Lactobacillus reuteri and Enterococcus faecium from Poultry Gut Reduce Mucin Adhesion and Biofilm Formation of Cephalosporin and Fluoroquinolone-Resistant Salmonella enterica

Limosilactobacillus reuteri DSM17938 Attenuates Neuroinflammatory Responses After Spinal Cord Injury by Modulating Tryptophan Metabolism

Spinal cord injury (SCI) disrupts gut flora and exacerbates neuroinflammation. Evidence supports the important role of the intestinal microbiota in SCI. This study evaluated the neuroprotective effect of Limosilactobacillus reuteri (L. reuteri) DSM 17938 on SCI and its potential anti-inflammatory mechanism. The intestinal microbiota was disorganised following SCI, with a significant decrease in the abundance of probiotic bacteria such as L. reuteri. L. reuteri DSM17938 treatment improved the spinal cord pathology and enhanced locomotor functional recovery in SCI-model rats. Moreover, it modulated tryptophan metabolism by promoting indole-3-carboxaldehyde production. In addition, L. reuteri DSM17938 inhibits polarization of M1 microglia and reduces the production of IL-6, IL-1 β, and TNF-α in spinal cord injury to alleviate neuroinflammation. It also activates aryl hydrocarbon receptor (AhR) signalling via upregulating AhR and CYP1A1 expression, promoting tight junction protein synthesis. In summary, L. reuteri DSM17938 promotes SCI recovery by modulating tryptophan metabolism to activate AhR signalling and intestinal barrier repair to attenuate spinal cord M1 microglial activation and neuroinflammation, suggesting a strategy for clinical adjuvant SCI treatment.

Ecological prevalence and genomic characterization of Salmonella isolated from selected poultry farms in Jiangxi province, China

Non-typhoidal Salmonella (NTS), particularly antimicrobial-resistant serovars, remains the major source of foodborne bacterial illnesses. Raw chicken is the leading cause of human salmonellosis. In this study, we evaluated the prevalence, antimicrobial resistance profiles, and genomic features of 143/1,800 (7.94%) Salmonella strains isolated from poultry farms in five major regions of Jiangxi province, China, between 2022 and 2023 using Whole genome sequencing (WGS). Among Salmonella isolates, the most common serovars were Infantis (ST32) and Enteritidis (ST11). Resistance to amoxicillin and tetracycline was the most prevalent, with 60.84% of Salmonella isolates exhibiting a multi-drug resistance (MDR) pattern. The detection of antimicrobial-resistant genes (ARGs) examined was aligned with the resistant phenotypes found. A total of 61 ARGs were identified, with aph(3')-Ia, qnrS1, aph(3'')-Ib, and tetA being the prominent ARGs. Furthermore, 24 beta-lactam genes were also identified, including blaTEM, blaSHV, and blaCTX-M. The number of ARGs and the distribution of serovars varied according to the year, farms, and cities. Salmonella isolates carried 13 heavy metal resistance genes (HMRGs) and two biocide resistance genes, with pcoS being the most prevalent. A total of 145 virulence genes and 19 plasmids were found, with serovars Infantis and Enteritidis having the most virulence genes. The high occurrence of MDR Salmonella in this study, particularly carrying numerous mobile genetic elements (MGEs), posed a serious threat to food safety and public health, emphasizing the need to improve poultry farm hygiene to decrease contamination and transmission.

The dual action of probiotic lactobacilli in suppressing virulence and survival of Arcobacter butzleri

Arcobacter butzleri is a widely distributed foodborne and waterborne pathogen, increasingly recognized as an emerging enteropathogen. Understanding its survival mechanisms and interactions with probiotics is crucial for developing targeted intervention strategies. A. butzleri must withstand various hostile conditions to successfully colonize the gastrointestinal tract, including inhibition by probiotics, such as Limosilactobacillus reuteri, Lactobacillus acidophilus and Lactiplantibacillus plantarum. Thus, this study aimed to assess the survival of A. butzleri under acidic conditions and determine its minimum inhibitory concentration (MIC) for bile salts. Additionally, the antimicrobial potential of the lactobacilli strains was evaluated by analysing the effects of their culture-free supernatant (CFS) on A. butzleri growth, coculture interactions, and biofilm formation. The influence of lactobacilli on A. butzleri was further investigated through competition, displacement and exclusion assays using Caco-2 cell models. The results indicate that lactobacilli strains exhibit tolerance to acidic environments and physiological bile salt concentrations, whereas A. butzleri was more susceptible to acidic stress. The antagonistic effect of lactobacilli was evidenced by growth inhibition of A. butzleri in the presence of CFS or during coculture. However, CFS from certain lactobacilli strains was found to enhance biofilm formation, highlighting potential consequences. Furthermore, while lactobacilli did not demonstrate significant antagonistic effects in competition assays, they effectively displaced and excluded A. butzleri in the Caco-2 infection model. Overall, these findings suggest that probiotic lactobacilli can inhibit A. butzleri growth, yet their impact on its virulence remains uncertain. This underscores the need for strain-specific probiotic selection to effectively target this pathogen and emphasizes that not every probiotic contribute to the prevention of A. butzleri infections.

Engineering Useful Microbial Species for Pharmaceutical Applications

Microbial engineering has made a significant breakthrough in pharmaceutical biotechnology, greatly expanding the production of biologically active compounds, therapeutic proteins, and novel drug candidates. Recent advancements in genetic engineering, synthetic biology, and adaptive evolution have contributed to the optimization of microbial strains for pharmaceutical applications, playing a crucial role in enhancing their productivity and stability. The CRISPR-Cas system is widely utilized as a precise genome modification tool, enabling the enhancement of metabolite biosynthesis and the activation of synthetic biological pathways. Additionally, synthetic biology approaches allow for the targeted design of microorganisms with improved metabolic efficiency and therapeutic potential, thereby accelerating the development of new pharmaceutical products. The integration of artificial intelligence (AI) and machine learning (ML) plays a vital role in further advancing microbial engineering by predicting metabolic network interactions, optimizing bioprocesses, and accelerating the drug discovery process. However, challenges such as the efficient optimization of metabolic pathways, ensuring sustainable industrial-scale production, and meeting international regulatory requirements remain critical barriers in the field. Furthermore, to mitigate potential risks, it is essential to develop stringent biocontainment strategies and implement appropriate regulatory oversight. This review comprehensively examines recent innovations in microbial engineering, analyzing key technological advancements, regulatory challenges, and future development perspectives.

Intestinal microbiota composition in broilers fed protein-free or casein-based diets

Growing broiler chickens of the Cobb500 strain were used to determine the effects on intestinal microbiota composition of a protein-free (PF) diet as compared to a diet based in casein (CAS) as the only protein source. CAS was formulated to contain the same amount of protein (190 g kg-1) as a commercial Maize-soy diet which was used as a practical reference. The ileal AA flow (g kg-1 dry matter intake) was significantly higher (P < 0.001) than PF in birds fed protein containing diets (CAS or Maize-soy). Taken as a whole (discriminant and ANOSIM analysis), the intestinal (ileal and caecal contents and ileal tissue) microbiota composition of PF and CAS were significantly (P < 0.001) different from Maize-soy and not different from each other in some cases. RT-qPCR and sequencing analysis of the ileal and caecal microbiota revealed significant (P < 0.05) differences in a number of bacterial groups between broilers fed PF, CAS or Maize-soy diets. The main result was that the lack of protein in the intestinal medium of PF birds resulted in a drop of Lactobacillus spp. counts (on average, 43 in PF vs 1,734 in the Maize-soy diet) and increased Enterobacteriaceae (on average, 419 in PF vs 172 in the Maize-soy diet) and other potentially pathogenic bacterial groups (in both intestinal contents and tissue). Thus, the lack of protein in the intestinal medium of PF birds resulted in a microbiota composition compatible with a pro-inflammatory state, and this effect was somewhat less marked in birds fed CAS. The results reported here suggest that the adverse effects on microbiota composition in broilers fed CAS were less marked than in those fed PF, which would be in line with a preferential use of a highly digestible protein containing diet to determine endogenous AA excretion instead of a PF diet.

Imidazolium, pyridinium and pyrazinium based ionic liquids with octyl side chains as potential antibacterial agents against multidrug resistant uropathogenic E. coli

Urinary tract infections (UTIs) are the second most prevalent infectious disease with E. coli being the most common etiological agent behind these infections, affecting more than 150 million people globally each year. In recent decades, the emergence of multi-drug resistant (MDR) pathogens has rapidly escalated. To combat antimicrobial resistance (AMR), it is important to synthesize new biologically effective alternatives like ionic liquids (ILs) to control the bacterial infection and their spread. Ionic liquids are poorly coordinated organic salts characterized by melting points typically below 100 °C. The ability of ILs to form anionic and cationic interactions contributes to their versatile chemical, physical and biological attributes. In the present study, a total of 9 previously chemically synthesized and characterized ILs were used. For exploration of their antibacterial potential against the urinary tract infections (UTIs) caused by MDR Uropathogenic E. coli (UPEC) strains, in vitro and in vivo evaluation of ILs were performed. ILs showed pronounced zone of inhibition (ZOI), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 29.5 mm, 3.81 μM and 5.08 μM by agar disk diffusion and broth micro-dilution methods, respectively. Scanning electron microscopy results depicted substantial morphological changes in UPEC biofilm formation ascertaining antibiofilm potential of tested ILs. Moreover, ILs showed exceptional antioxidant potential depicted by DPPH assay along with low cytotoxic effect toward mammalian cell lines (NB4), red blood cells and whole blood. Furthermore, the gene expression analysis results justified the antibacterial potential of ILs showing down-regulation of fimH, uvrY and up-regulation of csrA gene in UPEC after ILs treatment. In vivo dermal sensitivity assessment also established their non-cytotoxic behavior. In silico analysis validated these results, with the majority of the compounds exhibiting moderate to good absorption.Due to remarkable antibacterial and antioxidant potential and negligible cytoxicity, it could be inferred that ILs could serve as novel antimicrobial alternative agents in the treatment of UTIs.

Whole-genome sequencing of three ciprofloxacin-resistant Salmonella Reading (ST93) strains, an emerging Salmonella serovar in the poultry sector of Pakistan

In this study, we performed whole-genome sequencing of three ciprofloxacin-resistant Salmonella Reading strains isolated from poultry meat. Genomes of S. Reading strains contained an average of 4.81 Mbp size with 52.1% GC. The isolates exhibited blaOXA-10, aac [6']-Iaa, aadA1, cmlA1, qnrS1, and tetA resistance genes and IncX1 and IncX2 plasmids.

The Comparative Study of the Antioxidant and Antibacterial Effects of Propolis Extracts in Veterinary Medicine

Antimicrobial resistance (AMR) is one of the biggest threats to human and animal health. Efforts to combat AMR include the introduction of antimicrobial drugs as alternative treatment options. To contribute to an effective plan for the treatment of infectious diseases caused by bacteria, the development of new antimicrobial agents is increasingly being explored. Propolis has garnered significant attention from both scientists and industry due to its extensive spectrum of biological activity. The growing interest in polyphenols of natural origin and their plant sources further encourages the investigation of their chemical composition and biological effects. Propolis serves as a rich source of phenolic compounds. Baltic region propolis, classified as poplar-type propolis, was selected for this study, and extracts were prepared using raw propolis materials from various Baltic countries. The production of liquid extracts utilized a combination of 70 percent ethanol, a mixture of water and poloxamer P407, and DES (deep eutectic solvent). The research aims to produce liquid propolis extracts using different solvents and to assess their chemical composition, antioxidant, and antimicrobial activity against different veterinary pathogens. Antioxidant activity was evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl), revealing antioxidant activity in all extracts, with results correlating with the total phenolic compound content. It was found that p-coumaric acid predominated in the studied propolis extracts (in ethanol extracts 1155.90-1506.65 mg/g, in DES extracts 321.13-954.76 mg/g, and in polymeric extracts 5.34-30.80 mg/g), with smaller amounts of ferulic acid and vanillin detected. Clinical and reference bacterial strains were collected from the Lithuanian University of Health Sciences, the Academy of Veterinary Medicine, and the Institute of Microbiology and Virology. To effectively treat bacterial infections, the antimicrobial activity of propolis extracts was tested against six pathogenic bacterial species and one pathogenic fungus (S. aureus, S. agalactiae, B. cereus, E. faecalis, E. coli, P. aeruginosa, and C. albicans). Antimicrobial activity studies demonstrated that DES propolis extracts exhibited stronger antimicrobial activity compared to ethanolic propolis extracts. The minimum inhibitory concentration (MIC) values of DES propolis extracts against the tested strains ranged between 50 and 1000 μg/mL. Considering the study results, it can be concluded that propolis from the Baltic region is abundant in phenolic compounds exhibiting antioxidant and antibacterial activities.

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.

Emerging Approaches for Mitigating Biofilm-Formation-Associated Infections in Farm, Wild, and Companion Animals

The importance of addressing the problem of biofilms in farm, wild, and companion animals lies in their pervasive impact on animal health and welfare. Biofilms, as resilient communities of microorganisms, pose a persistent challenge in causing infections and complicating treatment strategies. Recognizing and understanding the importance of mitigating biofilm formation is critical to ensuring the welfare of animals in a variety of settings, from farms to the wild and companion animals. Effectively addressing this issue not only improves the overall health of individual animals, but also contributes to the broader goals of sustainable agriculture, wildlife conservation, and responsible pet ownership. This review examines the current understanding of biofilm formation in animal diseases and elucidates the complex processes involved. Recognizing the limitations of traditional antibiotic treatments, mechanisms of resistance associated with biofilms are explored. The focus is on alternative therapeutic strategies to control biofilm, with illuminating case studies providing valuable context and practical insights. In conclusion, the review highlights the importance of exploring emerging approaches to mitigate biofilm formation in animals. It consolidates existing knowledge, highlights gaps in understanding, and encourages further research to address this critical facet of animal health. The comprehensive perspective provided by this review serves as a foundation for future investigations and interventions to improve the management of biofilm-associated infections in diverse animal populations.

Regulation of the growth performance and the gastrointestinal microbiota community by the addition of defective pear fermentation to feed of small-tailed Han sheep

This study investigated the effects of defective pear fermentation (DPF) diets on growth performance and gastrointestinal microbial communities in 60 healthy male small-tailed Han sheep, aged 90 days. The sheep were randomly divided into four groups, each consisting of three replicates with five sheep per replicate. Initially, all groups received a basal diet for seven days during the adaptation stage. Subsequently, for 60 days, group C (control) was fed a basal diet, group X received a basal diet with 2% DPF, group Y had a basal diet with 4% DPF, and group Z was fed a basal diet with 6% DPF. The results indicated that group Y experienced a significant increase in average daily gain (ADG) and average daily feed intake (ADFI). The addition of DPF significantly elevated the levels of GSH-Px and notably reduced MDA content compared to group C. Analysis of gastrointestinal microbiota showed that groups receiving DPF had increased relative abundances of Lachnospiraceae_NK3A20_group, norank_f p-2534-18B5_gut_group, Acetitomaculum, Actinobacteriota, Bacteroidota and Ruminococcus_gauvreauii_group, and decreased abundances of Proteobacteria, Prevotella, Staphylococcus, and Psychrobacter compared to group C. Group X exhibited the highest relative abundance of Olsenella, while group Y showed a significant increase in unclassified_f Lachnospiraceae compared to the other groups. Bacterial function prediction indicated that pathways related to energy metabolism were more prevalent in group X and Y. This study preliminarily confirms the feasibility of using DPF as feed additives, providing a foundation for further research and evaluation of DPF's application in animal production.

Evaluating Enterococcus faecium9 N-2 as a probiotic candidate from traditional village white cheese

In this study, various functional and probiotic attributes of the Enterococcus faecium 9 N-2 strain isolated from village-style white cheese were characterized, while also assessing its safety. To achieve this, we conducted an in vitro analysis of several key probiotic properties exhibited by the 9 N-2 strain. Notably, this strain demonstrated robust resilience to low pH, high bile salt concentrations, lysozyme, pepsin, pancreatin, and phenol. Furthermore, this strain displayed exceptional auto-aggregation capabilities and moderate co-aggregation tendencies when interacting with Escherichia coli. The cell-free supernatant derived from strain 9 N-2 exhibited significant antimicrobial activity against the tested pathogens. The strain exhibited resistance to gentamicin, meropenem, and bacitracin, while remaining susceptible to vancomycin and various other antibiotics. Furthermore, it was found that E. faecium 9 N-2 possessed the capacity to produce the phytase enzyme. When all the results of this study are evaluated, it is thought that 9 N-2 strain has superior probiotic properties, and therefore it can be used as probiotic in food, medicine, and animal feed in the future. In addition, further in vivo tests should be performed to fully understand its effects and mechanisms of action and to confirm its safety and probiotic effects. Further research and clinical trials are also needed to identify new strains with potential probiotic properties.

The larvicidal effect of the supernatant of Lactobacillus acidophilus ATCC 4356 on Toxocara canis

Human toxocariasis is a parasitic anthropozoonosis that is difficult to treat and control. A previous study carried out with Lactobacillus acidophilus ATCC 4356 revealed that the cell free supernatant (CFS) of this probiotic killed 100% of Toxocara canis larvae in vitro. The present study aimed to investigate the characteristics of the CFS of L. acidophilus ATCC 4356, which may be involved in its larvicidal effects on T. canis. L. acidophilus ATCC 4356 was cultured, and lactic and acetic acids present in the CFS were quantified by high performance liquid chromatography (HPLC). The levels of pH and H2O2 were also analyzed. To assess the larvicidal effect of the CFS, this was tested pure and diluted (1:2 to 1:128) on T. canis larvae. High concentrations of lactic and acetic acids were detected in the CFS. The acidity of the pure CFS was observed at pH 3.8, remaining acidic at dilutions of 1:2 to 1:16. Regarding the in vitro larvicidal effect, 100% death of T. canis larvae was observed using the pure CFS and 1:2 dilution. Based on these results, it can be inferred that the presence of higher concentrations of organic acids and low pH of the medium contributed to the larvicidal activity of the CFS of L. acidophilus ATCC 4356. In addition, the maintenance of the larvicidal effect, even after dilution, suggests a greater chance of the larvicidal effect of this CFS against T. canis in vivo.

Effects of Isaria cicadae on growth, gut microbiota, and metabolome of Larimichthys crocea

The large yellow croaker (Larimichthys crocea) is the most productive mariculture fish in China, and its aquaculture scale is expanding along the southeastern coast of China, but that development is causing environmental damage by increasing the use of antibiotics and other chemicals. How to improve fish immunity through non-antibiotic substances is still a problem facing aquaculture industry. At present, the experiments have shown that Isaria cicadae spent substrate (IC) can improve the growth performance and immunity of Oreochromis niloticus. Therefore, I. cicadae may be a natural alternative to antibiotic for aquaculture. In order to study the effects of IC on growth performance, serum biochemical indices, intestinal microbiota, and intestinal metabolism of large yellow croakers, the fish were divided into three groups with three replicates in each group. Basal diet, basal diet with 2% and 6% IC supplementation (IC2 and IC6 groups), respectively. The results showed that weight gain rate (WG) and specific growth rate (SGR) of large yellow croaker significantly increased (P < 0.05) in IC6 group. The content of triglyceride (TG), low density lipoprotein cholesterol (LDL-C), total protein (TP) and albumin (ALB) increased significantly (P < 0.05), and total cholesterol (T-CHO) decreased significantly (P < 0.05) in IC2 group. Compared to IC0 group, the activity of malondialdehyde (MDA) , superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) increased significantly (P < 0.05) in IC2 group, the activity of total antioxidant capacity (T-AOC) and GSH-Px increased significantly (P < 0.05) in IC6 group, and the activity of lysozyme (LZM) increased significantly in IC2 and IC6 groups. The addition of IC in the diets significantly increased the diversity of the microbial community in the intestine of large yellow croaker (P < 0.05), significantly improved the relative abundance of Acidobacteriota (P < 0.05) at the phylum level, and reduced the relative abundance of Bacteroidota, Desulfobacterota, and Synergistota (P < 0.05). At the genus level, the relative abundance of Bacteroides, Cetobacterium and Mycoplasma, which are dominant bacteria in fish gut, significantly increased (P < 0.05). The relative abundance of Ruminofilibacter, Desulfomicrobium, DMER64, Syntrophomonas, Hydrogenophaga, and Aminobacterium reduced significantly (P < 0.05). Among them, Ruminofilibacter, DMER64, Syntrophomonas and Hydrogenophaga are bacteria that can participate in the hydrolysis and acidification of organic matter, while DMER64 is the hydrogen carrier. The intestinal metabolome analysis showed that IC could improve metabolic composition and function, which was related to host immunity and metabolism. In conclusion, I. cicadae can improve the growth performance, regulate the lipid metabolism and immune and antioxidant capacity of large yellow croakers by regulating intestinal microbiota and intestinal metabolism. This study provides a reference for the application of IC in aquaculture.

Anti-Quorum Sensing Activity of Probiotics: The Mechanism and Role in Food and Gut Health

Background: Quorum sensing (QS) is a cell-to-cell communication mechanism that occurs between inter- and intra-bacterial species and is regulated by signaling molecules called autoinducers (AIs). It has been suggested that probiotics can exert a QS inhibitory effect through their metabolites. Purpose: To provide an overview of (1) the anti-QS activity of probiotics and its mechanism against foodborne pathogenic and spoilage bacteria; (2) the potential role of the QS of probiotics in gut health; and (3) the impact of microencapsulation on QS. Results: Lactobacillus species have been extensively studied for their anti-QS activity and have been found to effectively disrupt QS in vitro. However, their effectiveness in a food matrix is yet to be determined as they interfere with the AI receptor or its synthesis. QS plays an important role in both the biofilm formation of probiotics and pathogenic bacteria. Moreover, in vitro and animal studies have shown that QS molecules can modulate cytokine responses and gut dysbiosis and maintain intestinal barrier function. In this scenario, microencapsulation was found to enhance AI activity. However, its impact on the anti-QS activity of probiotics and its underlying mechanism remains unclear. Conclusions: Probiotics are potential candidates to block QS activity in foodborne pathogenic and food spoilage bacteria. Microencapsulation increases QS efficacy. However, more research is still needed for the identification of the QS inhibitory metabolites from probiotics and for the elucidation of the anti-QS mechanism of probiotics (microcapsules and free cells) in food and the human gut.