Enterococci as probiotics and their implications in food safety

Phenotypic and genotypic characterization of antimicrobial resistances reveals the effect of the production chain in reducing resistant lactic acid bacteria in an artisanal raw ewe milk PDO cheese

Antimicrobial resistance (AMR) is a significant public health threat, with the food production chain, and, specifically, fermented products, as a potential vehicle for dissemination. However, information about dairy products, especially raw ewe milk cheeses, is limited. The present study analysed, for the first time, the occurrence of AMRs related to lactic acid bacteria (LAB) along a raw ewe milk cheese production chain for the most common antimicrobial agents used on farms (dihydrostreptomycin, benzylpenicillin, amoxicillin and polymyxin B). More than 200 LAB isolates were obtained and identified by Sanger sequencing (V1-V3 16S rRNA regions); these isolates included 8 LAB genera and 21 species. Significant differences in LAB composition were observed throughout the production chain (P ≤ 0.001), with Enterococcus (e.g., E. hirae and E. faecalis) and Bacillus (e.g., B. thuringiensis and B. cereus) predominating in ovine faeces and raw ewe milk, respectively, along with Lactococcus (L. lactis) in whey and fresh cheeses, while Lactobacillus and Lacticaseibacillus species (e.g., Lactobacillus sp. and L. paracasei) prevailed in ripened cheeses. Phenotypically, by broth microdilution, Lactococcus, Enterococcus and Bacillus species presented the greatest resistance rates (on average, 78.2 %, 56.8 % and 53.4 %, respectively), specifically against polymyxin B, and were more susceptible to dihydrostreptomycin. Conversely, Lacticaseibacillus and Lactobacillus were more susceptible to all antimicrobials tested (31.4 % and 39.1 %, respectively). Thus, resistance patterns and multidrug resistance were reduced along the production chain (P ≤ 0.05). Genotypically, through HT-qPCR, 31 antimicrobial resistance genes (ARGs) and 6 mobile genetic elements (MGEs) were detected, predominating Str, StrB and aadA-01, related to aminoglycoside resistance, and the transposons tnpA-02 and tnpA-01. In general, a significant reduction in ARGs and MGEs abundances was also observed throughout the production chain (P ≤ 0.001). The current findings indicate that LAB dynamics throughout the raw ewe milk cheese production chain facilitated a reduction in AMRs, which has not been reported to date.

Short-term supplementation with uncoated and encapsulated Enterococcus faecium affected growth performance, gut microbiome and intestinal barrier integrity in broiler chickens

Enterococcus faecium (E. faecium) is an alternative to antibiotics, while the probiotic effect of short-term application in mature broiler chickens remains unclear. In the current study, 48 Arbor Acres male broilers were chosen to investigate the effects of E. faecium on growth performance, the gut microbiome and intestinal health during the finishing period. Forty-eight birds were randomly allocated to 4 treatment groups that were fed a corn-soybean meal basal diet (Con), a basal diet supplemented with 1 g/kg amoxicillin (ABX), 5×106 CFU/g encapsulated E. faecium (cEF), or 5×106 CFU/g uncoated E. faecium (EF) from d 33 to 42. The results showed that 10 d of antibiotic treatment decreased the growth performance of the broilers (P < 0.05). The feed conversion ratio of the cEF and EF groups were lower than that of the Con group by 0.13 and 0.07, respectively (P > 0.05). The abundance of viable ileal and cecal E. faecium in the cEF group was greater than that in the EF group (P < 0.05), and both groups were markedly greater than those in the Con and ABX groups (P < 0.05). The ABX treatment decreased the Shannon and Chao1 indices of the cecal microbiota, while the dietary E. faecium treatment resulted in significant differences in the β diversity of the ileal and cecal microbiota (P < 0.05). Mantel correlation revealed that the ileal microbiota at the genus level was significantly correlated with the growth performance of broilers, with Lactobacillus, Bacillus and Escherichia-Shigella showing positive and strong correlations (P < 0.05). In the ileum, the crypt depth was lower in the cEF group than in the Con group, but the villi height-to-crypt depth ratio was greater in the cEF group than in the other groups (P = 0.037). However, the expression of the ZO-2 and Occludin genes was downregulated in the E. faecium-fed birds (P < 0.05). In the cecum, the acetate, butyrate and total SCFA levels were greater in the EF group (P < 0.05), while the propionate, isobutyrate and isovalerate levels were lower in the ABX group (P < 0.05). In summary, 10 d of dietary supplementation with E. faecium markedly increased colonization in mature broilers and potentially improved growth performance by modulating the ileal microbiota. Encapsulation techniques could enable a slow release of E. faecium in the intestine, thereby reducing the negative impacts of rapid expansion of E. faecium on the intestinal epithelium.

Probiotic potential of Streptomyces levis strain HFM-2 isolated from human gut and its antibiofilm properties against pathogenic bacteria

BACKGROUND

Antimicrobial resistance (AMR) is a serious worldwide public health concern that needs immediate action. Probiotics could be a promising alternative for fighting antibiotic resistance, displaying beneficial effects to the host by combating diseases, improving growth, and stimulating the host immune responses against infection. This study was conducted to evaluate the probiotic, antibacterial, and antibiofilm potential of Streptomyces levis strain HFM-2 isolated from the healthy human gut.

RESULTS

In vitro antibacterial activity in the cell-free supernatant of S. levis strain HFM-2 was evaluated against different pathogens viz. K. pneumoniae sub sp. pneumoniae, S. aureus, B. subtilis, VRE, S. typhi, S. epidermidis, MRSA, V. cholerae, M. smegmatis, E. coli, P. aeruginosa and E. aerogenes. Further, the ethyl acetate extract from S. levis strain HFM-2 showed strong biofilm inhibition against S. typhi, K. pneumoniae sub sp. pneumoniae, P. aeruginosa and E. coli. Fluorescence microscopy was used to detect biofilm inhibition properties. MIC and MBC values of EtOAc extract were determined at 500 and 1000 µg/mL, respectively. Further, strain HFM-2 showed high tolerance in gastric juice, pancreatin, bile, and at low pH. It exhibited efficient adhesion properties, displaying auto-aggregation (97.0%), hydrophobicity (95.71%, 88.96%, and 81.15% for ethyl acetate, chloroform and xylene, respectively), and showed 89.75%, 86.53%, 83.06% and 76.13% co-aggregation with S. typhi, MRSA, S. pyogenes and E. coli, respectively after 60 min of incubation. The S. levis strain HFM-2 was susceptible to different antibiotics such as tetracycline, streptomycin, kanamycin, ciprofloxacin, erythromycin, linezolid, meropenem, amikacin, gentamycin, clindamycin, moxifloxacin and vancomycin, but resistant to ampicillin and penicillin G.

CONCLUSION

The study shows that S. levis strain HFM-2 has significant probiotic properties such as good viability in bile, gastric juice, pancreatin environment, and at low pH; proficient adhesion properties, and antibiotic susceptibility. Further, the EtOAc extract of Streptomyces levis strain HFM-2 has a potent antibiofilm and antibacterial activity against antibacterial-resistant clinical pathogens.

Comparative genomic and metabolomic analysis reveals the potential of a newly isolated Enterococcus faecium B6 involved in lipogenic effects

Evidence has indicated that Enterococcus plays a vital role in non-alcoholic fatty liver disease (NAFLD) development. However, the microbial genetic basis and metabolic potential in the disease are yet unknown. We previously isolated a bacteria Enterococcus faecium B6 (E. faecium B6) from children with NAFLD for the first time. Here, we aim to systematically investigate the potential of strain B6 in lipogenic effects. The lipogenic effects of strain B6 were explored in vitro and in vivo. The genomic and functional characterizations were investigated by whole-genome sequencing and comparative genomic analysis. Moreover, the metabolite profiles were unraveled by an untargeted metabolomic analysis. We demonstrated that strain B6 could effectively induce lipogenic effects in the liver of mice. Strain B6 contained a circular chromosome and two circular plasmids and posed various functions. Compared to the other two probiotic strains of E. faecium, strain B6 exhibited unique functions in pathways of ABC transporters, phosphotransferase system, and amino sugar and nucleotide sugar metabolism. Moreover, strain B6 produced several metabolites, mainly enriched in the protein digestion and absorption pathway. The unique potential of strain B6 in lipogenic effects was probably associated with glycolysis, fatty acid synthesis, and glutamine and choline transport. This study pioneeringly revealed the metabolic characteristics and specific detrimental traits of strain B6. The findings provided new insights into the underlying mechanisms of E. faecium in lipogenic effects, and laid essential foundations for further understanding of E. faecium-related disease.

Lactiplantibacillus sp. D10-2: potential bacteria for eliminating bisphenol A and reducing BpA-induced lipid accumulation

Bisphenol A (BpA) is an endocrine-disrupting substance commonly found in plastics and resins. It is reported that BpA exposure induces lipid accumulation in humans, similar to obesogenic compounds. The main objective of this study is to investigate the removal of BpA using Lactiplantibacillus sp. D10-2, and to examine its potential for reducing BpA-induced lipid accumulation in 3T3-L1 cell line model. The heat-dried cells of Lactiplantibacillus sp. D10-2 showed 69.7% removal efficiency for initial BpA concentration of 10 μg/mL, which was 30.5% higher than the live cells. The absence of metabolites or intermediates in BpA removal studies indicates that the Lactiplantibacillus sp. D10-2 strain removed BpA by adsorption process. The hydrophobic interactions of heat-dried Lactiplantibacillus sp. D10-2 cells were observed to be higher with 33.7% compared to live cells (15.0%), suggesting a stronger ability to bind with BpA. Although the BpA binding onto Lactiplantibacillus sp. D10-2 was not affected by pH, it was confirmed that as the temperature increases, the binding ability got decreased due to mass transfer and diffusion of BpA molecules. Treatment with Lactiplantibacillus sp. D10-2 (0.1, 0.25, 0.5, 1%) reduced lipid accumulation by 61.7, 58.0, 52.7 and 60.4% in 3T3-L1 cells exposed with BpA. In addition, it was confirmed that Lactiplantibacillus sp. D10-2 treatment suppressed the protein expression levels of lipogenesis-related PPARγ and C/EBPα in 3T3-L1 cells. The results of the study suggest that the Lactiplantibacillus sp. D10-2 strain can remove BpA and reduce BpA-accelerated lipid accumulation in 3T3-L1 cells.

Prevalence and Molecular Characteristics of Enterococci Isolated from Clinical Bovine Mastitis Cases in Ningxia

Purpose

This study aimed to investigate the prevalence and genetic characterization of enterococcal isolates (Enterococcus faecalis, Enterococcus faecium and Enterococcus hirae) isolated from clinical bovine mastitis cases in Ningxia, China.

Patients and Methods

The enterococci were identified by 16S rRNA amplification and sequencing. Antimicrobial resistance was determined by disc diffusion method. Virulence and antimicrobial resistance genes were detected by PCR assays.

Results

Overall, 198 enterococcal isolates were identified from 2897 mastitis samples, including 137 (4.7%) E. faecalis, 50 (1.7%) E. faecium and 11 (0.4%) E. hirae. E. faecalis, E. faecium and E. hirae isolates showed high resistance to tetracycline (92.7%, 68.0%, 90.9%), followed by erythromycin (86.9%, 76.0%, 72.7%). The multidrug-resistant strains of E. faecalis and E. faecium were 29 (21.2%) and 13 (26.0%), respectively. The resistance of E. faecalis, E. faecium and E. hirae isolates to tetracycline is mainly attributed to the presence of tetL (alone or combined with tetM and/or tetK), the erythromycin resistance to ermB (alone or combined with ermC and/or ermA). Moreover, cpd (94.2%), gelE (77.4%), efaAfs (93.4%), and esp (79.6%) were the most common virulence genes in E. faecalis. In E. faecium, except for the gene efaAfs (82.0%), other virulence genes are rarely found. Only two strains of E. hirae carrying asa1 gene were detected.

Conclusion

The results of this study can provide a reference for the prevention and treatment of bovine mastitis caused by enterococci.

Genomic Insights Into Enterococcus mundtii 203: A Promising Probiotic Candidate Isolated From Camel Feces

Enterococcus, a common commensal organism in the human gut, exhibits a dual nature with certain strains offering probiotic benefits, while others are associated with nosocomial infections. In this study, we conducted a comprehensive examination of the genome of Enterococcus mundtii strain 203 to assess its probiotic potential and safety profile. The complete genome sequencing, assembly, and annotation were performed, followed by bioinformatics analysis. Our investigation reveals a detailed characterization of the Enterococcus mundtii 203 genome, originally isolated from camel feces, with a size of 3,053,234 bases and a GC content of 38.4%. Importantly, our analysis suggests that this strain poses no risk as a human pathogen due to the absence of antibiotic resistance determinants and virulence factors. The genome harbors a multitude of genes responsible for lactic acid production, bioactive peptide synthesis, adhesion molecule expression, resistance to harsh gut conditions, and enhancement of host metabolism. These findings underline the potential probiotic functionality of Enterococcus mundtii 203, positioning it as a promising candidate. Notably, our study did not identify any sequences related to insertion elements or CRISPR-Cas fragments.

The composition and function of bacterial communities in Bombyx mori (Lepidoptera: Bombycidae) changed dramatically with infected fungi: A new potential to culture Cordyceps cicadae

Cordyceps cicadae (Hypocreales: Cordycipitaceae) is a renowned entomopathogenic fungus used as herbal medicine in China. However, wild C. cicadae resources have been threatened by heavy harvesting. We hypothesised that Bombyx mori L. (Lepidoptera: Bombycidae) could be a new alternative to cultivate C. cicadae due to the low cost of rearing. Bacterial communities are crucial for the formation of Cordyceps and for promoting the production of metabolites. To better understand the bacterial community structure associated with Cordyceps, three Claviciptaceae fungi were used to explore the pathogenicity of the silkworms. Here, fifth-instar silkworms were infected with C. cicadae, Cordyceps cateniannulata (Hypocreales: Cordycipitaceae) and Beauveria bassiana (Hypocreales: Cordycipitaceae). Subsequently, we applied high-throughput sequencing to explore the composition of bacterial communities in silkworms. Our results showed that all three fungi were highly pathogenic to silkworms, which suggests that silkworms have the potential to cultivate Cordyceps. After fungal infection, the diversity of bacterial communities in silkworms decreased significantly, and the abundance of Staphylococcus increased in mummified larvae, which may play a role in the death process when the host suffers infection by entomopathogenic fungi. Furthermore, there were high similarities in the bacterial community composition and function in the C. cicadae and C. cateniannulata infected samples, and the phylogenetic analysis suggested that these similarities may be related to the fungal phylogenetic relationship. Our findings reveal that infection with different entomopathogenic fungi affects the composition and function of bacterial communities in silkworms and that the bacterial species associated with Cordyceps are primarily host dependent, while fungal infection affects bacterial abundance.

Molecular Assessments of Antimicrobial Protein Enterocins and Quorum Sensing Genes and Their Role in Virulence of the Genus Enterococcus

Enterococcus has emerged as an opportunistic pathogen because of its antibiotic resistance and virulence profile, which makes it a causative agent of several diseases like endocarditis, surgical site, and urinary tract infections. Currently, species of this genus are the 2nd most frequently isolated microorganisms from hospital-acquired infections. Significant association with hospitals and unhygienic conditions of the environments has made them resistant to a wide range of antibiotics. On the brighter side, enterococci have the ability to produce antimicrobial proteins (i.e., enterocins) that exhibit wide antagonistic activity, thus making them useful microbes in the food and pharmaceutical industries. Enterocins are also involved in niche control in gut microbiota which is regulated by the quorum sensing (QS) system. A bacterial communication system that is controlled by the fsr operon in enterococci consists of FsrABDC, ef1097, and GelE/SprE genes. Hence, the present study was conducted for molecular assessment of enterocins and quorum sensing genes, inter-environmental correlation, and species prevalence of enterococci isolated from different environmental niches of Karachi, Pakistan. Obtained results revealed the highest prevalence of E. faecium and E. faecalis in all environments. Bacterial antagonism and enterocin genes were observed significantly high in poultry environments. The inter-environmental correlation indicated a strong positive correlation of freshwater with sewage and soil environments. Similarly, the fsr regulatory system was mostly identified in poultry-related environments, and a significant correlation between QS system and biofilm formation was established. In conclusion, this study confirmed the high prevalence of E. faecium in all tested sources, high enterocin production in non-clinical environments, and more fsr regulatory genes in poultry-related environments.

Enterococcus faecalis: implications for host health

The microbiota represents a crucial area of research in maintaining human health due to its potential for uncovering novel biomarkers, therapies, and molecular mechanisms relevant to population identification and experimental model characterization. Among these microorganisms, Enterococcus faecalis, a Gram-positive bacterium found in the gastrointestinal tract of humans and animals, holds particular significance. Strains of this bacterial species have sparked considerable debate in the literature due to their dual nature; they can either be utilized as probiotics in the food industry or demonstrate resistance to antibiotics, potentially leading to severe illness, disability, and death. Given the diverse characteristics of Enterococcus faecalis strains, this review aims to provide a comprehensive understanding of their impact on various systems within the host, including the immunological, cardiovascular, metabolic, and nervous systems. Furthermore, we summarize the bacterium-host interaction characteristics and molecular effects to highlight their targets, features, and overall impact on microbial communities and host health.

Promiscuous, persistent and problematic: insights into current enterococcal genomics to guide therapeutic strategy

Vancomycin-resistant enterococci (VRE) are major opportunistic pathogens and the causative agents of serious diseases, such as urinary tract infections and endocarditis. VRE strains mainly include species of Enterococcus faecium and E. faecalis which can colonise the gastrointestinal tract (GIT) of patients and, following growth and persistence in the gut, can transfer to blood resulting in systemic dissemination in the body. Advancements in genomics have revealed that hospital-associated VRE strains are characterised by increased numbers of mobile genetic elements, higher numbers of antibiotic resistance genes and often lack active CRISPR-Cas systems. Additionally, comparative genomics have increased our understanding of dissemination routes among patients and healthcare workers. Since the efficiency of currently available antibiotics is rapidly declining, new measures to control infection and dissemination of these persistent pathogens are urgently needed. These approaches include combinatory administration of antibiotics, strengthening colonisation resistance of the gut microbiota to reduce VRE proliferation through commensals or probiotic bacteria, or switching to non-antibiotic bacterial killers, such as bacteriophages or bacteriocins. In this review, we discuss the current knowledge of the genomics of VRE isolates and state-of-the-art therapeutic advances against VRE infections.

In Vitro Profiling of Potential Fish Probiotics, Enterococcus hirae Strains, Isolated from Jade Perch, and Safety Properties Assessed Using Whole Genome Sequencing

The demands of intensified aquaculture production and escalating disease prevalence underscore the need for efficacious probiotic strategies to enhance fish health. This study focused on isolating and characterising potential probiotics from the gut microbiota of the emerging aquaculture species jade perch (Scortum barcoo). Eighty-seven lactic acid bacteria and 149 other bacteria were isolated from the digestive tract of five adult jade perch. The screening revealed that 24 Enterococcus hirae isolates inhibited the freshwater pathogens Aeromonas sobria and Streptococcus iniae. Co-incubating E. hirae with the host gut suspensions demonstrated a two- to five-fold increase in the size of growth inhibition zones compared to the results when using gut suspensions from tilapia (a non-host), indicating host-specificity. Genome analysis of the lead isolate, E. hirae R44, predicted the presence of antimicrobial compounds like enterolysin A, class II lanthipeptide, and terpenes, which underlay its antibacterial attributes. Isolate R44 exhibited desirable probiotic characteristics, including survival at pH values within the range of 3 to 12, bile tolerance, antioxidant activity, ampicillin sensitivity, and absence of transferable antimicrobial resistance genes and virulence factors commonly associated with hospital Enterococcus strains (IS16, hylEfm, and esp). This study offers a foundation for sourcing host-adapted probiotics from underexplored aquaculture species. Characterisation of novel probiotics like E. hirae R44 can expedite the development of disease mitigation strategies to support aquaculture intensification.

Evaluation of probiotic properties of a Brevibacillus laterosporus strain

Brevibacillus laterosporus is a strain of probiotic bacteria that has been widely used in pest control, cash crop, and other production areas. However, few studies have been conducted on its use as a feed additive in animals. Therefore, the probiotic potential of B. laterosporus PBC01 was evaluated by characterizing hydrophobicity, auto-aggregation activity, bile salt and simulated gastrointestinal fluid tolerance, bienzymatic, and antibacterial activity. Antibiotic susceptibility, hemolysis assays, and supplemental feeding of mice were also performed to evaluate safety features. Our results showed that B. laterosporus PBC01 had moderate hydrophobicity, high auto-agglutination ability. Meanwhile, B. laterosporus PBC01 had good tolerance to bile salt and simulated gastrointestinal fluid. It had the ability to secrete protease, cellulase, and to inhibit various pathogens. In addition, B. laterosporus PBC01 was sensitive to many antibiotics, and did not produce hemolysin. In the safety assessment of mice, it did not cause any deaths, nor did it affect the cell components of blood, antioxidant capacity, and reproductive health. The study indicated the great probiotic characteristics and safety of B. laterosporus PBC01. This may provide a theoretical basis for the clinical application and development of probiotic-based feed additives.

Opening avenues for treatment of neurodegenerative disease using post-biotics: Breakthroughs and bottlenecks in clinical translation

Recent studies have indicated the significant involvement of the gut microbiome in both human physiology and pathology. Additionally, therapeutic interventions based on microbiome approaches have been employed to enhance overall health and address various diseases including aging and neurodegenerative disease (ND). Researchers have explored potential links between these areas, investigating the potential pathogenic or therapeutic effects of intestinal microbiota in diseases. This article provides a summary of established interactions between the gut microbiome and ND. Post-biotic is believed to mediate its neuroprotection by elevating the level of dopamine and reducing the level of α-synuclein in substantia nigra, protecting the loss of dopaminergic neurons, reducing the aggregation of NFT, reducing the deposition of amyloid β peptide plagues and ameliorating motor deficits. Moreover, mediates its neuroprotective activity by inhibiting the inflammatory response (decreasing the expression of TNFα, iNOS expression, free radical formation, overexpression of HIF-1α), apoptosis (i.e. active caspase-3, TNF-α, maintains the level of Bax/Bcl-2 ratio) and promoting BDNF secretion. It is also reported to have good antioxidant activity. This review offers an overview of the latest findings from both preclinical and clinical trials concerning the use of post-biotics in ND.

Functional antagonism and insights into the biosynthetic potential of human gut-derived microbes

The specialised small molecules encoded by commensal microbes mediate distinct functional interactions. However, there is a landscape of antagonistic interactions mediated by specialised strains and their small molecules. Herein, the antagonistic landscape within a collection of 330 human gut-derived commensal microbial strains was elucidated to evaluate antimicrobial interactions as a defensive contributor, and gain new insights into structure-related functions. The potential antagonistic gut-derived strains displayed strain-specific selective inhibition. This is in contrast to common antimicrobial drugs, which typically wipe out a broad range of species and are usually found in environmental microbes. Genome sequencing of representative gut strains revealed the presence of significant biosynthetic gene clusters (BGCs) encoding compound families that contribute to antagonistic activities, and are important in host defence and maintaining gut homeostasis. Subsets of these BGCs were abundant in metagenomic sequencing data from healthy individuals. Furthermore, the cell culture secretome of these strains revealed potential biomarkers linked to hallmark pathways. These microorganisms have biosynthetic novelty and are a source of biologically significant natural products. Such natural products are essential in the development of new antimicrobial agents to reduce the usage of broad-spectrum antibiotics and combat antimicrobial resistance.

An Integrated Comprehensive Peptidomics and In Silico Analysis of Bioactive Peptide-Rich Milk Fermented by Three Autochthonous Cocci Strains

Bioactive peptides (BPs) are molecules of paramount importance with great potential for the development of functional foods, nutraceuticals or therapeutics for the prevention or treatment of various diseases. A functional BP-rich dairy product was produced by lyophilisation of bovine milk fermented by the autochthonous strains Lactococcus lactis subsp. lactis ZGBP5-51, Enterococcus faecium ZGBP5-52 and Enterococcus faecalis ZGBP5-53 isolated from the same artisanal fresh cheese. The efficiency of the proteolytic system of the implemented strains in the production of BPs was confirmed by a combined high-throughput mass spectrometry (MS)-based peptidome profiling and an in silico approach. First, peptides released by microbial fermentation were identified via a non-targeted peptide analysis (NTA) comprising reversed-phase nano-liquid chromatography (RP nano-LC) coupled with matrix-assisted laser desorption/ionisation-time-of-flight/time-of-flight (MALDI-TOF/TOF) MS, and then quantified by targeted peptide analysis (TA) involving RP ultrahigh-performance LC (RP-UHPLC) coupled with triple-quadrupole MS (QQQ-MS). A combined database and literature search revealed that 10 of the 25 peptides identified in this work have bioactive properties described in the literature. Finally, by combining the output of MS-based peptidome profiling with in silico bioactivity prediction tools, three peptides (75QFLPYPYYAKPA86, 40VAPFPEVFGK49, 117ARHPHPHLSF126), whose bioactive properties have not been previously reported in the literature, were identified as potential BP candidates.

Enterocins Produced by Enterococci Isolated from Breast-Fed Infants: Antilisterial Potential

Enterocins are bacteriocins synthesized by Enterococcus strains that show an interesting antimicrobial effectiveness against foodborne pathogens such as Listeria monocytogenes. The objectives of this study were to identify and analyze the expression of enterocin genes of Enterococcus isolated from breast-fed infants and evaluate their ability to inhibit three human isolates of virulent L. monocytogenes, as well as some probiotic bacteria. The susceptibility of the strains of L. monocytogenes to fifteen antibiotics was tested, detecting their resistance to cefoxitin (constitutively resistant), oxacillin, and clindamycin. The production of enterocins A, B, and P was observed in Enterococcus faecium isolates, while enterocin AS-48 was detected in an Enterococcus faecalis isolate. AS-48 showed antilisterial activity by itself, while the joint action of enterocins A and B or B and P was necessary for inhibiting L. monocytogenes, demonstrating the synergistic effect of those combinations. The presence of multiple enterocin genes does not assure the inhibition of L. monocytogenes strains. However, the expression of multiple enterocin genes showed a good correlation with the inhibition capacity of these strains. Furthermore, the potential beneficial strains of lactobacilli and bifidobacteria examined were not inhibited by any of the enterocins produced individually or in combination, with the exception of Bifidobacterium longum BB536, which was inhibited by enterocin AS-48 and the joint production of enterocins A and B or B and P. The enterocins studied here could be candidates for developing alternative treatments against antibiotic-resistant bacterial infections. Moreover, these selected enterocin-producing E. faecium strains isolated from breast-fed infants could be used as probiotic strains due to their antilisterial effect, as well as the absence of virulence factors.

Genomic and phenotypic characterisation of Enterococcus mundtii AM_AQ_BC8 for its anti-biofilm, antimicrobial and probiotic potential

Enterococcus mundtii AM_AQ_BC8 isolated from biofouled filtration membrane was characterised as a potential probiotic bacterium showing strong L-lactic acid-producing capability. Experimental studies revealed that E. mundtii AM_AQ_BC8 possess antibiofilm and antimicrobial ability too, as tested against strong biofilm-forming bacteria like Pseudomonas spp. The present study has evaluated the genetic potential of E. mundtii AM_AQ_BC8 through genome sequencing. Whole genome analysis revealed the presence of key genes like ldh_1 and ldh_2 responsible for lactic acid production along with genes encoding probiotic features such as acid and bile salt resistance (dnaK, dnaJ, argS), fatty acid synthesis (fabD, fabE) and lactose utilisation (lacG, lacD). The phylogenomic analysis based on OrthoANI (99.85%) and dDDH (96.8%) values revealed that the strain AM_AQ_BC8 shared the highest homology with E. mundtii. The genome sequence of strain AM_AQ_BC8 has been deposited to NCBI and released with GenBank accession no. SAMN32531201. The study primarily demonstrated the probiotic potential of E. mundtii AM_AQ_BC8 isolate, for L-lactate synthesis in high concentration (8.98 g/L/day), which also showed anti-biofilm and antimicrobial activities.

Pathogenic Potential and Antibiotic Susceptibility: A Comprehensive Study of Enterococci from Different Ecological Settings

The pathway and the lifestyle of known enterococcus species are too complicated. The aim of the present study is to trace the path of pathogenicity of enterococci isolated from seven habitats (Cornu aspersum intestine; Bulgarian yoghurt; goat and cow feta cheese-mature and young, respectively; Arabian street food-doner kebab; cow milk; and human breast milk) by comparing their pathogenic potential. In total, 72 enterococcal strains were isolated and identified by MALDI-TOF, sequencing, and PCR. Hemolytic and gelatinase activity were biochemically determined. PCR was carried out for detection of virulence factors (cylB, esp, gls24, nucl, psaA, agg, gelE, and ace) and antibiotic resistance (erm, ermB, blaZ, vanA, aphA, mefA, gyrA, catpIP501, and aac6'-aph2″). Phenotypic antibiotic resistance was assigned according to EUCAST. Eleven representatives of the genus Enterococcus were identified: E. mundtii, E. casseliflavus, E. gilvus, E. pseudoavium, E. pallens, E. malodoratus, E. devriesei, E. gallinarum, E. durans, E. faecium, and E. faecalis. Twenty-two strains expressed α-hemolysis. Thirteen strains had the cylB gene. Only two strains expressed α-hemolysis and possessed the cylB gene simultaneously. Positive amplification for gelE was found in 35% of the isolates, but phenotypic gelatinase activity was observed only in three strains. All isolates showed varying antibiotic resistance. Only E. faecalis BM15 showed multiple resistance (AMP-HLSR-RP). Correlation between genotypic and phenotypic macrolide resistance was revealed for two E. faecalis strains.

Clinical Implications of Probiotics in Oral and Periodontal Health: A Comprehensive Review

Probiotic therapy represents a novel concept in dentistry. The microbial nature of dental plaque can be altered, or the probiotic strategy can efficiently inhibit oral pathogens. Probiotics are dietary supplements that are vital for boosting immunity as they include beneficial bacteria and yeast. In dentistry and medicine, the interest in probiotics, prebiotics, and synbiotics is increasing. By forming a biofilm and assisting in preventing dental cavities, probiotics play a crucial role in dentistry and significantly impact immunity. Prebiotics are non-digestible dietary supplements that enhance health by increasing the quantity and activity of beneficial bacteria such as Lactobacilli and Bifidobacteria. It has been demonstrated that prebiotics, in addition to probiotics, can help treat oral diseases. They promote the growth and activity of beneficial organisms while inhibiting potentially harmful bacteria's growth and activity. Synbiotics are dietary supplements that combine probiotics and prebiotics, believed to work in tandem through a process known as synergism. Studies have indicated that synbiotics, or a combination of probiotics with a prebiotic, may have greater efficacy than either supplement alone.

Effects of supplementing a direct-fed microbial containing Enterococcus faecium 669 on performance, health, and metabolic responses of preweaning Holstein dairy calves

This study aimed to evaluate the effects of Enterococcus faecium 669 supplementation on performance, health, parasitological, microbiological, and hematological responses of preweaning dairy calves. Forty-two newborn Holstein female calves (initial body weight [BW] 44 ± 4.5 kg) were used in the present study. At birth, calves were ranked by initial BW and assigned to 1 of 2 treatment groups: (1) whole milk (CON; n = 21) and (2) whole milk with the addition of direct-fed microbial Ent. faecium 669 (DFM; n = 21). During the entire experimental period (63 d), DFM was daily-fed at a rate of 2.5 × 109 cfu/head. All calves were offered a mixture of a starter feed and wheat straw for ad libitum consumption. Supplement intake was evaluated daily, whereas calves were weighed on a weekly basis from d 0 to weaning (d 63). Diarrhea was assessed once a day, and fecal and blood samples were collected for microbiological, parasitological, and hematological responses. All data were analyzed with SAS using calf as the experimental unit. A treatment × week interaction was observed for BW, as DFM-supplemented calves were heavier than CON cohorts on d 56 (+ 4.7 kg) and at weaning on d 63 (+ 4.8 kg). A similar interaction was observed for average daily gain (ADG) and dry matter intake (DMI), with greater ADG for DFM-supplemented calves from d 35 to 42, greater ADG and DMI from d 49 to 56, and greater DMI from d 56 to weaning. Moreover, diarrhea occurrence tended to be lower, whereas rectal temperature was 0.2°C lower for DFM-supplemented calves. Treatment × day interactions were observed for the occurrence and counts of Eimeria spp., as DFM-supplemented calves tended to have a reduced number of positive observations on d 42 of the study versus CON, and a significant reduction in positive animals from d 21 to 42 was observed in the DFM group but not in CON calves. For Cryptosporidium spp., no treatment effects were observed on overall occurrence (%), but DFM-supplemented calves had a greater count of oocyst per gram versus CON. No treatment × day interaction or main treatment effects were observed for any of the blood variables analyzed herein, exception being monocytes concentration. In summary, preweaning Ent. faecium 669 supplementation improved performance, diarrhea occurrence, and reduced the number of calves positively-detected for Eimeria spp.

Potential application of phage vB_EfKS5 to control Enterococcus faecalis and its biofilm in food

Contaminated food with antibiotic-resistant Enterococcus spp. could be the vehicle for transmitting Enterococcus to humans and accordingly cause a public health problem. The accumulation of biogenic amines produced by Enterococcus faecalis (E. faecalis) in food may have cytological effects. Bacteriophages (phage in short) are natural antimicrobial agents and can be used alone or in combination with other food preservatives to reduce food microbial contaminants. The aim of this study was to isolate a novel phage against E. faecalis and determine its host range to evaluate its potential application. Bacteriophage, vB_EfKS5, with a broad host range, was isolated to control the growth of E. faecalis. The vB_EfKS5 genome is 59,246 bp in length and has a GC content of 39.7%. The computational analysis of phage vB_EfKS5 genome confirmed that it does not contain any lysogenic, toxic, or virulent genes. Phage vB_EfKS5 exhibited lytic activity against most E. faecalis isolates with different multiplicities of infections and it infected 75.5% (22/29) of E. faecalis isolates and 42.3% (3/7) of E. faecium isolates. It was also able to destroy the biofilm formed by E. faecalis with different MOIs. Phage vB_EfKS5 alone or in combination with nisin could control the growth of E. faecalis in broth and milk. Based on its high productivity, stability, short latent period, and large burst size, phage vB_EfKS5 has a high potential for applications both in food and medical applications.

Intestinal microbiota modulation at the strain level by the olive oil polyphenols in the diet

Introduction

Previously we have reported a r16S gene next generation sequencing study on the effect of high fat diets in the intestinal microbiota using a murine model. However, many important microbial traits occur at strain level and, in order to detect these population changes, culture-dependent approaches need to be applied. With this goal, we decided to study a very well-known commensal genus, Enterococcus, and therefore, intestinal enterococci methodically isolated during the above-mentioned experiment were analyzed.

Materials and methods

A collection of 75 distinct enterococcal strains isolated from feces of mice fed a standard diet or high-fat diets enriched with butter, refined olive oil, or extra virgin olive oil and after 0, 6 or 12 weeks of diet, were genetically and phenotypically characterized in search of virulence factors, biogenic amine production and antibiotic resistance. All strains were tested for the susceptibility in vitro to two virgin olive oil polyphenols, oleuropein (the bitter principle of olives) and hydroxytyrosol (derived from oleuropein by enzymatic hydrolysis and responsible for the high stability of olive oil).

Results

No drastic polyphenol effect was found except at high concentrations. However, when carrying out a comparative statistical study in the 75 strains of the collection according to the different diets, we have detected significant differences between the strains isolated from mice fed with a diet enriched with virgin olive oil and the rest of the diets. EVOO strains also presented less resistance to antibiotics and a more beneficial profile overall.

Discussion

These results support the prebiotic role of polyphenols, showing how they are able to modulate the set of strains that comprises a genus in the gut, allowing them to adapt to a changing environment in the host's intestine and possibly exerting effects on its physiology.

Probiotic potentials of lactic acid bacteria isolated from Egyptian fermented food

Lactic acid bacteria (LAB) are of major concern due to their health benefits. Fermented food products comprise variable LAB demonstrating probiotic properties. Discovering and evaluating new probiotics in fermented food products poses a global economic and health importance. Therefore, the present work aimed to investigate and evaluate the probiotic potentials of LAB strains isolated from Egyptian fermented food. In this study, we isolated and functionally characterized 100 bacterial strains isolated from different Egyptian fermented food sources as probiotics. Only four LAB strains amongst the isolated LAB showed probiotic attributes and are considered to be safe for their implementation as feed or dietary supplements. Additionally, they were shown to exert antimicrobial activities against pathogenic bacteria and anticancer effects against the colon cancer cell line Caco-2. The Enterococcus massiliensis IS06 strain was exclusively reported in this study as a probiotic strain with high antimicrobial, antioxidant, and anti-colon cancer activity. Hitherto, few studies have focused on elucidating the impact of probiotic supplementation in vivo. Therefore, in the current study, the safety of the four strains was tested in vivo through the supplementation of rats with potential probiotic strains for 21 days. The results revealed that probiotic bacterial supplementation in rats did not adversely affect the general health of rats. The Lactiplantibacillus plantarum IS07 strain significantly increased the growth performance of rats. Furthermore, the four strains exhibited increased levels of antioxidants such as superoxide dismutase and glutathione in vivo. Consistently, all strains also showed high antioxidant activity of the superoxide dismutase enzyme in vitro. Overall, these findings demonstrated that these isolated potential probiotics harbor desirable characteristics and can be applied widely as feed additives for animals or as dietary supplements for humans to exert their health benefits and combat serious diseases.

Molecular Assessment and Validation of the Selected Enterococcal Strains as Probiotics

Probiotics are live microorganisms which confer health benefits to the host. Lactic acid bacteria (LAB) are used as probiotics since decades. Enterococci being the member of LAB have proven probiotic strains; therefore, this study was aimed at finding out the potential probiotic candidates from the pool of locally isolated strains. For initial screening, one hundred and twenty-two strains were selected and subjected to different confirmatory and phenotypic tests to choose the best strains that have potential probiotic criteria, i.e., no potential virulence traits, antibiotic resistance, and having tolerance properties. Keeping this criterion, only eleven strains (n = 11) were selected for further assessment. All virulence traits such as production of hemolysin, gelatinase, biofilm, and DNase were performed and not found in the tested strains. The molecular assessment indicates the presence of few virulence-associated genes in Enterococcus faecalis strains with variable frequency. The phenotypic and genotypic assessments of antibiotic resistance profile indicate that the selected strain was susceptible to ten commonly used antibiotics, and there were no transferrable antibiotic resistance genes. The presence of CRISPR-Cas genes also confirmed the absence of antibiotic resistance genes. Various enterocin-producing genes like EntP, EntB, EntA, and EntQ were also identified in the selected strains which make them promising probiotic lead strains. Different tolerance assays like acid, NaCl, and gastric juice tolerance that mimic host conditions was also evaluated by providing artificial conditions. Cellular adhesion and aggregation properties like auto- and co-aggregation were also checked and their results reflect all in the favor of lead probiotic strains.

Antimicrobial overproduction sustains intestinal inflammation by inhibiting Enterococcus colonization

Loss of antimicrobial proteins such as REG3 family members compromises the integrity of the intestinal barrier. Here, we demonstrate that overproduction of REG3 proteins can also be detrimental by reducing a protective species in the microbiota. Patients with inflammatory bowel disease (IBD) experiencing flares displayed heightened levels of secreted REG3 proteins that mediated depletion of Enterococcus faecium (Efm) from the gut microbiota. Efm inoculation of mice ameliorated intestinal inflammation through activation of the innate immune receptor NOD2, which was associated with the bacterial DL-endopeptidase SagA that generates NOD2-stimulating muropeptides. NOD2 activation in myeloid cells induced interleukin-1β (IL-1β) secretion to increase the proportion of IL-22-producing CD4+ T helper cells and innate lymphoid cells that promote tissue repair. Finally, Efm was unable to protect mice carrying a NOD2 gene variant commonly found in IBD patients. Our findings demonstrate that inflammation self-perpetuates by causing aberrant antimicrobial activity that disrupts symbiotic relationships with gut microbes.

Phenotypic and genomic analyses of bacteriocin-producing probiotic Enterococcus faecium EFEL8600 isolated from Korean soy-meju

Enterococcus faecium is a prevalent species found in fermented soybean products, known for its contributions to flavor development and inhibition of pathogenic microorganisms during fermentation. This study aims to provide comprehensive phenotypic and genomic evidence supporting the probiotic characteristics of E. faecium EFEL8600, a bacteriocin-producing strain isolated from Korean soy-meju. Phenotypic analysis revealed that EFEL8600 produced a peptide with inhibitory activity against Listeria monocytogenes, estimated to be 4.6 kDa, corresponding to the size of enterocins P or Q. Furthermore, EFEL8600 exhibited probiotic traits, such as resilience in gastrointestinal conditions, antioxidant and anti-inflammatory activities, and protection of the intestinal barrier. Safety assessments demonstrated no hemolytic and bile salt deconjugation activities. Genomic analysis revealed the presence of several genes associated with probiotic characteristics and bacteriocin production, while few deleterious genes with a low likelihood of expression or transferring were detected. Overall, this study highlights E. faecium EFEL8600 as a potent anti-listeria probiotic strain suitable for use as a starter culture in soymilk fermentation, providing potential health benefits to consumers.

Momordica charantia saponins administration in low-protein-high-carbohydrate diet improves growth, blood biochemical, intestinal health and microflora composition of juvenile common carp (Cyprinus carpio)

An 8-week feeding trial was conducted to explore the feasibility of Momordica charantia saponins (MCS) administration to facilitate the protein-sparing action of high carbohydrate in diets for juvenile common carp (Cyprinus carpio) with initial mass of 5.41 ± 0.02 g. Based on our previous study, four diets with different the ratio of protein and carbohydrate (P/C ratio) were designed: 32%P/40%C, 30%P/43%C, 28%P/46%C, 28%P/46%C supplemented with 0.16% MCS (28%P/46%C + MCS). Each diet treatment was divided into 3 replicates. Results revealed that 30%P/43%C group increased growth performance and intestinal digestion, decreased intestinal inflammation, and optimized the intestinal microbiota compared to 32%P/40%C group, which presented the stronger protein-sparing action of high carbohydrate. But if the P/C ratio reduced to 28%P/46%C or less, the saving action would be restrained. However, compared to the 30%P/43%C and 28%P/46%C groups, 28%P/46%C + MCS group significantly elevated growth performance and activities of digestive enzymes and antioxidative enzymes, whilst the opposite trend occurred in the contents of glucose, triglyceride, total cholesterol, low density lipoprotein cholesterol, blood urea nitrogen, glutamic oxalacetic transaminase, glutamic-pyruvic transaminase and malondialdehyde. In addition, 28%P/46%C + MCS group markedly upregulated the expressions of GH/IGF axis genes, genes involved in protein synthesis, antioxidant genes and anti-inflammatory cytokine, whilst the opposite trend occurred in the expressions of pro-inflammatory cytokines. Moreover, 28%P/46%C + MCS group obtained the remarkably higher Enterococcus proportion and lower Lactococcus proportion compared to the 30%P/43%C and 28%P/46%C groups, whereas the opposite occurred in 30%P/43%C group, which indicated that there existed differences in the improvement mechanism on intestinal microflora composition between MCS and appropriate P/C ratio. Combined with the above mentioned changes in our research, we concluded that 0.16% MCS administration in a 28%P/46%C diet could facilitate the protein-sparing action of high carbohydrate in diets for common carp, which could decrease the 5% dosage of soybean meal and synchronously reduce the 4% crude protein of diets without affecting the growth and immune ability for common carp.

Bacteriocin production and technological properties of Enterococcus mundtii and Enterococcus faecium strains isolated from sheep and goat colostrum

Enterococci are lactic acid bacteria (LAB) that play a role in the aroma formation, maturation, and sensory development of fermented foods such as meat and dairy products. They also contribute to the improvement of the extended shelf life of fermented foods by producing bacteriocin. The aim of this study was to isolate bacteriocin-producing LAB from sheep and goat colostrum, to characterize the bacteriocin-producing strains, and determine the technological properties of the strains. A total of 13 bacteriocin-producing LAB was isolated and identified as 11 Enterococcus mundtii and two Enterococcus faecium. The strains were found to be genetically different from each other by phylogenetic analysis of 16S rRNA gene sequences and random amplified polymorphic-DNA (RAPD-PCR). It has been determined that bacteriocins show activity in a wide pH range and are resistant to heat, lose their activity with proteolytic enzymes and α-amylase, but are resistant to detergents. While the presence of the munKS gene was detected in all of the strains, it was determined that E. faecium HC121.4, HC161.1, E. mundtii HC147.1, HC166.5, and HC166.8 strains contained multiple enterocin genes. Trisin-SDS-PAGE analysis revealed two active protein bands of approximately 5.1 and 5.5 kDa in E. faecium HC121.4 and one active protein band with a weight of approximately 4.96 kDa in other strains. E. mundtii strains and E. faecium HC161.1 were identified as mundticin KS producers, and E. faecium HC121.4 was defined as an enterocin A and B producer. Except for E. mundtii HC166.8, acid production of strains was found to be slow at 6 h and moderate at 24 h. None of them showed extracellular proteolytic and lipolytic activities. It was found that the strains had esterase, esterase lipase, leucine arylamidase, acid phosphatase, and naphthol-AS-Bl-phosphohydrolase activities, while protease activities were low and peptidase activities were high. In conclusion, bacteriocin producer 13 Enterococcus strains isolated from sheep and goat colostrum were found to have the potential to be included in starter culture combinations.

Antimicrobial Resistance, Biofilm Formation, and Virulence Determinants in Enterococcus faecalis Isolated from Cultured and Wild Fish

Fish has always been an integral part of Bengali cuisine and economy. Fish could also be a potential reservoir of pathogens. This study aimed to inquisite the distribution of virulence, biofilm formation, and antimicrobial resistance of Enterococcus faecalis isolated from wild and cultivated fish in Bangladesh. A total of 132 koi fish (Anabas scandens) and catfish (Heteropneustes fossilis) were collected from different markets in the Mymensingh district and analyzed to detect E. faecalis. E. faecalis was detected by conventional culture and polymerase chain reaction (PCR), followed by the detection of virulence genes by PCR. Antibiotic susceptibility was determined using the disk diffusion method, and biofilm-forming ability was investigated by crystal violet microtiter plate (CVMP) methods. A total of 47 wild and 40 cultured fish samples were confirmed positive for E. faecalis by PCR. The CVMP method revealed four per cent of isolates from cultured fish as strong biofilm formers, but no strong producers were found from the wild fish. In the PCR test, 45% of the isolates from the wild and cultivated fish samples were found to be positive for at least one biofilm-producing virulence gene, where agg, ace, gelE, pil, and fsrC genes were detected in 80, 95, 100, 93, and 100% of the isolates, respectively. Many of the isolates from both types of samples were multidrug resistant (MDR) (73% in local fish and 100% in cultured fish), with 100% resistance to erythromycin, linezolid, penicillin, and rifampicin in E. faecalis from cultured fish and 73.08, 69.23, 69.23, and 76.92%, respectively, in E. faecalis from wild fish. This study shows that E. faecalis from wild fish have a higher frequency of virulence genes and biofilm-forming genes than cultivated fish. However, compared to wild fish, cultured fish were found to carry E. faecalis that was more highly multidrug resistant. Present findings suggest that both wild and cultured fish could be potential sources for MDR E. faecalis, having potential public health implications.

Bacteriocin and Antioxidant Production, a Beneficial Properties of Lactic Acid Bacteria Isolated from Fermented Vegetables of Northwest Bulgaria

Lactiplantibacillus plantarum ST01BG, ST07BG, ST10BG, and ST15BG; Latilactobacillus curvatus ST02BG; Lacticaseibacillus paracasei ST04BG; Pediococcus pentosaceus ST05BG; Leuconostoc mesenteroides ST06BG; and Enterococcus faecium ST11BG were isolated from home-made fermented vegetables from Northwest Bulgaria and identified by biochemical, physiological, and biomolecular analyses, including partial 16S rRNA sequencing. The strains were designated as bacteriocin producers and the expressed antimicrobials partially characterized with a focus on their proteinaceous nature, stability to different pH and temperatures. The bacteriocins were effective in inhibiting different strains of Listeria spp., Enterococcus spp. (including vancomycin resistant enterococci) and Staphylococcus spp. These strains can be considered safe, based on the evaluation of hemolytic activity, production of biogenic amines, mucin degradation, antibiotic susceptibility/resistance, and gelatinase enzyme production. Moreover, the strains can be considered potentially beneficial based on their stability and survival under simulated gastrointestinal tract conditions (stomach and duodenum), the production of diacetyl, and specific levels of hydrophobicity. Special attention was given to antioxidant properties (DPPH radical, hydroxyl radical, superoxide anion radical scavenging activity, Fe+2 ion chelating activity, and anti-lipid peroxidation) of the strains. Antioxidant properties were found to be strain specific. The beneficial attributes (antimicrobial and antioxidant) of these cultures to fermented food products may enable the reduction of chemical additives in line with consumers' demand for more natural and chemical-free food commodities.

Evaluation of Enterococcal Probiotic Usage and Review of Potential Health Benefits, Safety, and Risk of Antibiotic-Resistant Strain Emergence

Enterococci are often used in probiotics but can also cause nosocomial infections. As such, enterococcal consumption may have beneficial health effects, but a thorough evaluation of virulence absence and risk of antibiotic resistance spread is needed at the strain level. This article reviewed ten online health product shopping websites in the US. On these websites, 23 probiotic products using enterococci were found across 12 companies. In addition, this article reviewed studies that demonstrated the probiotic potential of enterococcal consumption (e.g., gastrointestinal and respiratory disease, hyperlipidemia alleviation, as well as infection prevention). To investigate the safety aspects of enterococci, the present work examined studies evaluating virulence factors and antibiotic resistance. Furthermore, this article assessed research that explored these virulent factors, specifically in probiotics containing enterococci, as well as the potential transfer mechanism of their antibiotic resistance. Based on reviewed data, enterococcal probiotic consumption has been proven beneficial for conditions or symptoms of multiple diseases without any apparent adverse effects. However, due to the plasmid- or transposon-mediated gene transfer ability of enterococci, surveillance monitoring and further studies regarding enterococcal consumption are warranted. Future studies that identify enterococcal strains safe to use in probiotics without virulence factors and antibiotic resistance are imperative for evidence-based decisions by health organizations and government agencies.

Enhanced Cell Wall and Cell Membrane Activity Promotes Heat Adaptation of Enterococcus faecium

Enterococcus faecium (E. faecium) is widely used in foods and is known as a probiotic to treat or prevent diarrhea in pets and livestock. However, the poor resistance of E. faecium to high temperature processing procedures limits its use. Strain domestication is a low-cost and effective method to obtain high-temperature-resistant strains. In this study, heat treatment was performed from 45 °C to 70 °C and the temperature was gradually increased by 5 °C every 3 days. After domestication, the survival rates of the high temperature adaptation strain RS047-wl under 65 °C water bath for 40 min was 11.5 times higher than WT RS047. Moreover, the saturated fatty acid (SFA) contents in cell membrane and the cell volume significantly increased in the RS047-wl. The combined transcriptomic, metabolomic, and proteomics analysis results showed a significant enhancement of cell wall and membrane synthesis ability in the RS047-wl. In conclusion, one of the main factors contributing to the improved high temperature resistance of RS047-wl was its enhanced ability to synthesize cell wall and membrane, which helped maintain normal cell morphology. Developing a high-temperature-resistant strain and understanding its mechanism enables it to adapt to high temperatures. This lays the groundwork for its future development and application.

Phylogeny, Virulence, and Antimicrobial Resistance Gene Profiles of Enterococcus faecium Isolated from Australian Feedlot Cattle and Their Significance to Public and Environmental Health

The extent of similarity between E. faecium strains found in healthy feedlot beef cattle and those causing extraintestinal infections in humans is not yet fully understood. This study used whole-genome sequencing to analyse the antimicrobial resistance profile of E. faecium isolated from beef cattle (n = 59) at a single feedlot and compared them to previously reported Australian isolates obtained from pig (n = 60) and meat chicken caecal samples (n = 8), as well as human sepsis cases (n = 302). The E. faecium isolated from beef cattle and other food animal sources neither carried vanA/vanB responsible for vancomycin nor possessed gyrA/parC and liaR/liaS gene mutations associated with high-level fluoroquinolone and daptomycin resistance, respectively. A small proportion (7.6%) of human isolates clustered with beef cattle and pig isolates, including a few isolates belonging to the same sequence types ST22 (one beef cattle, one pig, and two human isolates), ST32 (eight beef cattle and one human isolate), and ST327 (two beef cattle and one human isolate), suggesting common origins. This provides further evidence that these clonal lineages may have broader host range but are unrelated to the typical hospital-adapted human strains belonging to clonal complex 17, significant proportions of which contain vanA/vanB and liaR/liaS. Additionally, none of the human isolates belonging to these STs contained resistance genes to WHO critically important antimicrobials. The results confirm that most E. faecium isolated from beef cattle in this study do not pose a significant risk for resistance to critically important antimicrobials and are not associated with current human septic infections.

Investigating the modulatory effects of Moringa oleifera on the gut microbiota of chicken model through metagenomic approach

Introduction

This study aimed to assess the effects of supplementing chicken feed with Moringa oleifera leaf powder, a phytobiotic, on the gastrointestinal microbiota. The objective was to examine the microbial changes induced by the supplementation.

Methods

A total of 40, one-day-old chickens were fed their basal diet for 42 days and then divided into two groups: SG1 (basal diet) and SG2 (basal diet + 10 g/kg Moringa oleifera leaf powder). Metagenomics analysis was conducted to analyze operational taxonomic units (OTUs), species annotation, and biodiversity. Additionally, 16S rRNA sequencing was performed for molecular characterization of isolated gut bacteria, identified as Enterococcus faecium. The isolated bacteria were tested for essential metabolites, demonstrating antibacterial, antioxidant, and anticancer activities.

Results and discussion

The analysis revealed variations in the microbial composition between the control group (SG1) and the M. oleifera-treated group (SG2). SG2 showed a 47% increase in Bacteroides and a 30% decrease in Firmicutes, Proteobacteria, Actinobacteria, and Tenericutes compared to SG1. TM7 bacteria were observed exclusively in the M. oleifera-treated group. These findings suggest that Moringa oleifera leaf powder acts as a modulator that enhances chicken gut microbiota, promoting the colonization of beneficial bacteria. PICRUSt analysis supported these findings, showing increased carbohydrate and lipid metabolism in the M.oleifera-treated gut microbiota.

Conclusion

This study indicates that supplementing chicken feed with Moringa oleifera leaf powder as a phytobiotic enhances the gut microbiota in chicken models, potentially improving overall health. The observed changes in bacterial composition, increased presence of Bacteroides, and exclusive presence of TM7 bacteria suggest a positive modulation of microbial balance. The essential metabolites from isolated Enterococcus faecium bacteria further support the potential benefits of Moringa oleifera supplementation.

Safety assessment of Enterococcus lactis based on comparative genomics and phenotypic analysis

Enterococcus faecium is sometimes used in food production; however, its acquisition of antibiotic resistance has become an alarming health concern. The E. lactis species is closely related to E. faecium and has good probiotic potential. This study aimed to investigate the antibiotic resistance of E. lactis. We analyzed the antibiotic resistance phenotype and whole-genome sequences of 60 E. lactis isolates (23, 29, and 8 isolates from dairy products, Rice wine Koji, and human feces, respectively). These isolates showed varying degree of resistance to 13 antibiotics, and were sensitive to ampicillin and linezolid. The E. lactis genomes carried only a subset of commonly reported antibiotic resistance genes (ARGs) in E. faecium. Five ARGs were detected across the investigated E. lactis, including two universally present genes (msrC and AAC(6')-Ii) and three rarely detected ARGs (tet(L), tetM, and efmA). To identify other undescribed antibiotic resistance-encoding genes, a genome-wide association study was performed, returning 160 potential resistance genes that were associated with six antibiotics, namely chloramphenicol, vancomycin, clindamycin, erythromycin, quinupristin-dalfopristin, and rifampicin. Only around one-third of these genes encode known biological functions, including cellular metabolism, membrane transport, and DNA synthesis. This work identified interesting targets for future study of antibiotic resistance in E. lactis. The fact that the lower number of ARGs present in E. lactis supports that it may be an alternative to E. faecalis for use in the food industry. Data generated in this work is of interest to the dairy industry.

Therapeutic and prophylactic effects of oral administration of probiotic Enterococcus faecium Smr18 in Salmonella enterica-infected mice

Salmonella enterica serotype Typhi causes chronic enteric fever known as typhoid. Prolonged treatment regimen used for the treatment of typhoid and indiscriminate use of antibiotics has led to the emergence of resistant strains of S. enterica that has further increased the severity of the disease. Therefore, alternative therapeutic agents are urgently required. In this study, probiotic and enterocin-producing bacteria Enterococcus faecium Smr18 was compared for both its prophylactic and therapeutic efficacy in S. enterica infection mouse model. E. faecium Smr18 possessed high tolerance to bile salts and simulated gastric juice, as treatment for 3 and 2 h resulted in 0.5 and 0.23 log₁₀ reduction in the colony forming units, respectively. It exhibited 70% auto aggregation after 24 h of incubation and formed strong biofilms at both pH 5 and 7. Oral administration of E. faecium in BALB/c mice infected with S. enterica significantly (p < 0.05) reduced the mortality of the infected mice and prevented the weight loss in mice. Administration of E. faecium prior to infection inhibited the translocation of S. enterica to liver and spleen, whereas, its administration post-infection completely cleared the pathogen from the organs within 8 days. Further, in both pre- and post-E. faecium-treated infected groups, sera levels of liver enzymes were restored back to normal; whereas the levels of creatinine, urea and antioxidant enzymes were significantly (p < 0.05) reduced compared to the untreated-infected group. E. faecium Smr18 administration significantly increased the sera levels of nitrate by 1.63-fold and 3.22-fold in pre- and post-administration group, respectively. Sera levels of interferon-γ was highest (tenfold) in the untreated-infected group, whereas the levels of interleukin-10 was highest in the post-infection E. faecium-treated group thereby indicating the resolution of infection in the probiotic-treated group, plausibly due to the increased production of reactive nitrogen intermediates.

Apoptosis induction in cancer cell lines and anti-inflammatory and anti-pathogenic properties of proteinaceous metabolites secreted from potential probiotic Enterococcus faecalis KUMS-T48

Potential probiotic Enterococcus faecalis KUMS-T48, isolated from a kind of Iranian traditional dairy product (Tarkhineh), was assessed for its anti-pathogenic, anti-inflammatory and anti-proliferative properties against HT-29 and AGS cancer cell lines. This strain showed strong effects on Bacillus subtilis and Listeria monocytogenes and moderate effect on Yersinia enterocolitica, while indicated weak effect on Klebsiella pneumoniae and Escherichia coli. Also, neutralizing the cell-free supernatant and treating it with catalase and proteinase K enzymes reduced the antibacterial effects. Similar to Taxol, the cell-free supernatant of E. faecalis KUMS-T48 inhibited the in vitro proliferation of both cancer cells in a dose-dependent manner, but unlike Taxol, they had no activity against normal cell line (FHs-74). Pronase-treatment of the CFS of E. faecalis KUMS-T48 abrogated its anti-proliferative capacity, thereby showing the proteinaceous nature of the cell-free supernatant. Further, induction of apoptosis-based cytotoxic mechanism by E. faecalis KUMS-T48 cell-free supernatant is related to anti-apoptotic genes ErbB-2 and ErbB-3, which is different from Taxol's apoptosis induction (intrinsic mitochondria apoptosis pathway). Also, as evidenced by a decline in interleukin 1β inflammation-promoting gene expression and a rise in the anti-inflammatory interleukin-10 gene expression in the HT-29 cell line, probiotic E. faecalis KUMS-T48 cell-free supernatant demonstrated a significant anti-inflammatory impact.

Prevalence of Vancomycin-resistant enterococci (VRE) in Egypt (2010-2022): a systematic review and meta-analysis

BACKGROUND

Vancomycin-resistant Enterococci (VRE) represent a critical medical and public health concerns due to their association with serious nosocomial infections and a high risk of mortality. We aimed to reveal the pooled prevalence of VRE and antimicrobial resistance profiles among enterococci clinical isolates in Egypt.

METHODS

A PubMed, Scopus, Google Scholar, and Web of Science literature search was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Only published studies documenting the prevalence of VRE between 2010 and 2022 were included. Using the random effects model and the 95% confidence intervals, the pooled estimate of VRE was calculated by MedCalc Version 20.113. Cochran's Q and I² tests were used to evaluate the degree of heterogeneity, and publication bias was examined by visually examining the funnel plot and its associated tests (Begg's and Egger's tests).

RESULTS

The pooled prevalence of VRE among enterococci clinical isolates in Egypt was estimated to be 26% (95% CI 16.9 to 36.3). E. faecalis had a greater pooled prevalence than E. faecium, with 61.22% (95% CI 53.65 to 68.53) and 32.47% (95% CI 27 to 38.2), respectively. The VanA gene is more frequent than the VanB gene among VRE, with a pooled prevalence of 63.3% (95% CI 52.1 to 73.7) and 17.95% (95% CI 7.8 to 31), respectively. The pooled resistance rate of linezolid was substantially lower than that of ampicillin and high-level gentamicin (HLG) 5.54% (95% CI 2.33 to 10%), 65.7% (95% CI 50.8 to 79.2%), and 61.1% (95% CI 47.4 to 73.9), respectively.

CONCLUSION

The prevalence of VRE is alarmingly high in Egypt. It is imperative that antimicrobial stewardship activities and infection control programs are strictly adhered to and implemented to prevent further escalation of the problem.

Isolation of lectin from Musa acuminata for its antibiofilm potential against Methicillin-resistant Staphylococcus aureus and its synergistic effect with Enterococcus species

Methicillin resistant Staphylococcus aureus (MRSA) is an emerging pathogen posing a considerable burden on the healthcare system due to its involvement in skin and soft tissue infections (SSTIs). Lectins are carbohydrate binding proteins found ubiquitously in animals, plants and microorganisms. Extraction and isolation of proteins from Musa acuminata were performed by using Affinity chromatography with Sephadex G 75 to determine antibiofilm activity against MRSA. Enterococcus strains obtained from dairy products, beans and vegetables were also screened for its potential to inhibit growth and biofilm formation of MRSA by using 96 well microtiter plates. Synergistic effect of cell free supernatant of Enterococcus with proteins from ripe banana were also tested. BanLec was successfully isolated and appeared as 15 KDa band after SDS-PAGE (15%) while multiple bands of unbound protein fractions were observed. The unbound fractions showed inhibition of planktonic cells and biofilm but BanLec exhibited no significant effect. The CFS of Enterococcus faecium (LCM002), Enterococcus lactis (LCM003) and Enterococcus durans (LCM004 and LCM005) displayed antagonistic effects against pathogen. The synergistic effect of CFS from E. lactis (LCM003) and unbound proteins showed inhibition of biofilm and pathogenic growth. This study demonstrates the use of Enterococcus species and plant proteins against pathogens and results suggested that it can inhibit the growth of resistant strains of Staphylococcus aureus and their synergistic effect has opened new ways to tackle emerging resistance. Furthermore, after assessment of Enterococcus as probiotics, this could be used in food industries as well as in treatment of severe skin infections.

Comprehensive genomic analysis of hypocholesterolemic probiotic Enterococcus faecium LR13 reveals unique proteins involved in cholesterol-assimilation

Hypercholesterolemia is a major risk factor for cardiovascular diseases (CVDs). Chemotherapeutic agents for CVDs exhibit several side effects. Specific probiotics with hypocholesterolemic effects can be safe and effective alternatives to chemotherapeutics. Here, we have analyzed and compared the genome of a novel rhizospheric Enterococcus faecium LR13 cholesterol-assimilating probiotic with other probiotic/pathogenic E. faecium strains to discern genetic factors underlying probiotic efficacy and cholesterol-assimilation. Genomic analyses of E. faecium probiotic strains revealed that LR13 and WEFA23 (cholesterol-assimilating probiotics) harbored 21 unique proteins absent in non-cholesterol-assimilating probiotics. Of these, 14 proteins could directly help in cholesterol-assimilation by producing short chain fatty acids, lipid (sterol) transport and membrane stabilization, and bile salt hydrolase activity. This suggests that cholesterol-assimilation is an intrinsic, strain-specific trait exhibited by probiotics with a specific genetic constitution. Moreover, the unique proteins identified in this study can serve as biomarkers for discerning/characterizing cholesterol-assimilating probiotics as novel biotherapeutics against CVDs.

Microbiological quality and antimicrobial resistance of Bacteria species recovered from ready-to-eat food, water samples, and palm swabs of food vendors in Accra, Ghana

This study sought to investigate microbial quality and antimicrobial resistance of bacteria species from Ready-to-Eat (RTE) food, water, and vendor palm swab samples. Between 2019 and 2020, RTE food, water and vendor palm swab samples were collected from food vending sites in Accra, Ghana. Samples were cultured and confirmed using the Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF). Antimicrobial susceptibility testing (AST) was conducted using disk diffusion method. Beta-lactamase and Diarrheagenic Escherichia coli (DEC) genes were determined using Polymerase Chain Reaction (PCR). Total plate count (TPC) and Total coliform count (TCC) were performed on food and water samples. In total, 179 RTE food, 72 water and 10 vendor palm swab samples were collected. Enterobacter spp. (16.8 %), Citrobacter spp. (10.1 %), Enterococcus faecalis (7.8 %), Pseudomonas spp. (6.7 %) and Klebsiella pneumoniae (4.0 %) occurred in food. Isolates from water and palm were Klebsiella pneumoniae (20.8 %), Aeromonas spp. (16.7 %) and Enterobacter cloacae (11.1 %). Resistance to Amoxicillin-clavulanate, Tetracycline, Azithromycin, Sulfamethoxazole-trimethoprim, and Nitrofurantoin were common among Enterobacterales. High mean TPC and TCC showed in some RTE food and different water types used in vending depicting their unsafe condition for consumption and usage. The bla_SHV and bla_TEM genes were present in some Enterobacterales from food and water. The lt gene was identified in two food samples. AMR organisms associated with nosocomial infections in the samples investigated, calls for continuous surveillance in the food industry in Ghana. Also, the unsafe outcome of RTE food and water depicts the need for the enforcement of Ghana's food safety laws.

Pea (Pisum sativum L.) pod powder as a potential enhancer of probiotic Enterococcus faecium M74 in ice cream and its physicochemical, structural, and sensory effects

BACKGROUND

In this study, pea (Pisum sativum L.) pod powder (PPP) was incorporated (1% and 3% w/w) into a probiotic ice cream formulation containing Enterococcus faecium M74 to investigate the potential effect of PPP on the probiotic survivability in the ice cream throughout 60 days of frozen storage. Moreover, the produced symbiotic ice creams were evaluated for their physiochemical properties, stability, and sensory acceptability.

RESULTS

Incorporation of PPP into ice cream caused significantly (P < 0.05) increased protein and ash content and lower pH values. Besides that, the addition of PPP resulted in ice creams with higher hardness and lower overrun. A significant diminishing was observed in the melting rates of the ice creams as the percentage of PPP increased and storage time progressed. Ice cream with PPP presented lower lightness and higher greenness and yellowness compared with control. All ice creams had viable counts of E. faecium M74 of ≥6 log cfu g-1 during storage and provided the number of viable cells that the probiotic product should contain. On day 60, the viability of E. faecium M74 in ice cream containing 1% PPP (7.64 ± 0.02) was higher than the control (7.28 ± 0.00). Sensory analyses revealed that there was no statistical difference in ice cream with 1% PPP and the control without PPP in terms of general acceptability.

CONCLUSION

These results suggest that pea pods, which is a waste product of the pea industry and obtained at zero cost, could be used as a potential prebiotic and an agent to improve technological properties of dairy products. © 2022 Society of Chemical Industry.

Diet-microbiota crosstalk and immunity to helminth infection

Helminths are large multicellular parasites responsible for widespread chronic disease in humans and animals. Intestinal helminths live in close proximity with the host gut microbiota and mucosal immune network, resulting in reciprocal interactions that closely influence the course of infections. Diet composition may strongly regulate gut microbiota composition and intestinal immune function and therefore may play a key role in modulating anti-helminth immune responses. Characterizing the multitude of interactions that exist between different dietary components (e.g., dietary fibres), immune cells, and the microbiota, may shed new light on regulation of helminth-specific immunity. This review focuses on the current knowledge of how metabolism of dietary components shapes immune response during helminth infection, and how this information may be potentially harnessed to design new therapeutics to manage parasitic infections and associated diseases.

Butyrogenic effect of galactosyl and mannosyl carbohydrates and their regulation on piglet intestinal microbiota

Diarrhea is a global problem that causes economic losses in the pig industry. There is a growing attention on finding new alternatives to antibiotics to solve this problem. Hence, this study aimed to compare the prebiotic activity of low-molecular-weight hydrolyzed guar gum (GMPS) with commercial manno-oligosaccharide (MOS) and galacto-oligosaccharide (GOS). We further identified their combined effects along with probiotic Clostridium butyricum on regulating the intestinal microbiota of diarrheal piglet by in vitro fermentation. All the tested non-digestible carbohydrates (NDCs) showed favorable short-chain fatty acid-producing activity, and GOS and GMPS showed the highest production of lactate and butyrate, respectively. After 48 h of fermentation, the greatest enhancement in the abundance of Clostridium sensu stricto 1 was observed with the combination of GMPS and C. butyricum. Notably, all the selected NDCs significantly decreased the abundances of pathogenic bacteria genera Escherichia-Shigella and Fusobacterium and reduced the production of potentially toxic metabolites, including ammonia nitrogen, indole, and skatole. These findings demonstrated that by associating with the chemical structure, GMPS exhibited butyrogenic effects in stimulating the proliferation of C. butyricum. Thus, our results provided a theoretical foundation for further application of galactosyl and mannosyl NDCs in the livestock industry. KEY POINTS: • Galactosyl and mannosyl NDCs showed selective prebiotic effects. • GMPS, GOS, and MOS reduced pathogenic bacteria and toxic metabolites production. • GMPS specifically enhanced the Clostridium sensu stricto 1 and butyrate production.

Analysis of CRISPR-Cas Loci and their Targets in Levilactobacillus brevis

The CRISPR‒Cas system acts as a bacterial defense mechanism by conferring adaptive immunity and limiting genetic reshuffling. However, under adverse environmental hazards, bacteria can employ their CRISPR‒Cas system to exchange genes that are vital for adaptation and survival. Levilactobacillus brevis is a lactic acid bacterium with great potential for commercial purposes because it can be genetically manipulated to enhance its functionality and nutritional value. Nevertheless, the CRISPR‒Cas system might interfere with the genetic modification process. Additionally, little is known about the CRISPR‒Cas system in this industrially important microorganism. Here, we investigate the prevalence, diversity, and targets of CRISPR‒Cas systems in the genus Levilactobacillus, further focusing on complete genomes of L. brevis. Using the CRISPRCasFinder webserver, we identified 801 putative CRISPR-Cas systems in the genus Levilactobacillus. Further investigation focusing on the complete genomes of L. brevis revealed 54 putative CRISPR-Cas systems. Of these, 46 were orphan CRISPRs, and eight were CRISPR‒Cas systems. The type II-A CRISPR‒Cas system is the most common in Levilactobacillus and L. brevis complete genomes. Analysis of the spacer's target showed that the CRISPR‒Cas systems of L. brevis mainly target the enterococcal plasmids. Comparative analysis of putative CRISPR-Cas loci in Levilactobacillus brevis.

Vancomycin-Resistant Enterococcus faecium and the emergence of new Sequence Types associated with Hospital Infection

Enterococcus faecium is a major cause of vancomycin-resistant enterococcal (VRE) infection. New variants of the pathogen have emerged and become dominant in healthcare settings. Two such examples, vanB ST796 and vanA ST1421 sequence types, originally arose in Australia and proceeded to cause VRE outbreaks in other countries. Of concern is the detection of a vancomycin variable enterococcal (VVE) variant of ST1421 in Europe that exhibits a vancomycin-susceptible phenotype but which can revert to resistant in the presence of vancomycin. The recent application of genome sequencing for increasing our understanding of the evolution and spread of VRE is also explored here.

Antimicrobial Susceptibility Profile of Pathogenic and Commensal Bacteria Recovered from Cattle and Goat Farms

The use of antibiotics in food animals results to antimicrobial resistant bacteria that complicates the ability to treat infections. The purpose of this study was to investigate the prevalence of pathogenic and commensal bacteria in soil, water, manure, and milk from cattle and goat farms. A total of 285 environmental and 81 milk samples were analyzed for Enterobacteriaceae by using biochemical and PCR techniques. Susceptibility to antibiotics was determined by the Kirby-Bauer disk diffusion technique. A total of 15 different Enterobacteriaceae species were identified from goat and cattle farms. Manure had significantly higher (p < 0.05) Enterobacteriaceae (52.0%) than soil (37.2%), trough water (5.4%), and runoff water (5.4%). There was a significant difference (p < 0.05) in Enterobacteriaceae in goat milk (53.9%) and cow milk (46.2%). Enterobacteriaceae from environment showed 100% resistance to novobiocin, erythromycin, and vancomycin E. coli O157:H7, Salmonella spp., Enterococcus spp., and Listeria monocytogenes displayed three, five, six, and ten. AMR patterns, respectively. NOV-TET-ERY-VAN was the most common phenotype observed in all isolates. Our study suggest that cattle and goat farms are reservoirs of multidrug-resistant bacteria. Food animal producers should be informed on the prudent use of antimicrobials, good agricultural practices, and biosecurity measures.

Isolation and phenotypic characterization of bacteriophage SA14 with lytic- and anti-biofilm activity against multidrug-resistant Enterococcus faecalis

Background

Antimicrobial resistance is a growing global health concern demanding more attention and action at the international-, national- and regional levels. In the present study, bacteriophage was sought as a potential alternative to traditional antibiotics.

Results

Vancomycin-resistant Enterococcus faecalis was isolated from a urine sample. Partial 16S rRNA-gene sequencing and VITEK®2 system were employed for its identification, biochemical characterization, and antibiotic susceptibility testing. The isolate was resistant to eight antibiotics (out of 11): vancomycin, gentamicin (high-level synergy), streptomycin (high-level synergy), ciprofloxacin, levofloxacin, erythromycin, quinupristin/dalfopristin, and tetracycline. Bacteriophage SA14 was isolated from sewage water using the multidrug-resistant isolate as a host. Transmission electron micrographs revealed that phage SA14 is a member of the Siphoviridae family displaying the typical circular head and long non-contractile tail. The phage showed characteristic stability to a wide range of solution pH and temperatures, with optimal stability at pH 7.4 and 4 °C, while showing high specificity toward their host. Based on the one-step growth curve, the phage's latent period was 25 min, and the burst size was 20 PFU/ml. The lytic activity of phage SA14 was evaluated at various multiplicities of infection (MOI), all considerably suppressed the growth of the host organism. Moreover, phage SA14 displayed a characteristic anti-biofilm activity as observed by the reduction in adhered biomass and -viable cells in the pre-formed biofilm by 19.1-fold and 2.5-fold, respectively.

Conclusion

Phage therapy can be a valuable alternative to antibiotics against multi-drug resistant microorganisms.

Antimicrobial overproduction sustains intestinal inflammation by inhibiting Enterococcus colonization

Loss of antimicrobial proteins such as REG3 family members compromises the integrity of the intestinal barrier. Here, we demonstrate that overproduction of REG3 proteins can also be detrimental by reducing a protective species in the microbiota. Patients with inflammatory bowel disease (IBD) experiencing flares displayed heightened levels of secreted REG3 proteins that mediated depletion of Enterococcus faecium ( Efm ) from the gut microbiota. Efm inoculation of mice ameliorated intestinal inflammation through activation of the innate immune receptor NOD2, which was associated with the bacterial DL-endopeptidase SagA. Microbiota sensing by NOD2 in myeloid cells mediated IL-1β secretion and increased the proportion of IL-22-producing CD4 + T helper cells and innate lymphoid cells. Finally, Efm was unable to protect mice carrying a NOD2 gene variant commonly found in IBD patients. Our findings demonstrate that inflammation self-perpetuates by causing aberrant antimicrobial activity that disrupts symbiotic relationships with gut microbes.