ratio, and richness of probiotic microbiota (Bifidobacterium and Lactococcus), and an increase in detrimental microbiota (Prevotella and Sutterella) were observed. Moreover, a negative correlation was found between Prevotella and Bifidobacterium. Using a Kyoto Encyclopedia of Genes and Genomes functional analysis, it was found that the abundances of gut microbiota involved in lipid metabolism pathways were markedly lower in the PCD group compared to the PCND group.

CONCLUSION

This study demonstrated that gut dysbiosis may play a critical role in PCD, which provides new insights into therapeutic options for PCD patients.

Update of Probiotics in Human World: A Nonstop Source of Benefactions till the End of Time

Lactic acid bacteria (LAB) are known for their biotechnological potential. Moreover, LAB are distinguished by amazing criteria: Adjusting the intestinal environment, inhibiting pathogenic microbes in the gastrointestinal tract, ability to reduce pathogen adhesion activity, improving the balance of the microbiota inside the intestine, capabilities of regulating intestinal mucosal immunity, and maintaining intestinal barrier function. The escalating number of research and studies about beneficial microorganisms and their impact on promoting health has attracted a big interest in the last decades. Since antiquity, various based fermented products of different kinds have been utilized as potential probiotic products. Nevertheless, the current upsurge in consumers' interest in bioalternatives has opened new horizons for the probiotic field in terms of research and development. The present review aims at shedding light on the world of probiotics, a continuous story of astonishing success in various fields, in particular, the biomedical sector and pharmaceutical industry, as well as to display the importance of probiotics and their therapeutic potential in purpose to compete for sturdy pathogens and to struggle against diseases and acute infections. Shadows and future trends of probiotics use are also discussed.

Selection and Characterization of Staphylococcus hominis subsp. hominis WiKim0113 Isolated from Kimchi as a Starter Culture for the Production of Natural Pre-converted Nitrite

Synthetic nitrite is considered an undesirable preservative for meat products; thus, controlling synthetic nitrite concentrations is important from the standpoint of food safety. We investigated 1,000 species of microorganisms from various kimchi preparations for their potential use as a starter culture for the production of nitrites. We used 16S rRNA gene sequence analysis to select a starter culture with excellent nitrite and nitric oxide productivity, which we subsequently identified as Staphylococcus hominis subspecies hominis WiKim0113. That starter culture was grown in NaCl (up to 9%; w/v) at 10°C–40°C; its optimum growth was observed at 30°C at pH 4.0–10.0. It exhibited nonproteolytic activity and antibacterial activity against Clostridium perfringens, a bacterium that causes food poisoning symptoms. Analysis of Staphylococcus hominis subspecies hominis WiKim0113 with an API ZYM system did not reveal the presence of β-glucuronidase, and tests of the starter culture on 5% (v/v) sheep blood agar showed no hemolytic activity. Our results demonstrated the remarkable stability of coagulase-negative Staphylococcus hominis subspecies hominis WiKim0113, especially in strain negative for staphylococcal enterotoxins and sensitive to clinically relevant antibiotics. Moreover, Staphylococcus hominis subspecies hominis WiKim0113 exhibited a 45.5% conversion rate of nitrate to nitrite, with nitrate levels reduced to 25% after 36 h of culturing in the minimal medium supplemented with nitrate (200 ppm). The results clearly demonstrated the safety and utility of Staphylococcus hominis subspecies hominis WiKim0113, and therefore its suitability as a starter culture.

Dietary supplementation with Bacillus subtilis DSM 32315 alters the intestinal microbiota and metabolites in weaned piglets

AIM

The study was conducted to investigate the effects of dietary Bacillus subtilis (BS) DSM 32315 on the intestinal microbiota composition and metabolites of weaned pigs.

METHODS AND RESULTS

Sixty-four piglets were allocated to two groups (control and BS), each group including eight replicates with four piglets. Dietary BS DSM 32315 increased (P < 0·05) the abundances of jejunal Leucobacter and Cupriavidus, ileal Thermus, Coprococcus and Bifidobacterium, as well as colonic Succiniclasticum; and increased the concentrations of ileal straight-chain fatty acids, colonic propionate, branched-chain fatty acids (BCFAs), and tyramine, but decreased (P < .05) the colonic indole concentration. The ileal and colonic microbial community structure tended to cluster into two groups. LEfSe analysis identified five microbial biomarkers in jejunum and eight biomarkers in ileum in the BS group, and three biomarkers in colon in the control group. The ileal Bifidobacterium abundance was positively correlated (P < 0·05) with isovalerate concentration, while the colonic Actinobacteria and Lactobacillus abundances were negatively correlated (P < 0·05) with indole concentration.

CONCLUSION

These findings suggest that dietary supplementation with BS DSM 32315 could alter the diversity, composition, and metabolites of intestinal microbiota in weaned piglets.

SIGNIFICANCE AND IMPACT OF THE STUDY

Weaned piglets are often accompanied with impaired gastrointestinal tract and intestinal disorder affecting their growth. This study demonstrated that dietary BS DSM 32315 presented a beneficial role in gut health via regulating intestinal microbiota composition and metabolites.

The mechanisms and safety of probiotics against toxigenic clostridium difficile

INTRODUCTION

Toxigenic Clostridium difficile (C. difficile) is the main cause of antibiotic-associated diarrhea and can induce pseudomembranous colitis and infrequent toxic megacolon, which are potentially fatal. The standard antibiotic therapy for C. difficile infection (CDI) is limited by antibiotics' broad spectrum and further disruptive effects on indigenous microbiota. Probiotics may offer a prospective and alternative strategy for the prevention and treatment of CDI.

AREAS COVERED

In this article, the mechanisms implying the probiotic effect against C. difficile and the safety profile highlighting the patient groups with inappropriate application of probiotics were reviewed from 2015 to 2020.

EXPERT OPINION

Although many strains with ability against C. difficile have been reported, the usage of probiotics for CDI prevention and/or treatment is scarce since the number of clinical trials is not sufficient to prove probiotics' efficacy and safety in CDI treatment, especially for premature infant and immunocompromised patient. Especially, there are few well-defined clinical studies supporting safety of probiotics for CDI. A few strains from Lactobacillus and Saccharomyces genus have been studied more extensively than other probiotic strains through clinical trials for CDI. Thus, more clinical intervention studies regarding the benefit and the comprehensive safety assessments of probiotics for CDI are needed.

Microbiota in vitro modulated with polyphenols shows decreased colonization resistance against Clostridioides difficile but can neutralize cytotoxicity

While the knowledge on gut microbiota - C. difficile interactions has improved over the years, the understanding of the underlying mechanisms providing colonization resistance as well as preventative measures against the infection remain incomplete. In this study the antibiotic clindamycin and polyphenol extracts from pomegranate and blueberries were used individually and in combination to modulate fecal microbial communities in minibioreactor arrays (MBRA). Modulated communities were inoculated with C. difficile (ribotype 027). Subsequent 7-day periodical monitoring included evaluation of C. difficile growth and activity of toxins TcdA and TcdB as well as analysis of MBRA bacterial community structure (V3V4 16 S metagenomics). Polyphenols affected multiple commensal bacterial groups and showed different synergistic and antagonistic effects in combination with clindamycin. Exposure to either clindamycin or polyphenols led to the loss of colonization resistance against C. difficile. The successful growth of C. difficile was most significantly correlated with the decrease in Collinsella and Lachnospiraceae. Additionally, we demonstrated that Clostridium sporogenes decreased the activity of both C. difficile toxins TcdA and TcdB. The feature was shown to be common among distinct C. sporogenes strains and could potentially be applicable as a non-antibiotic agent for the alleviation of C. difficile infection.

In-Vitro Growth Inhibition of Bacterial Pathogens by Probiotics and a Synbiotic: Product Composition Matters

A variety of activities potentially contribute to the beneficial effects of probiotic bacteria observed in humans. Among these is a direct inhibition of the growth of pathogenic bacteria in the gut. The present study characterizes head-to-head the in-vitro pathogen growth inhibition of clinically relevant infectious bacterial strains by different types of probiotics and a synbiotic. In-vitro growth inhibition of Escherichia (E.) coli EPEC, Shigella (Sh.) sonnei, Salmonella (S.) typhimurium, Klebsiella (K.) pneumoniae and Clostridioides (C.) difficile were determined. Investigated products were a yeast mono strain probiotic containing Saccharomyces (Sac.) boulardii, bacterial mono strain probiotics containing either Lactobacillus (L.) rhamnosus GG or L. reuteri DSM 17938, a multi strain probiotic containing three L. rhamnosus strains (E/N, Oxy, Pen), and a multi strain synbiotic containing nine different probiotic bacterial strains and the prebiotic fructooligosaccharides (FOS). Inhibition of pathogens was moderate by Sac. boulardii and L. rhamnosus GG, medium by L. reuteri DSM 17938 and the L. rhamnosus E/N, Oxy, Pen mixture and strong by the multi strain synbiotic. Head-to-head in-vitro pathogen growth inhibition experiments can be used to differentiate products from different categories containing probiotic microorganisms and can support the selection process of products for further clinical evaluation.

Rapid in Vitro Assessment of Clostridioides difficile Inhibition by Probiotics Using Dielectrophoresis to Quantify Cell Structure Alterations

Clostridioides difficile (C. difficile) infection (CDI) is the primary cause of nosocomial antibiotic-associated diarrhea, with high recurrence rates following initial antibiotic treatment regimens. Restoration of the host gut microbiome through probiotic therapy is under investigation to reduce recurrence. Current in vitro methods to assess C. difficile deactivation by probiotic microorganisms are based on C. difficile growth inhibition, but the cumbersome and time-consuming nature of the assay limits the number of assessed permutations. Phenotypic alterations to the C. difficile cellular structure upon interaction with probiotics can potentially enable rapid assessment of the inhibition without the need for extended culture. Because supernatants from cultures of commensal microbiota reflect the complex metabolite milieu that deactivates C. difficile, we explore coculture of C. difficile with an optimal dose of supernatants from probiotic culture to speed growth inhibition assays and enable correlation with alterations to its prolate ellipsoidal structure. Based on sensitivity of electrical polarizability to C. difficile cell shape and subcellular structure, we show that the inhibitory effect of Lactobacillus spp. supernatants on C. difficile can be determined based on the positive dielectrophoresis level within just 1 h of culture using a highly toxigenic strain and a clinical isolate, whereas optical and growth inhibition measurements require far greater culture time. We envision application of this in vitro coculture model, in conjunction with dielectrophoresis, to rapidly screen for potential probiotic combinations for the treatment of recurrent CDI.

Bacteria producing antimicrobials against Clostridium difficile isolated from human stool

Clostridium difficile infection (CDI) is a common cause of morbidity and mortality in hospitalized patients worldwide. The major problem facing current treatment is multiple recurrences, prompting the need for alternative therapies. In this study we isolated bacterial species, from Egyptian individuals' stool, with antimicrobial activity against clinical isolates of C. difficile and tried to examine the nature of the produced antimicrobials. In vitro antibacterial activity against C. difficile was initially screened in 123 fecal samples cultures using an agar overlay method. The isolates with antimicrobial activity against C. difficile in addition to Clostridium isolates were identified using partial 16S rDNA gene sequencing analysis. The isolates acting against C. difficile belonged to Lactobacillus, Enterococcus and Clostridium genera. The concentrated cell-free supernatants (CFSs) from these bacterial isolates were examined for antimicrobial activity against C. difficile growth by broth dilution method. 10 x concentrated CFSs of five isolates showed inhibition for C. difficile growth which was significantly different (p < 0.001) from control. Lactobacillus agilis T99A and Clostridium butyricum T58A isolates were selected for further evaluation of the produced antimicrobials. The antimicrobial activity of 10x CFSs of the two isolates was stable after enzymatic treatment with proteinase K or heating treatments up to 90 °C or neutralizing pH. The spectrum of activity of the two isolates was evaluated using different gram-positive and gram-negative bacterial species and did not show antimicrobial activity against these species. Our results showed two unconventional bacterial isolates: L. agilis T99A and C. butyricum T58A producing extracellular thermo stable antimicrobial agents against C. difficile clinical isolates.

Probiotics mitigating subclinical necrotic enteritis (SNE) as potential alternatives to antibiotics in poultry

Subclinical necrotic enteritis (SNE) caused by Clostridium perfringens (CP), is an important disease in chickens, which causes huge economic losses by damaging the intestinal mucosa, decreasing digestion and absorption of nutrients. Use of antibiotics at a sub-therapeutic level as antimicrobial growth promoters in poultry feed prevents the birds from SNE and improves growth. Due to the ban on the use of antibiotics in 2006 as antimicrobial growth promoters have led to the reemergence of the disease. Worldwide numerous studies have been carried out to investigate the alternatives to antibiotics for the prevention of SNE. Possible alternatives to control SNE include probiotics, prebiotics, bacteriophages, essential oils, organic acids, secondary metabolites and other microbial products. Currently, probiotics are most extensively used in poultry production as an alternative to antibiotics. This review summarizes recent insights and experimental evidence on the use of different microorganisms like Bacillus, Lactic acid bacteria, Bifidobacteria, Enterococcus, yeast, etc. as valuable probiotics for prevention of SNE and potential molecular mechanisms responsible for ameliorating effects of probiotics against SNE.

Effect of Bacillus subtilis DSM 32315 on the intestinal structural integrity and growth performance of broiler chickens under necrotic enteritis challenge

The effect of dietary inclusion of Bacillus subtilis DSM 32315 on the intestinal health and growth performance of Cobb 500 male broilers subjected to a Clostridium perfringens-induced necrotic enteritis (NE) challenge was determined in 2 experiments. In experiment 1, chicks were randomly assigned to 4 treatments of 10 replicate/treatment. In experiment 2, chicks were randomly assigned to 4 treatments of 12 replicates/treatment. The experimental treatments were non-infected, non-supplemented control, infected, non-supplemented control (IC), infected + Bacillus subtilis DSM 32315 (B. subtilis DSM 32315), infected + bacitracin methylene disalicylate (BMD). In both experiments, NE was induced by oral inoculation of toxin producing C. perfringens on 3 consecutive days between 17 and 20 D of age, following exposure of birds to pre-disposing conditions. At day 28 (experiment 1), broilers fed diets with B. subtilis DSM 32315 exhibited a significantly higher body weight, lower mortality, and intestinal NE lesion score, compared to the IC treatment. At day 42 (experiment 2), B. subtilis DSM 32315 supplementation significantly improved BW, feed conversion ratio, production efficiency factor, NE lesion score, and mortality, compared to IC treatment. The effect of B. subtilis DSM 32315 on intestinal integrity of NE challenged chickens was evaluated with histomorphometry. A significantly shallower crypt depth and higher villus height to crypt depth ratio were observed in the mid-intestine of birds belonging to the B. subtilis DSM 32315 group, compared to the IC group. Furthermore, B. subtilis DSM 32315 supplementation significantly reduced the enteritis index associated with NE. In both experiments, the effect of B. subtilis DSM 32315 on the phenotypic measurements of NE and performance was comparable to the effect observed with BMD supplementation. In conclusion, supplementation of the direct fed microbial strain B. subtilis DSM 32315 can ameliorate the pathology and performance detriments associated with NE.

Production, nitrogenous compounds in manure and serum chemistry of laying hens provided multi-species (Lactobacillus spp.) probiotics

Context A practical, low-cost suggestion for industry to reduce ammonia (NH3) in layer houses is use of Lactobacillus species (L. rhamnosus, L. paracasei and L. plantarum) in drinking water or feed. Thus, we investigated their short-term (8 weeks) use in young layers. Aim A combination of species of Lactobacillus (L. rhamnosus, L. paracasei and L. plantarum at 1.0 × 1012 CFU/kg feed) was provided for laying hens in order to investigate effects on production, nitrogenous compounds in manure, serum chemistry and uric acid in the liver. Method Ninety-six White Leghorns (32 weeks old) were randomly assigned to a control diet (commercial feed) or a diet containing commercial feed + probiotics (g/kg feed: L. rhamnosus 1.667, L. paracasei 0.667 and L. plantarum 0.740) and fed for an additional 8 weeks. Key results No significant major effects were observed among diets on bodyweight, feed intake, egg production or feed conversion ratio. Numerical reductions were noted for feed intake (10%) and feed conversion ratio (9%) at Week 2 for layers receiving probiotics as compared to the control. Ammonia, ammonium-nitrogen (N), total Kjeldahl N and total N in manure were not changed significantly by probiotics, nor did probiotics significantly affect the serum profile (ammonia, uric acid, total protein, albumin and creatine kinase) or uric acid in the liver. There was a numerical but non-significant increase in creatine kinase (11%) after 8 weeks in serum of hens receiving probiotics; likewise, there was a non-significant 8% increase in uric acid concentration in the liver of hens receiving probiotics at the end of the experimental period. Conclusion The probiotics (L. rhamnosus, L. paracasei and L. plantarum at 1.0 × 1012 CFU/kg feed) used in this study did not significantly reduce N-containing compounds in manure of 32–40-week-old layers. Implications Age, different types of layers (and broilers) and mode of administration or concentration of probiotics play important roles in outcomes. Extensive collaborative studies are needed to provide definitive answers for use of probiotics in layer (as well as broiler) feed for reduction of N-containing compounds in poultry houses.

The Effect of Clostridium butyricum on Gut Microbiota, Immune Response and Intestinal Barrier Function During the Development of Necrotic Enteritis in Chickens

Necrotic enteritis (NE) causes huge economic losses to the poultry industry. Probiotics are used as potential alternatives to antibiotics to prevent NE. It is known that Clostridium butyricum can act as a probiotic that can prevent infection. However, whether or not it exerts a beneficial effect on NE in chickens remains elusive. Therefore, we investigated the impact of C. butyricum on immune response and intestinal microbiota during the development of NE in chickens, including experimental stages with basal diets, high-fishmeal-supplementation diets, and Clostridium perfringens challenge. Chickens were divided into two groups from day 1 to day 20: one group had its diet supplemented with C. butyricum supplementation and one did not. At day 20, the chickens were divided into four groups: C. perfringens challenged and unchallenged chickens with and without C. butyricum supplementation. All groups were fed a basal diet for 13 days and thereafter a basal diet with 50% fishmeal from day 14 to 24. Chickens were infected with C. perfringens from day 21 to 23. At days 13, 20 and 24, samples were collected for analysis of the relative expression of immune response and intestinal mucosa barrier-related genes and intestinal microbes. The results show that C. butyricum can inhibit the increase in IL-17A gene expression and the reduction in Claudin-1 gene induced-expression caused by C. perfringens challenge. Moreover, C. butyricum was found to increase the expression of anti-inflammatory IL-10 in infected chickens. Although C. butyricum was found to have a significant beneficial effect on the structure of intestinal bacteria in the basal diet groups and decrease the abundance of C. perfringens in the gut, it did not significantly affect the occurrence of intestinal lesions and did not significantly correct the shift in gut bacterial composition post C. perfringens infection. In conclusion, although C. butyricum promotes the expression of anti-inflammatory and tight junction protein genes and inhibits pro-inflammatory genes in C. perfringens-challenged chickens, it is not adequate to improve the structure of intestinal microbiota in NE chickens. Therefore, more effective schemes of C. butyricum supplementation to prevent and treat NE in chickens need to be identified.

Health promoting activities of probiotics

In recent years, probiotics have received increasing attention and become one type of popular functional food because of their many biological functions. Among these desirable biological functions, the immune regulation, antioxidative activities, and antimicrobial effects are essential properties to maintain host health. Probiotics can regulate the immune system and improve the antioxidative system by producing microbial components and metabolites. Meanwhile, probiotics also possess antimicrobial abilities owing to their competition for nutrient requirements and mucus adherence, reducing pathogenic toxins, producing antimicrobial metabolites (short-chain fatty acids, bacteriocins, reuterin, linoleic acid, and secondary bile acids) and enhancing intestinal, or systemic immunity. Therefore, probiotics could be used to alleviate heavy metal toxicity and metabolic disorders by improving immunity, the antioxidative system, and intestinal micro-environment. This comprehensive review mainly highlights the potential health promoting activities of probiotics based on their antioxidative, antimicrobial, and immune regulatory effects. PRACTICAL APPLICATIONS: The antioxidative defense and the immune system are essential to maintain human health. However, many factors may result in microbial dysbiosis in the gut, which subsequently leads to pathogenic expansion, oxidative stress, and inflammatory responses. Therefore, it is important to explore beneficial foods to prevent or suppress these abnormal responses. Successful application of probiotics in the functional foods has attracted increasing attention due to their immune regulatory, antioxidative, and antimicrobial properties. The aim of this review is to introduce immune regulatory antioxidative and antimicrobial effects of probiotics, which provides some basic theories for scientific research and development of potential functional foods.

The effects of probiotic Bacillus coagulans on the cytotoxicity and expression of alpha toxin gene of Clostridium perfringens type A

Around the world, Clostridium perfringens type A is known to be a common foodborne pathogen. Therefore, the control and treatment of food poisoning caused by this pathogen are important. This study investigated, in vitro, the effects of Bacillus coagulans and its culture extracts on alpha toxin gene expression, growth inhibition, cytotoxicity, and apoptosis induced by C. perfringens spore, germinated spore and its enterotoxin. Flow cytometry was used to evaluate the apoptosis rate, and MTT test was used to evaluate cytotoxicity. Minimum inhibitory concentration was also used to measure the percentage of inhibition in the broth medium. Finally, RT-qPCR was used to evaluate alpha toxin gene expression. The results showed that the B. coagulans culture extract was able to inhibit the growth of the germinated spore of C. perfringens. Moreover, treating the extract with pepsin can reduce growth in the broth medium. MTT and flow cytometry showed that both B. coagulans and its extract can significantly reduce the cytotoxicity and apoptosis rate induced by C. perfringens type A. In addition, it was shown that the co-culture of B. coagulans and C. perfringens decreases alpha toxin gene expression. The findings of this study indicate that B. coagulans, with growth inhibition and reduced expression of alpha toxin in C. perfringens, can reduce the cytotoxicity and apoptosis rate induced on HT-29 cells.

Inhibition of Clostridium difficile in Mice Using a Mixture of Potential Probiotic Strains Enterococcus faecalis NM815, E. faecalis NM915, and E. faecium NM1015: Novel Candidates to Control C. difficile Infection (CDI)

This study is aimed at the isolation, identification, and characterization of potential probiotic strains capable of inhibiting Clostridium difficile in vitro and in vivo. Twenty isolates were isolated from infant fecal samples and screened against C. difficile using their cell-free supernatant. Only three isolates showed maximum inhibition from 56.05 to 60.60%, thus they were characterized for probiotic properties and safety. The results obtained approved their tolerance to the gastrointestinal tract conditions and safety profile. They were identified by sequencing 16S rRNA as Enterococcus faecalis NM815, E. faecalis NM915, and Enterococcus faecium NM1015. For in vivo evaluation, a viable mixture of these three strains (10⁹ CFU/mL) was administrated to a group of mice (treated group) in daily dose for 14 days, then followed by challenge with viable C. difficile (10⁵ CFU/mL) in daily dose for 7 days, then a second administration of a viable mixture of the three strains was done daily for 7 days. In addition, the control group was administered PBS buffer only and the untreated group received PBS buffer instead of the probiotic mixture before and after the challenge with C. difficile. The results obtained from histological analysis confirmed the effectiveness of our three potential probiotic strains which expressed inhibition of C. difficile and maintained the structural integrity of the liver and intestinal cells.

Enlisting commensal microbes to resist antibiotic-resistant pathogens

The emergence of antibiotic-resistant bacterial pathogens is an all-too-common consequence of antibiotic use. Although antibiotic resistance among virulent bacterial pathogens is a growing concern, the highest levels of antibiotic resistance occur among less pathogenic but more common bacteria that are prevalent in healthcare settings. Patient-to-patient transmission of these antibiotic-resistant bacteria is a perpetual concern in hospitals. Many of these resistant microbes, such as vancomycin-resistant Enterococcus faecium and carbapenem-resistant Klebsiella pneumoniae, emerge from the intestinal lumen and invade the bloodstream of vulnerable patients, causing disseminated infection. These infections are associated with preceding antibiotic administration, which changes the intestinal microbiota and compromises resistance to colonization by antibiotic-resistant bacteria. Recent and ongoing studies are increasingly defining commensal bacterial species and the inhibitory mechanisms they use to prevent infection. The use of next-generation probiotics derived from the intestinal microbiota represents an alternative approach to prevention of infection by enriching colonization with protective commensal species, thereby reducing the density of antibiotic-resistant bacteria and also reducing patient-to-patient transmission of infection in healthcare settings.