Antibacterial activity of Lactobacillus plantarum isolated from Tibetan yaks

Characterization and Assessment of Native Lactic Acid Bacteria from Broiler Intestines for Potential Probiotic Properties

Probiotics are the most promising alternative to antibiotics for improving animal production and controlling pathogenic infections, while strains derived from natural hosts are considered highly desirable due to their good adaptation to the gastrointestinal tract. The aim of this study was to screen Lactobacillus with broad-spectrum antibacterial activity from broilers fed an antibiotic-free diet and evaluate their potential as poultry probiotics. A total of 44 lactic acid bacteria (LAB) strains were isolated from the intestines of healthy broilers, among which 3 strains exhibited outstanding antimicrobial activity and were subsequently identified through 16S rRNA sequencing as Enterococcus faecium L8, Lactiplantibacillus plantarum L10, and Limosilactobacillus reuteri H11. These three isolates demonstrated potent bacteriostatic activity against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella cholerae, with inhibition zones ranging from 15.67 ± 1.53 to 21.33 ± 0.58 mm. The selected LAB strains exhibited high tolerance to acid and bile salts, with L. reuteri H11 displaying the highest survival rate (ranging from 34.68% to 110.28%) after exposure to 0.3% (w/v) bile salts for 6 h or a low pH environment (pH 2, 2.5, and 3) for 3 h. Notably, L. reuteri H11 outperformed other strains in terms of hydrophobicity (84.31%), auto-aggregation (53.12%), and co-aggregation with E. coli ATCC 25922 (36.81%) and S. aureus ATCC 6538 (40.20%). In addition, the three LAB isolates were either fully or moderately susceptible to the tested antibiotics, except for strain L8, which resisted gentamycin and vancomycin. Consequently, these three LAB strains, especially L. reuteri H11, isolated from the intestines of broiler chickens, represent promising probiotic candidates that can be employed as feed additives to enhance production performance and control poultry pathogens.

Microencapsulate Probiotics (MP) Promote Growth Performance and Inhibit Inflammatory Response in Broilers Challenged with Salmonella typhimurium

Antibiotic-resistant bacteria are prevalent in husbandry around the world due to the abuse of antibiotic growth promoters (AGPs); therefore, it is necessary to find alternatives to AGPs in animal feed. Among all the candidates, probiotics are promising alternatives to AGPs against Salmonella infection. The anti-Salmonella effects of three probiotic strains, namely, Lactobacillus crispatus 7-4, Lactobacillus johnsonii 3-1, and Pediococcus acidilactici 20-1, have been demonstrated in our previous study. In this study, we further obtained the alginate beads containing compound probiotics, namely, microencapsulate probiotics (MP), and evaluated its regulatory effect on the health of broilers. We incubated free and microencapsulate probiotics in simulated gastric and intestinal juice for 2 h, and the results showed that compared to free probiotics, encapsulation increased tolerance of compound probiotics in the simulated gastrointestinal condition. We observed that the application of probiotics, especially MP, conferred protective effects against Salmonella typhimurium (S.Tm) infection in broilers. Compared to the S.Tm group, the MP could promote the growth performance (p < 0.05) and reduce the S.Tm load in intestine and liver (p < 0.05). In detail, MP pretreatment could modulate the cecal microflora and upregulate the relative abundance of Lactobacillus and Enterobacteriaceae. Besides, MP could reduce the inflammation injury of the intestine and liver, reduce the pro-inflammatory cytokines (IL-6, TNF-α, IL-1β) expression, and induce of anti-inflammatory cytokine (IL-10) expression. Furthermore, MP could inhibit NLRP3 pathway in ileum, thereby attenuating S.Tm-induced inflammation. In conclusion, MP could be a new feeding supplementation strategy to substitute AGPs in poultry feeding.

Assessing the probiotic potential, antioxidant, and antibacterial activities of oat and soy milk fermented with Lactiplantibacillus plantarum strains isolated from Tibetan Kefir

Sufficient intake of probiotics has been shown to help in the digestion, protect the body against pathogenic microorganisms and boost the immune system. Recently, due to high prevalence of milk allergies and lactose intolerance in population, the non-dairy based probiotic alternative are becoming increasing popular. In this context, the oat milk and soya milk-based fermented products can be an ideal alternative for the development of Lactic acid bacteria bacteria based probiotics. These bacteria can not only improve the product's flavor and bioavailability but also increases its antibacterial and antioxidant capabilities due to fermentation process. The purpose of the resent work was to assess the antioxidant and probiotic properties of oat and soy milk that had been fermented with three different strains of Lactiplantibacillus plantarum (L. plantarum) including L. plantarum 12-3, L. plantarum K25, and L. plantarum YW11 isolated from Tibetan Kefir. Different validated assays were used to evaluate the probiotic properties, adhesion and survival in the digestive system (stomach, acid and bile salts resistance), antioxidant and antimicrobial activities and safety (ABTS and DPPH scavenging assays) of these strains. Results of the study showed that soya milk and oat milk fermented with L. plantarum strains possess promising probiotic, antibacterial and antioxidant properties. These results can be helpful to produce dairy-free probiotic replacements, which are beneficial for those who are unable to consume dairy products due to dietary or allergic restrictions.

Akkermansia muciniphila and Lactobacillus plantarum ameliorate systemic lupus erythematosus by possibly regulating immune response and remodeling gut microbiota

Systemic lupus erythematosus (SLE), characterized by persistent inflammation, is a complex autoimmune disorder that affects all organs, challenging clinical treatment. Dysbiosis of gut microbiota promotes autoimmune disorders that damage extraintestinal organs. Modulating the gut microbiome is proposed as a promising approach for fine-running parts of the immune system, relieving systematic inflammation in multiple diseases. This study demonstrated that the administration of Akkermansia muciniphila and Lactobacillus plantarum contributed to an anti-inflammatory environment by decreasing IL-6 and IL-17 and increasing IL-10 levels in the circulation. The treatment of A. muciniphila and L. plantarum restored the intestinal barrier integrity to a different extent. In addition, both strains reduced the deposit of IgG in the kidney and improved renal function significantly. Further studies revealed distinct remodeling roles of A. muciniphila and L. plantarum administration on the gut microbiome. This work demonstrated essential mechanisms of how A. muciniphila and L. plantarum remodel gut microbiota and regulate the immune responses in the SLE mice model. IMPORTANCE Several pieces of research have demonstrated that certain probiotic strains contribute to regulating excessive inflammation and restoring tolerances in the SLE animal model. More animal trials combined with clinical studies are urgently needed to further elucidate the mechanisms for the effect of specific probiotic bacteria in preventing SLE symptoms and developing novel therapeutic targets. In this study, we explored the role of A. muciniphila and L. plantarum in ameliorating the SLE disease activity. Both A. muciniphila and L. plantarum treatment relieved the systemic inflammation and improved renal function in the SLE mouse model. We demonstrated that A. muciniphila and L. plantarum contributed to an anti-inflammatory environment by regulating cytokine levels in the circulation, restoring the intestinal barrier integrity, and remodeling the gut microbiome, however, to a different extent.

Effects of lactic acid bacteria isolated from Tibetan chickens on the growth performance and gut microbiota of broiler

Lactic acid bacteria (LAB) are organic supplements that have several advantages for the health of the host. Tibetan chickens are an ancient breed, which evolve unique gut microbiota due to their adaptation to the hypoxic environment of high altitude. However, knowledge of LAB isolated from Tibetan chickens is very limited. Thus, the purpose of this study was to assess the probiotic properties of Lactobacillus Plantarum (LP1), Weissella criteria (WT1), and Pediococcus pentosaceus (PT2) isolated from Tibetan chickens and investigate their effects on growth performance, immunoregulation and intestinal microbiome in broiler chickens. Growth performance, serum biochemical analysis, real-time PCR, and 16S rRNA sequencing were performed to study the probiotic effects of LP1, WT1, and PT2 in broiler chickens. Results showed that LP1, WT1 and PT2 were excellent inhibitors against Escherichia coli (E. coli ATCC25922), meanwhile, LP1, WT1, and PT2 significantly increased weekly weight gain, villus height, antioxidant ability and gut microbiota diversity indexes in broilers. In addition, LP1 and PT2 increased the relative abundance of Lactobacillus and decreased Desulfovibrio in comparison with T1 (control group). Additionally, oral LAB can reduce cholesterol and regulate the expression of tight junction genes in broiler chickens, suggesting that LAB can improve the integrity of the cecal barrier and immune response. In conclusion, LAB improved the growth performance, gut barrier health, intestinal flora balance and immune protection of broiler chickens. Our findings revealed the uniqueness of LAB isolated from Tibetan chickens and its potential as a probiotic additive in poultry field.

Functional Characterization of Lactobacillus plantarum Isolated from Cow Milk and the Development of Fermented Coconut and Carrot Juice Mixed Beverage

Screening probiotics are crucial for assessing their safety, security, and further production of functional foods for human health. The present study aimed to isolate and identify bacteria from raw cow's milk samples that exhibit health benefits upon consumption. We characterized the probiotic properties of Lactobacillus plantarum (also called Lactiplantibacillus plantarum) strains CMGC2 and CMJC7 isolated from cow milk by in vitro study. The strains exhibited tolerance to simulated gastric conditions and were further identified by 16S rRNA sequencing as Lactobacillus plantarum (L. plantarum) CMGC2 and CMJC7. Both isolates were evaluated in vitro for their probiotic attributes, viz. hydrophobicity, autoaggregation, co-aggregation, lysozyme tolerance, antibacterial activity, antibiotic susceptibility, hemolytic activity, and phenol tolerance. The isolates CMGC2 and CMJC7 showed excellent probiotic attributes; hence, both strains were selected to produce coconut and carrot juice mixed beverages (CCMB). The CCMB was evaluated for the pH, acid-production rate, and total viable bacterial counts. The results showed that the CCMB was an excellent medium for the growth of CMGC2 and CMJC7 as it supported adequate growth of organisms (8.93 CFU/mL and 8.68 CFU/mL, respectively) even after 48 h of incubation. In conclusion, CMGC2 and CMJC7 can be used to develop different beverages possessing nutritive and probiotic values, and these beverages can be used for producing unique products.

Complete genome analysis of Bacillus subtilis derived from yaks and its probiotic characteristics

Probiotics have attracted attention due to their multiple health benefits to the host. Yaks inhabiting the Tibetan plateau exhibit excellent disease resistance and tolerance, which may be associated with their inner probiotics. Currently, research on probiotics mainly focuses on their positive effects on the host, but information regarding their genome remains unclear. To reveal the potential functional genes of Bacillus subtilis isolated from yaks, we sequenced its whole genome. Results indicated that the genomic length of Bacillus subtilis was 866,044,638 bp, with 4,429 coding genes. The genome of this bacteria was composed of one chromosome and one plasmid with lengths of 4,214,774 and 54,527 bp, respectively. Moreover, Bacillus subtilis contained 86 tRNAs, 27 rRNAs (9 16S_rRNA, 9 23S_rRNA, and 9 5S_rRNA), and 114 other ncRNA. KEGG annotation indicated that most genes in Bacillus subtilis were associated with biosynthesis of amino acids, carbon metabolism, purine metabolism, pyrimidine metabolism, and ABC transporters. GO annotation demonstrated that most genes in Bacillus subtilis were related to nucleic acid binding transcription factor activity, transporter activity, antioxidant activity, and biological adhesion. EggNOG uncovered that most genes in Bacillus subtilis were related to energy production and conversion, amino acid transport and metabolism, carbohydrate transport and metabolism. CAZy annotation found glycoside hydrolases (33.65%), glycosyl transferases (22.11%), polysaccharide lyases (3.84%), carbohydrate esterases (14.42%), auxiliary activities (3.36%), and carbohydrate-binding modules (22.59%). In conclusion, this study investigated the genome and genetic properties of Bacillus subtilis derived from yaks, which contributed to understanding the potential prebiotic mechanism of probiotics from the genetic perspective.

Assessments of Probiotic Potentials of Lactiplantibacillus plantarum Strains Isolated From Chinese Traditional Fermented Food: Phenotypic and Genomic Analysis

The lack of rapid and effective approaches to determine the health benefits of strains is one of the main challenges affecting the selection of probiotics from large numbers of candidates. In this study, the probiotic potential of 44 Lactiplantibacillus plantarum strains isolated from different Chinese traditional fermented foods was evaluated, including acid and bile salt resistance, adhesion ability, survival in simulated human gastrointestinal transit, antioxidant activity, bile salt hydrolase (BSH) activity, and antibacterial activity. All tested L. plantarum strains showed high antioxidant capacity, BSH activity, and antibacterial activity. Among the strains, B652, C232, D444, and E932 were identified as the best comprehensive performed strains, which were selected for whole-genome sequencing, in order to provide clear information and identify key genes responsible for functional characteristics in vitro. It demonstrated that the antioxidant activity, adhesion activity, and ability to survive in the simulated gastric environment were found to be closely correlated with antioxidant enzyme encoding genes, cell-surface protein-encoding genes, and stress response genes, respectively. The numbers of functional genes present in strains might decide their performance in probiotic profile evaluation. The outcome of the study could support the development of a novel approach for the screening and identification of probiotics.

The Impacts of Lactiplantibacillus plantarum on the Functional Properties of Fermented Foods: A Review of Current Knowledge

One of the most varied species of lactic acid bacteria is Lactiplantibacillus plantarum (Lb. plantarum), formerly known as Lactobacillus plantarum. It is one of the most common species of bacteria found in foods, probiotics, dairy products, and beverages. Studies related to genomic mapping and gene locations of Lb. plantarum have shown the novel findings of its new strains along with their non-pathogenic or non-antibiotic resistance genes. Safe strains obtained with new technologies are a pioneer in the development of new probiotics and starter cultures for the food industry. However, the safety of Lb. plantarum strains and their bacteriocins should also be confirmed with in vivo studies before being employed as food additives. Many of the Lb. plantarum strains and their bacteriocins are generally safe in terms of antibiotic resistance genes. Thus, they provide a great opportunity for improving the nutritional composition, shelf life, antioxidant activity, flavour properties and antimicrobial activities in the food industry. Moreover, since some Lb. plantarum strains have the ability to reduce undesirable compounds such as aflatoxins, they have potential use in maintaining food safety and preventing food spoilage. This review emphasizes the impacts of Lb. plantarum strains on fermented foods, along with novel approaches to their genomic mapping and safety aspects.

Synthesis of silver nanoparticles with high efficiency and stability by culture supernatant of Bacillus ROM6 isolated from Zarshouran gold mine and evaluating its antibacterial effects

Background

The use of bacteria to synthesize nanoparticles as an environment-friendly method has recently been considered by researchers. Bacteria residing in different mines have shown high potential in the synthesis of metal nanoparticles due to their compatibility with the environment. The aim of this study was to evaluate the ability of Zarshouran gold mine bacteria to synthesize silver nanoparticles and their antibacterial activity.

Methods

After isolation of mine bacteria and several screening steps, silver ion tolerant bacteria that were able to synthesize extracellular silver nanoparticles were isolated and the most suitable isolate was selected and sequenced. The characteristics, stability, and production efficiency of silver nanoparticles were evaluated using UV–vis spectrophotometry, DLS, TEM, FTIR, and X-ray diffraction analysis. Finally, the antibacterial effect of silver nanoparticles against pathogenic bacteria was investigated.

Results

Among the eight silver-tolerant bacteria, isolate No. 6 had high antibacterial activity and high potential in the synthesis and stabilization of silver nanoparticles. Therefore, this isolate was selected for the next experiments. The results of 16S rDNA sequencing showed that this isolate is related to Bacillus pumilus. We registered in the NCBI Bank called ROM6 with access number MW440543. The DLS and TEM analysis showed that silver nanoparticles produced by this isolate were most spherical with a size of less than 25 nm and were stable for at least 180 days. The efficiency at concentrations less than 0.9 g/l silver nitrate was over 90% and the minimum inhibition concentration of nanoparticles was determined against S. aureus, E. coli, P. aeruginosa, and A. baumannii ranging from 1.4 to 5.6 µg/ml.

Conclusion

We found that the bacteria residing in the gold mine have a high capacity for the synthesis of spherical and high stable silver nanoparticles with a strong antibacterial effect.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02490-5.

Characterization of a Lactiplantibacillus plantarum R23 Isolated from Arugula by Whole-Genome Sequencing and Its Bacteriocin Production Ability

Lactiplantibacillus plantarum is one of the lactic acid bacteria species most used as probiotics and starter cultures in food production. Bacteriocin-producers Lpb. plantarum are also promising natural food preservatives. This study aimed to characterize Lpb. plantarum R23 and its bacteriocins (R23 bacteriocins). The genome sequence of Lpb. plantarum R23 was obtained by whole-genome sequencing (WGS) in an Illumina NovaSeq platform. The activity of Lpb. plantarum R23-produced bacteriocin against two Listeria monocytogenes strains (L7946 and L7947) was evaluated, and its molecular size was determined by tricine-SDS-PAGE. No virulence or antibiotic resistance genes were detected. Four 100% identical proteins to the class II bacteriocins (Plantaricin E, Plantaricin F, Pediocin PA-1 (Pediocin AcH), and Coagulin A) were found by WGS analysis. The small (<6.5 kDa) R23 bacteriocins were stable at different pH values (ranging from 2 to 8), temperatures (between 4 and 100 °C), detergents (all, except Triton X-100 and Triton X-114 at 0.01 g/mL), and enzymes (catalase and α-amylase), did not adsorb to the producer cells, had a bacteriostatic mode of action and their maximum activity (AU/mL = 12,800) against two L. monocytogenes strains occurred between 15 and 21 h of Lpb. plantarum R23 growth. Lactiplantibacillus plantarum R23 showed to be a promising bio-preservative culture because, besides being safe, it produces a stable bacteriocin or bacteriocins (harbors genes encoding for the production of four) inhibiting pathogens as L. monocytogenes. Further studies in different food matrices are required to confirm this hypothesis and its suitability as a future starter culture.

Probiotics and Amelioration of Rheumatoid Arthritis: Significant Roles of Lactobacillus casei and Lactobacillus acidophilus

Rheumatoid arthritis is a chronic autoimmune disorder that can lead to disability conditions with swollen joints, pain, stiffness, cartilage degradation, and osteoporosis. Genetic, epigenetic, sex-specific factors, smoking, air pollution, food, oral hygiene, periodontitis, Prevotella, and imbalance in the gastrointestinal microbiota are possible sources of the initiation or progression of rheumatoid arthritis, although the detailed mechanisms still need to be elucidated. Probiotics containing Lactobacillus spp. are commonly used as alleviating agents or food supplements to manage diarrhea, dysentery, develop immunity, and maintain general health. The mechanism of action of Lactobacillus spp. against rheumatoid arthritis is still not clearly known to date. In this narrative review, we recapitulate the findings of recent studies to understand the overall pathogenesis of rheumatoid arthritis and the roles of probiotics, particularly L. casei or L. acidophilus, in the management of rheumatoid arthritis in clinical and preclinical studies.

Probiotic potential and anticancer properties of Pediococcus sp. isolated from traditional dairy products

Herein, 18 lactic acid bacteria isolated from 30 samples of traditional dairy products were identified, and their probiotic potential was evaluated. According to the results, almost all strains showed the probiotic properties sufficiently, though M1 had better characterise. 16S rRNA gene sequencing revealed that this strain belongs to the Pediococcus sp. (<95 % similarity). This strain had substantial antipathogenic activity and did not show any worrying antibiotic resistance. Also, the strain was resistant to high concentrations of bile salt (1 %), NaCl (6.5 %), and low pH (2). Furthermore, it was revealed that cell-free supernatant (CFS), heat-killed cells and live cells derived from M1 significantly decreased the viability of MCF-7 cells so that the CFS resulted in 85 % cell death. Flow cytometry and western blot analysis determined that this compound induced apoptosis in the cancerous cells through increasing the BAX protein expression and decreasing the Bcl-2 protein expression.

Isolation and Evaluation of Probiotic Potential of Lactic Acid Strains From Healthy Equines for Potential Use in Salmonella Infection

The objective of the present study was to evaluate the probiotic properties, security and antibacterial ability in vivo of isolated strains from healthy equine. In the present study, two Pediococcus acidilactici (P1 and P2) and two Lactobacillus equi (L1 and L2) were isolated. All isolates were died when exposed to pH 2.0 for 3 hours but survived at pH 3.0 and pH 4.0 with differential survival rate, and there is a higher survival rate at pH 4.0. Similarly, the isolates showed different tolerance to bile. The viable bacteria count was sustained at high levels in a tolerance test with artificial gastrointestinal fluid. The isolates survived and grew at temperatures between 37 and 55°C but died at 65°C. Four strains exhibited inhibitory activity against pathogens, including Salmonella typhimurium (CVCC542), Escherichia coli (C83902), Staphylococcus aureus (BNCC186335), and Pasteurella multocida (clinical isolate). These isolates exhibited differential antibiotic susceptibility. In safety trials, all isolates were γ-hemolytic, and the oral toxicity of strains P1 (gavaged with 1 × 109 CFU/day) and L1 (gavaged with 1 × 109 CFU/day) were analyzed in mice. There were no effects on the overall health status of mice. There were no prominent differences in the incidence of bacteria translocation to blood, liver, and spleen. Mice gavaged with Pediococcus acidilactici P1 (1 × 108 CFU/day) or Lactobacillus equi L1 (1 × 108 CFU/day) as prevention showed lower rates of diarrhea and mortality after being challenged with Salmonella typhimurium (4 × 106 CFU signal dose, 0.1 mL by intragastric gavage). The results indicate that the isolated strains could act as potential probiotics, providing a new way to reduce salmonella infection, which merit future application studies.

Probiotic and Antioxidant Potential of Lactobacillus reuteriLR12 and Lactobacillus lactisLL10 Isolated from Pineapple Puree and Quality Analysis of Pineapple-Flavored Goat Milk Yoghurt during Storage

In recent years, studies have focused on the therapeutic properties of probiotics to eliminate pathogenic microorganisms associated with various diseases. Lactobacilli are important probiotics groups that have been found to possess many health-promoting activities. This study was carried out to isolate LactobacillusreuteriLR12 and L. lactisLL10 from pineapple puree. The invitro analysis to evaluate probiotic characteristics of the isolated bacteria included survival in bile and acid tolerance. The cell-free supernatant of L. reuteri LR12 was effective against various pathogenic bacteria and fungi compared with L. lactisLL10. These two bacterial strains have strong anti-biofilm activity (100%) against Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus. The bacterial strains exhibited adhesion properties to HT-29 cells (human colorectal adenocarcinoma). These bacteria showed DPPH- (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free radical scavenging activity, scavenging of hydroxyl radical activity, superoxide radical scavenging activity, and reducing power activity in the range of 72% ± 3%to 89.3% ± 1.7%, 64% ± 2.7%to 66.8% ± 1.5%, 59.8% ± 4.1% to 63.8% ± 2.1%, and 60.4% ± 1.8%to 66.1% ± 3.3%, respectively. Pineapple puree was used as the starter culture with milk for 2 days for yogurt preparation. Pineapple puree increased flavor and showed the physicochemical properties of yogurt. The finding of the sensory evaluation revealed no significant change compared with the control, except the appearance of yogurt. These findings show that Lactobacilli and pineapple puree have potential use in various probiotic preparations for the fermentation industry.

Antibacterial Activity of Lactobacillus Strains Isolated from Mongolian Yogurt against Gardnerella vaginalis

Worldwide interest in the use of functional foods containing probiotic bacteria such as Lactobacillus and Bifidobacterium for health promotion and disease prevention has increased significantly. Probiotics have demonstrated beneficial properties including strengthening the body's natural defense system, inhibiting the growth of pathogenic bacteria, and regulating mental activity, but their effects on the human vagina have not been fully elucidated. The primary purpose of our study was to isolate Lactobacillus strains from old yogurt, a traditional dairy product, and investigate their probiotic potential with respect to the human vaginal system. Four Lactobacillus plantarum (L. plantarum) strains, named ZX1, ZX2, ZX27, and ZX69, were isolated from the yogurt samples. Simultaneously, we used a commercial Lactobacillus strain (Lactobacillus delbrueckii DM8909) as a control strain. We tested the antimicrobial activity of Lactobacillus isolates against Escherichia coli and Gardnerella vaginalis by agar spot and well diffusion tests. Then, we tested the antibiotic susceptibility of the 5 strains by using the minimal inhibitory concentration method. We attempted to detect possible bacteriocin genes by PCR sequencing technique. Using a chemically defined medium simulating genital tract secretions, we found that the selected Lactobacillus strains could alter the expression of known virulence genes in Gardnerella vaginalis. Bacteriocins derived from these isolated strains had potent antibacterial activity against G. vaginalis and E. coli, with the most effective activity observed in the case of ZX27. In addition, all strains including the L. delbrueckii DM8909 were positive for the presence of the plantaricin cluster of genes described in L. plantarum C11. The tested stains possessed the pln gene indicating that one of the antibacterial agents was plantaricin. We assume that the production of antimicrobial substances such as bacteriocins induce G. vaginalis to upregulate antimicrobial resistance genes. The new isolated strains have bacteriocin-related genes and can change the antimicrobial resistance gene transcription of G. vaginalis.

Probiotic potential of Lactobacillus on the intestinal microflora against Escherichia coli induced mice model through high-throughput sequencing

The aim of this study was to evaluate the antibacterial potential of Lactobacillus screened from Tibetan yaks on clinical symptoms and intestinal microflora in enteroinvasive Escherichia coli (EIEC) induced mice model. In vitro study, Lactobacillus reuteri (LR1) exhibited stronger resistance to acid and bile and inhibited the growth of EIEC than Lactobacillus mucosae (LM1). The mice were randomly divided into four groups i.e. the LR1 group (LR1 1 × 10⁹ CFU/day), LM1 group (LM1 1 × 10⁹ CFU/day), blank control group and control group. Mice in control, LR1, and LM1 groups were challenged with EIEC on day 23. The body weight in the control and LM1 groups were significantly decreased after the infection with EIEC (P < 0.05), whereas the body weight of mice in the LR1 group did not change significantly (P > 0.05). The lowest diarrhea rate was recorded in the LR1 group after infection with EIEC. The results showed that the number of pathogens in the control group was higher than that in the experimental groups. The sequence analysis and OTU classification showed that the duodenum, ileum, and cecum of mice in the LR1 group had the highest number of OTUs compared with other groups. Whereas, the diversity analysis showed that in duodenum, ileum and cecum of mice in the LR1 group had the highest abundance and diversity. The composition of intestinal microbes indicated the presence of high proportions of Firmicutes, Proteobacteria and Bacteroidetes. Heat map analysis indicated high abundance of Bdello vibrio in the duodenum of mice in the LR1 group, while many pathogens were found in the different part of intestines in the control group, such as Streptococcus, Clostridium and Pseudomonas. In conclusion, pre-supplementation of LR1 alleviate the clinical symptoms caused by E. coli, and promote a healthy gut flora.

Probiotic and Triticale Silage Fermentation Potential of Pediococcus pentosaceus and Lactobacillus brevis and Their Impacts on Pathogenic Bacteria

The purpose of this study was to identify potent lactic acid bacteria that could have a great impact on triticale silage fermentation at different moisture levels and determine their anti-bacterial activity and high probiotic potential. For this purpose, Pediococcus pentosaceus (TC48) and Lactobacillus brevis (TC50) were isolated from fermented triticale silage. The fermentation ability of these isolates in triticale powder was studied by an ensiling method. TC48 had higher ability to ferment silage powder by increasing the lactic acid content of silage than TC50. Extracellular supernatant (ECS) of TC48 and TC50 exhibited strong antibacterial effects (inhibition zone diameters: 18-28 mm) against tested cattle pathogenic bacteria with minimum inhibitory/ minimum bactericidal concentrations (MIC/MBC) values of 5.0-10 mg/mL and 10-20 mg/mL, respectively. Extracellular supernatant (ECS) of TC48 and TC50 showed antibacterial activities on E. coli, P. aeruoginosa, S. aureus and E. faecalis through destruction of membrane integrity as confirmed by decreased viability, and increased 260 nm absorbing material in culture filtrate of pathogenic bacteria exposed to ECS of both strains. TC48 and TC50 strains exhibited high tolerance to artificial gastric, duodenal and intestinal fluids. TC48 showed good hydrophobicity and auto-aggregations properties. TC48 and TC50 significantly co-aggregated with E. coli, P. aeruoginosa, S. aureus and E. faecalis in a time-dependent manner. In summary, all of the bacteria had a positive impact on at least one functional property of the silage during the fermentation process. However, the addition of P. pentosaceus (TC48) and L. brevis (TC50) yielded the greatest silage quality improvement, having high antibacterial and probiotic properties.

Molecular Characterization and Heterologous Production of the Bacteriocin Peocin, a DNA Starvation/Stationary Phase Protection Protein, from Paenibacillus ehimensis NPUST1

The production of a bacteriocin-like substance with antimicrobial activity, named peocin, by the probiotic Paenibacillus ehimensis NPUST1 was previously reported by our laboratory. The present study aimed to identify peocin and increase the peocin yield by heterologous expression in Escherichia coli BL21(DE3). Peocin was identified as a DNA starvation/stationary phase protection protein, also called DNA-binding protein from starved cells (Dps), by gel overlay and LC-MS/MS analysis. For mass production of peocin, fed-batch cultivation of E. coli was performed using a pH-stat control system. Purification by simple nickel affinity chromatography and dialysis yielded 45.3 mg of purified peocin from a 20-mL fed-batch culture (49.3% recovery). The biological activity of the purified peocin was confirmed by determination of the MIC and MBC against diverse pathogens. Purified peocin exhibited antimicrobial activity against aquatic, food spoilage, clinical and antibiotic-resistant pathogens. In an in vivo challenge test, zebrafish treated with purified peocin exhibited significantly increased survival rates after A. hydrophila challenge. The present study is the first to show the antimicrobial activity of Dps and provides an efficient strategy for production of bioactive peocin, which will aid the development of peocin as a novel antimicrobial agent with potential applications in diverse industries.

Probiotic Potential of Leuconostoc pseudomesenteroides and Lactobacillus Strains Isolated From Yaks

The purpose of this study was to evaluate the antibacterial activity and safety of bacterias with probiotic potential isolated from free-ranging Tibetan yaks in high altitude regions of Tibet. For this purpose, one Leuconostoc pseudomesenteroides strain (named P1) and two Lactobacillus johnsonii and Lactobacillus mucosae strains (named LY1 and LY2), respectively, were isolated from fecal samples of Tibetan yaks. The antibacterial activity of the isolates was studied using Escherichia coli (E. coli ATCC 25922), Staphylococcus aureus (S. aureus ATCC 26112), and Salmonella enteritidis (S. enteritidis NCTC 13349) as indicator pathogens. The results showed that LY1 had high antibacterial efficacy against E. coli and S. enteritidis, while P1 had the most powerful bacteriostatic ability against S. aureus. PCR amplification showed that all the isolated strains were positive for Ent P2 (enterocin P-like bacteriocin) and exhibited a high tolerance to bile and low pH. Moreover, the safety of P1, LY1, and LY2 was determined through antibiotic resistance experiments, resistance gene testing, and hemolytic analysis while the antibacterial activity was assessed by in vitro and in vivo experiments. The LY2 strain was abandoned as a potential probiotic due to the detection of the vanA gene. The mice were fed from days 1 to 30 in six groups, the P1-1 (gavaged with P1 1 × 108 CFU/day), P1-2 (gavaged with P1 1 × 109 CFU/day), LY1-1 (gavaged with LY1 1 × 108 CFU/day), LY1-2 (gavaged with LY1 1 × 109 CFU/day), control (gavaged with an equal volume of vehicle), and blank control (gavaged with an equal volume of vehicle) groups. After 30 days, mice in the P1-1, P1-2, LY1-1, LY1-2, and control groups were intraperitoneal challenged with 1 × 108 CFU of E. coli (n = 10) in the abdomen. After 2 days of infection, the mice in the control group showed more severe damage in the liver, spleen and intestine than the mice in the P1-2 and LY1-2 groups. The mice in the P1-2 and LY1-2 groups had lower rates of diarrhea and mortality than other groups. In conclusion, bacteria with probiotic potential isolated from yaks may possibly be effective and safe antibacterial substances, providing a new treatment method to reduce the incidence of diarrhea associated with bacterial diseases in yaks.

Socio-economic burden of parasitic infections in yaks from 1984 to 2017 on Qinghai Tibetan Plateau of China-A review

Yak is an important animal for the Tibetans at Qinghai-Tibetan Plateau of China. The burden of parasitic diseases has been a major threat to the health of yaks at this region presenting a considerable socio-economic losses and impact to yak production and local nomads. Keeping in view, we collected the published papers from 1984 to 2017 on major parasitic infections in yaks by electronic literature search from five databases including CNKI, Google, PubMed, Science Direct and Web of Science. The prevalence of Eimeria, Babesia, Theileria, Hypodermosis, Cystic echinococcosis, Alveolar echinococcosis, Toxoplasma gondii, Neospora caninum, Cryptosporidium, Giardia duodenalis, Enterocytozoon bieneusi, Toxocara vitulorum, and Fascioliasis infection in yaks was found to be 48.02%, 13.06%, 36.11%, 59.85%, 16.93%, 0.99%, 20.50%, 5.14%, 10.00%, 3.68%, 4.07%, 22.23% and 28.7% respectively. Data presented are contemplated to enhance our current understanding on the major parasitic diseases of yaks at Qinghai Tibetan plateau, China. The main aim of this effort is to ameliorate the effects of the parasitic burden in this specie; so that, the attempts are made to minimize the incidence of these infections in future to raise the socio-economic levels of local community.

Development of sandwich Enzyme-Linked Immunosorbent Assay for the detection of porcine epidemic diarrhea virus in fecal samples

Porcine epidemic diarrhea virus (PEDV) causes acute diarrhea and dehydration in new-born piglets with subsequent economic losses to swine industry. In the current study, gene encoding of 381aa-792aa spike protein (S1) with the main epitope relative to virus neutralization of PEDV was amplified by RT-PCR and inserted into vector pET-30A(+). The plasmid was transferred into Escherichia coli BL21 (DE3). Meanwhile, recombinant protein expression was induced by isopropy1-β-galactopyranoside (IPTG). After denaturation and renaturation of inclusion bodies, the S1 protein was obtained by using purified recombinant S1 protein in immunized female BALB/c mice. Monoclonal antibodies (MAb) against S1 protein, named 4C7 by hybridoma technique were gained successfully. The result showed that MAb can specifically respond to S1 protein and PEDV via ELISA, Western bolt and immunofluorescence assay methods. A sandwich ELISA (S-ELISA) was established by using the captured monoclonal antibodies 4C7. The sensitivity and specificity were compared between S-ELISA and RT-PCR, which showed similar sensitivity and specificity. This work indicated that S-ELISA would be a significant tool alongside a specific diagnostic reagent for PEDV in future.

Equine Granulocytic Anaplasmosis 28 years later

Equine granulocytic anaplasmosis (EGA) is an important tick borne disease of equines that is caused by Anaplasma phagocytophilum (A. phagocytophilum). The etiological agent has veterinary as well as public health importance because of its zoonotic nature. A. phagocytophilum causes an acute illness in equines with loss of appetite, lethargy, hemorrhages and lameness. Clinically, EGA is diagnosed upon examination of morulae within neutrophils especially granulocytes in the blood. The best diagnostic tool for the detection of EGA is Polymerase chain reaction (PCR). Previous studies suggested that EGA is a self-limiting disease and tetracycline therapy is considered as a best treatment regimen. There is no comprehensive summary on the occurrence and distribution of the infection at global level. Therefore, we intended to provide a comprehensive summary on the prevalence and epidemiology of EGA in different areas of the world. It includes mapping the global distribution of EGA in different areas of the world to identify the endemic regions which may be a source of potential disease outbreak. For this purpose, the published data from 1990 to 2018 on EGA was reviewed and collected by electronic literature search of five databases including Google, Google Scholar, Science Direct, PubMed and Web of Science.