We investigated the efficacy of a single bacterium strain, Bacillus subtilis (B. subtilis) YW1, on the performance, morphology, cecal microbiota, and intestinal barrier function of laying hens. A total of 216 28-week-old Hy-line Brown laying hens were divided into three dietary treatment groups, with six replicates of 12 birds each for 4 weeks. The control group (Ctr) was fed a basal diet and the treatment groups, T1 and T2, were fed a basal diet supplemented with B. subtilis at a dose rate of 5 × 10⁸ CFU/kg and 2.5 × 10⁹ CFU/kg, respectively. Dietary supplementation with B. subtilis did not significantly affect overall egg production in both groups, with no obvious changes in average egg weight and intestine morphology. B. subtilis administration also improved the physical barrier function of the intestine by inducing significantly greater expression levels of the tight junction protein occludin in T1 (p = 0.07) and T2 (p < 0.05). Further, supplementation with B. subtilis effectively modulated the cecal microbiota, increasing the relative level of beneficial bacteria at the genus level (e.g., Bifidobacterium p < 0.05, Lactobacillus p = 0.298, Bacillus p = 0.550) and decreasing the level of potential pathogens (e.g., Fusobacterium p < 0.05, Staphylococcus p < 0.05, Campylobacter p = 0.298). Overall, B. subtilis YW1 supplementation cannot significantly improve the egg production; however, it modulated the cecal microbiota towards a healthier pattern and promoted the mRNA expression of the tight junction protein occludin in laying hens, making B. subtilis YW1 a good probiotic candidate for application in the poultry industry, and further expanding the resources of strains of animal probiotics.

Aim Evaluation of probiotic potential of Lactobacillus plantarum (L. plantarum) strain RW1 isolated from healthy dog for its further utilization as dietary supplement in dogs feeding Methods and Results The present study was aimed to evaluate the probiotic potential of L. plantarum strain RW1 (strain RW1) isolated from canine faeces. After confirming by conventional and then 16SrRNA sequencing, the identified strain RW1 was in vitro screened for its survivability in simulated gastrointestinal conditions, low pH, bile salts and adhesion to gut epithelial tissues, growth inhibitory effects on common pathogens and anti-inflammatory potential by measuring mRNA expression level of IL-6, IL-8, IL-1ꞵ in Salmonella infected MODE-K cells. Further, the effects on epithelial barrier function and host defensin peptide (beta-defensin 3) was checked by measuring mRNA expression level of tight junction protein (occludin) and beta-defensin 3 in MODE-K cells. The strain RW1 showed considerable potential to survive in simulated gastrointestinal environmental conditions, low pH, high bile salt concentrations along with good adhesion properties with MODE-K cell line. Pathogenic bacterial growth and their adhesion to MODE-K cell line was significantly inhibited by strain RW1. Real-time PCR analyses demonstrated that the strain RW1 inhibited Salmonella induced pro-inflammatory cytokines (IL-6, IL-8, IL-1ꞵ) production and reinforce expression of tight junction protein (occludin). The strain RW1 did not induce mRNA expression of beta-defensin 3. Conclusion Based on in vitro results the strain RW1 has potential to be used as a probiotic supplement in dogs feeding. However further study involving in vivo health effects is needed. Significance and impact of study Antibiotics have many side effects and nowadays the probiotics are considered potential antibiotics alternatives. This study evaluates the probiotic potential of dog isolated L. plantarum strain RW1 to use it as a dietary supplement in dogs feeding to control infectious diseases.

Mycoplasma bovis (M. bovis) is characterized by a reduced genomic size and limited synthetic capacity, including the inability to synthesize nucleotides de novo, relies on nucleases for nutrient acquisition and survival. A number of nucleases have been implicated in M. bovis pathogenicity, facilitating substrate degradation and contributing to DNA repair mechanisms that enhance bacterial persistence. The present study confirmed that the T5.808 mutant, in which a novel nuclease gene (Mbov_0701) was disrupted by the mini-Tn4001 transposon, exhibits a growth defect when co-cultured with EBL cells. However, the restoration of Mbov_0701 resulted in the resumption of growth in the mutant. The characterization of MbovP701 revealed that it had high activity in hydrolyzing dsDNA with 5′- to 3′- polarity. Furthermore, the substrates of MbovP701 were extended to include linear dsDNA, ssDNA, RNA, and plasmid DNA. The exonuclease activity is dependent on the presence of Mn²⁺ and/or Mg²⁺ ions, with an optimal pH and temperature of 8.3 and 43 °C, respectively. The truncation experiments of rMbovP701 revealed that YqaJ (41–185 aa) is the key functional domain of MbovP701 exonuclease. In conclusion, the present study identified a novel nuclease in M. bovis that plays an essential role in the proliferation of this minimal organism. This finding elucidates the survival strategy and pathogenesis of M. bovis, suggesting a potential therapeutic strategy for the treatment of M. bovis through targeting the inhibition of MbovP701. Moreover, it provides a foundation for future investigations into the interactions between MbovP701 and other nucleases involved in M. bovis biology.

Treatment of common pathogens, such as Salmonella species, Escherichia coli, Staphylococcus aureus, etc., is a big challenge for a practitioner. Antibiotics’ side effects during their application for the treatment of infectious diseases should not be underestimated as they have many issues, such as the transfer of antibiotics-resistant genes, dysbiosis, and antibiotic-resistant strains, which is the main hurdle in the eradication of diseases. To avoid these antibiotics complications, in modern countries, the interest of using probiotics in feed supplementation to promote health and prevent or treat intestinal infectious diseases has been increasing. The purpose of the present study was to evaluate the probiotic potential of three Lactobacilli strains isolated from clinically healthy dogs for their further utilization as a dietary supplement for dogs to avoid pathogenic and antibiotic complication. After 16SrRNA sequencing, in vitro tests were conducted to assess the survival potential of Lactobacilli under simulated gastrointestinal conditions and adhesion ability to the MODE-K cell line, effects on epithelial barrier function, anti-inflammatory activities, effects on host defensin peptides (beta-defensin 3), and inhibitory effects on common pathogens. Lactobacilli showed considerable potential to survive in simulated gastrointestinal environmental conditions, low pH, and high bile salt concentrations along with good adhesion properties with MODE-K cells. Pathogenic bacterial growth and their adhesion to MODE-K cells were significantly inhibited by Lactobacilli. Real-time PCR analyses further demonstrated that the L. acidophilus strain AR1 and AR3 inhibit Salmonella-induced proinflammatory cytokine (IL-6, IL-8, IL-1β) production and reinforce the expression of tight junction protein (occludin). None of the strains induce mRNA expression of beta-defensin 3 in MODE-K cells. Based on the in vitro results, the L. acidophilus strain AR1 has the potential to be supplemented in canine feed. However, further in vivo studies investigating health-promoting effects are awaited.

Antibiotics are commonly used to treat infectious diseases. However, massive and inappropriate antibiotics usage cause many problems including the emergence and spread of antibiotic-resistant bacteria. To avoid this issue, in modern countries the interest of using probiotics in feed supplementation to promote health and prevent or treat intestinal infectious diseases in companion animals like dogs has been increasing. We evaluate the probiotic potential of Lactobacilli isolated from healthy dogs faeces. The isolated Lactobacilli were first confirmed by 16SrRNA sequencing, then in vitro tests were conducted to assess survival potential of Lactobacilli under simulated gastrointestinal conditions and adhesion ability to gut epithelia, effects on epithelial barrier function, anti-inflammatory activities, effects on defensin peptides (beta-defensin 3) and inhibitory effects on common pathogens. Lactobacilli showed considerable potential to survive in simulated gastrointestinal environmental conditions, low pH, high bile salt concentrations along with good adhesion properties with MODE-K cells. Pathogenic bacterial growth and their adhesion to MODE-K cells was significantly inhibited by Lactobacilli. Real-time PCR analyses further demonstrated that L. acidophilus strain AR1 and AR3 inhibit Salmonella-induced proinflammatory cytokines (IL-6, IL-8, 1ꞵ) production and reinforce expression of tight junction protein (occludin). None of the strain induce mRNA expression of beta-defensin 3 in MODE-K cells. Based on in vitro results the L. acidophilus strain AR1 has potential to be supplemented in canine feed. However, further in vivo studies investigating health-promoting effects are awaited.