Screening of adhesive lactobacilli with antagonistic activity against Campylobacter jejuni

Survival Time of Campylobacter jejuni in Broiler Crops

Lactobacillus spp. inhibit the growth of Campylobacter spp. in vitro. However, in chicken crops, in which Lactobacillus spp. predominate, such inhibition of Campylobacter has not been confirmed. In our previous study, feeding paddy rice to broiler chicks increased the residence time of the food, which might enhance the bactericidal activity of the crop. Here, the bactericidal activity against the remaining Campylobacter spp. in broiler crops was evaluated. A suspension prepared by mixing Campylobacter jejuni and titanium dioxide (TiO2) was inoculated into the pharynx of 26-day-old broiler chicks fed a paddy rice-based diet. The crop contents were sampled at 20-min intervals. The TiO2 residual ratio in the crop gradually decreased with time after inoculation, with 57% of the inoculated TiO2 remaining in the crop 60 min after inoculation. The survival fraction of C. jejuni in the crops was 11% at 40 min, only 1% at 60 min, and was undetectable at 80 min. Most of the inoculated C. jejuni died in the crop before entering the next segment. These data indicated that bacterial death occurred between 30 min and 40 min after inoculation. The average survival time of C. jejuni in the crop was calculated to be 37.1 min. Thus, C. jejuni remaining in a chicken crop for more than 40 min died.

Metabolomic signatures of intestinal colonization resistance against Campylobacter jejuni in mice

Introduction

Campylobacter jejuni stands out as one of the leading causes of bacterial enteritis. In contrast to humans, specific pathogen-free (SPF) laboratory mice display strict intestinal colonization resistance (CR) against C. jejuni, orchestrated by the specific murine intestinal microbiota, as shown by fecal microbiota transplantation (FMT) earlier.

Methods

Murine infection models, comprising SPF, SAB, hma, and mma mice were employed. FMT and microbiota depletion were confirmed by culture and culture-independent analyses. Targeted metabolome analyses of fecal samples provided insights into the associated metabolomic signatures.

Results

In comparison to hma mice, the murine intestinal microbiota of mma and SPF mice (with CR against C. jejuni) contained significantly elevated numbers of lactobacilli, and Mouse Intestinal Bacteroides, whereas numbers of enterobacteria, enterococci, and Clostridium coccoides group were reduced. Targeted metabolome analysis revealed that fecal samples from mice with CR contained increased levels of secondary bile acids and fatty acids with known antimicrobial activities, but reduced concentrations of amino acids essential for C. jejuni growth as compared to control animals without CR.

Discussion

The findings highlight the role of microbiota-mediated nutrient competition and antibacterial activities of intestinal metabolites in driving murine CR against C. jejuni. The study underscores the complex dynamics of host-microbiota-pathogen interactions and sets the stage for further investigations into the mechanisms driving CR against enteric infections.

Investigation of the Suitability of a Combination of Ethyl-Να-dodecanyl-L-arginat_HCl (LAE) and Starter Culture Bacteria for the Reduction of Bacteria from Fresh Meat of Different Animal Species

Meat can be contaminated with (pathogenic) microorganisms during slaughter, dissection and packaging. Therefore, preservation technologies are frequently used to reduce the risk of (fatal) human infections due to the consumption of meat. In this study, we first investigated, if the application of ethyl-Nα-dodecanyl-L-arginate hydrochloride (LAE) and the starter culture bacteria Staphylococcus carnosus and Lactobacillus sakei, either single or in combination, influences the bacteria number on pork, chicken meat and beef, inoculated with Brochothrix (Br.) thermosphacta (all meat species) or Salmonella (S.) Typhimurium (pork), Campylobacter (C.) jejuni (chicken) and Listeria (L.) monocytogenes (beef), before packaging under modified atmosphere and on days 7 and 14 of storage. To evaluate effects of the treatment on the appearance during storage, additionally, the physicochemical parameters color and myoglobin redox form percentages were analyzed. LAE regularly resulted in a significant reduction of the number of all bacteria species on day 1 of storage, whereas up to day 14 of storage, the preservation effect did not persist in nearly all samples, except in the beef with Br. thermosphacta. However, with the starter culture bacteria on day 1, only L. monocytogenes on beef was significantly reduced. Interestingly, on day 7 of storage, this reducing effect was also found with S. Typhimurium on pork. Br. thermosphacta, which was principally not influenced by the starter culture bacteria. The combinatory treatment mainly resulted in no additional effects, except for the S. Typhimurium and Br. thermosphacta results on pork on day 7 and the Br. thermosphacta results on beef on day 14. The physicochemical parameters were not influenced by the single and combinatory treatment. The results indicate that LAE was mainly responsible for the antimicrobial effects and that a combination with starter culture bacteria should be individually evaluated for the meat species.

Identification of a new probiotic strain, Lactiplantibacillus plantarum VHProbi® V38, and its use as an oral health agent

Introduction

Probiotics can be used to treat oral diseases such as dental caries, gingivitis, periodontitis, and halitosis.

Methods

This study screened for strains capable of inhibiting Streptococcus mutans,one of the primary pathogenic bacteria responsible for dental caries by agar diffusion in different samples. Strain identification was performed by 16S rDNA sequencing and the API 50CH system. The potential functions of the strains in terms of oral health properties were also tested by agglutination assays, growth inhibition assays, adhesion assays, biofilm removal assays and inhibition of adhesion in human primary gingival epithelial (HPGE) cells assays.

Results

This study identified a probiotic strain from fermented cabbages that has a strong inhibitory effect on Streptococcus mutans. The API 50CH system and 16S rDNA sequencing verified that this was a new strain and it was given the name, Lactiplantibacillus plantarum VHProbi^®V38. Agglutination, growth inhibition and adhesion, and biofilm removal tests indicated that L. plantarum VHProbi^® V38 inhibited and reduced S. mutans. This probiotic was shown to have a broad antibacterial spectrum, simultaneously inhibiting the growth of periodontal pathogenic bacteria such as Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum. After 2 hours of co-cultivation with these pathogens, L. plantarum VHProbi^® V38 was able to significantly reduce pathogens adhesion on human primary gingival epithelial (HPGE) cells.

Discussion

These findings suggest that L. plantarum VHProbi^® V38 could potentially prevent and treat periodontal diseases caused by these pathogenic bacteria. L. plantarum VHProbi^® V38 also adheres strongly to HPGE cells and thus has potential as an oral probiotic. This study describes new methods that can be used to aid the screening and identification of oral probiotics.

Campylobacter jejuni in Poultry: Pathogenesis and Control Strategies

C. jejuni is the leading cause of human foodborne illness associated with poultry, beef, and pork consumption. C. jejuni is highly prevalent in commercial poultry farms, where horizontal transmission from the environment is considered to be the primary source of C. jejuni. As an enteric pathogen, C. jejuni expresses virulence factors regulated by a two-component system that mediates C. jejuni's ability to survive in the host. C. jejuni survives and reproduces in the avian intestinal mucus. The avian intestinal mucus is highly sulfated and sialylated compared with the human mucus modulating C. jejuni pathogenicity into a near commensal bacteria in poultry. Birds are usually infected from two to four weeks of age and remain colonized until they reach market age. A small dose of C. jejuni (around 35 CFU/mL) is sufficient for successful bird colonization. In the U.S., where chickens are raised under antibiotic-free environments, additional strategies are required to reduce C. jejuni prevalence on broilers farms. Strict biosecurity measures can decrease C. jejuni prevalence by more than 50% in broilers at market age. Vaccination and probiotics, prebiotics, synbiotics, organic acids, bacteriophages, bacteriocins, and quorum sensing inhibitors supplementation can improve gut health and competitively exclude C. jejuni load in broilers. Most of the mentioned strategies showed promising results; however, they are not fully implemented in poultry production. Current knowledge on C. jejuni's morphology, source of transmission, pathogenesis in poultry, and available preharvest strategies to decrease C. jejuni colonization in broilers are addressed in this review.

Leuconostoc mesenteroides LVBH107 Antibacterial Activity against Porphyromonas gingivalis and Anti-Inflammatory Activity against P. gingivalis Lipopolysaccharide-Stimulated RAW 264.7 Cells

Probiotics, active microorganisms benefiting human health, currently serve as nutritional supplements and clinical treatments. Periodontitis, a chronic infectious oral disease caused by Porphyromonas gingivalis (P. gingivalis), activates the host immune response to release numerous proinflammatory cytokines. Here, we aimed to clarify Leuconostoc mesenterica (L. mesenteroides) LVBH107 probiotic effects based on the inhibition of P.gingivalis activities while also evaluating the effectiveness of an in vitro P.gingivalis lipopolysaccharide-stimulated RAW 264.7 cell-based inflammation mode. L. mesenteroides LVBH107 survived at acid, bile salts, lysozyme, and hydrogen peroxide conditions, auto-aggregated and co-aggregated with P. gingivalis, exhibited strong hydrophobicity and electrostatic action, and strongly adhered to gingival epithelial and HT-29 cells (thus exhibiting oral tissue adherence and colonization abilities). Moreover, L.mesenteroides LVBH107 exhibited sensitivity to antibiotics erythromycin, doxycycline, minocycline, ampicillin, and others (thus indicating it lacked antibiotic resistance plasmids), effectively inhibited P.gingivalis biofilm formation and inflammation (in vitro inflammation model), reduced the secretion of pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) and inflammatory mediators (NO and PGE₂), and decreased the expression levels of inflammation related genes. Thus, L.mesenterica LVBH107 holds promise as a probiotic that can inhibit P.gingivalis biofilm formation and exert anti-inflammatory activity to maintain oral health.

In vitro and in vivo activity of Lactobacillus sakei L14 strain against Campylobacter jejuni DC3 strain

Introduction

Domestic poultry is a natural reservoir of Campylobacter, the host–pathogen interaction being predominantly asymptomatic. This study investigated whether chickens remain asymptomatic partly because of lactic acid bacteria (LAB).

Material and Methods

Campylobacter spp. and LAB were isolated from the gut of poultry chickens using enrichment and screening assays and were identified via rDNA sequencing. The C. jejuni DC3 isolate was grown in different cell-free supernatants (CFS) generated from a priority LAB isolate. An in vivo challenge involving the C. jejuni and LAB isolates using a chicken model was performed to confirm the in vitro findings.

Results

Twelve presumptive LAB isolates had anti-C. jejuni activity based on cross-streak and agar plug assays, with Lactobacillus sakei L14 isolate exhibiting the highest activity. Inhibition by L. sakei L14 CFS of the growth of C. jejuni occurred in a dose-dependent manner. Campylobacter jejuni DC3 inhibition was most evident in CFS harvested at 72 h and produced by co-culture with the pathogen. Neutralisation of the CFS abrogated the observed inhibition. Co-infection with C. jejuni DC3 and L. sakei L14 in vivo, however, failed to inhibit C. jejuni colonisation in chickens.

Conclusion

The results suggest that the anti-C. jejuni effect of L. sakei L14 in chickens may be due to mechanisms other than direct inhibition of growth.

Lactic acid bacteria that activate immune gene expression in Caenorhabditis elegans can antagonise Campylobacter jejuni infection in nematodes, chickens and mice

BACKGROUND

Campylobacter jejuni is the major micro-bacillary pathogen responsible for human coloenteritis. Lactic acid bacteria (LAB) have been shown to protect against Campylobacter infection. However, LAB with a good ability to inhibit the growth of C. jejuni in vitro are less effective in animals and animal models, and have the disadvantages of high cost, a long cycle, cumbersome operation and insignificant immune response indicators. Caenorhabditis elegans is increasingly used to screen probiotics for their anti-pathogenic properties. However, no research on the use of C. elegans to screen for probiotic candidates antagonistic to C. jejuni has been conducted to date.

RESULTS

This study established a lifespan model of C. elegans, enabling the preselection of LAB to counter C. jejuni infection. A potential protective mechanism of LAB was identified. Some distinct LAB species offered a high level of protection to C. elegans against C. jejuni. The LAB strains with a high protection rate reduced the load of C. jejuni in C. elegans. The transcription of antibacterial peptide genes, MAPK and Daf-16 signalling pathway-related genes was elevated using the LAB isolates with a high protection rate. The reliability of the lifespan model of C. elegans was verified using mice and chickens infected with C. jejuni.

CONCLUSIONS

The results showed that different LAB had different abilities to protect C. elegans against C. jejuni. C. elegans provides a reliable model for researchers to screen for LAB that are antagonistic to C. jejuni on a large scale.

The Use of Probiotics in the Reduction of Campylobacter spp. Prevalence in Poultry

Campylobacter spp. are widely distributed microorganisms, many of which are commensals of gastrointestinal tract in multiple animal species, including poultry. Most commonly detected are C. jejuni and C. coli. Although infections are usually asymptomatic in poultry, poultry meat and products represent main sources of infection with these bacteria to humans. According to recent EFSA report, campylobacteriosis is the most commonly reported zoonotic disease. In 2018, EFSA Panel on Biological Hazards indicated that use of feed and water additives is the second most likely strategy that can be successful in minimizing Campylobacter spp. colonization rate in broiler chickens. One of those feed and water additives are probiotics. From numerous research papers it can be concluded that probiotics exhibit plenty of mechanisms of anti-Campylobacter activity, which were evaluated under in vitro conditions. These results, to some extent, can explain the efficacy of probiotics in in vivo studies, although different outcome can be observed under these two laboratory conditions. Probiotics are capable of reducing Campylobacter spp. population count in poultry gastrointestinal tract and they can reduce carcass contamination. Potential modes of anti-Campylobacter activity of probiotics, results of in vivo studies and studies performed at a farm level are widely discussed in the paper.

Metagenomic Analysis of the Gut Microbiota of Wild Mice, a Newly Identified Reservoir of Campylobacter

Campylobacter, the most common etiologic agent of zoonotic gastroenteritis in humans, is present in many reservoirs including livestock animals, wildlife, soil, and water. Previously, we reported a novel Campylobacter jejuni strain SCJK02 (MLST ST-8388) from the gut of wild mice (Micromys minutus) using culture-dependent methods. However, due to fastidious growth conditions and the presence of viable but non-culturable Campylobacter spp., it is unclear whether M. minutus is a Campylobacter reservoir. This study aimed to: 1) determine the distribution and proportion of Campylobacter spp. in the gut microbiota of wild mice using culture-independent methods and 2) investigate the gut microbiota of wild mice and the relationship of Campylobacter spp. with other gut microbes. The gut microbiota of 38 wild mice captured from perilla fields in Korea and without any clinical symptoms (18 M. minutus and 20 Mus musculus) were analyzed. Metagenomic analysis showed that 77.8% (14 of 18) of the captured M. minutus harbored Campylobacter spp. (0.24–32.92%) in the gut metagenome, whereas none of the captured M. musculus carried Campylobacter spp. in their guts. Notably, 75% (6 of 8) of M. minutus determined to be Campylobacter-negative using culture-dependent methods showed a high proportion of Campylobacter through metagenome analysis. The results of metagenome analysis and the absence of clinical symptoms suggest that Campylobacter may be a component of the normal gut flora of wild M. minutus. Furthermore, linear discriminant analysis (LDA) showed that Campylobacter was the most enriched genus in the gut microbiota of M. minutus (LDA score, 5.37), whereas Lactobacillus was the most enriched genus in M. musculus (LDA score, −5.96). The differences in the presence of Campylobacter between the two species of wild mice may be attributed to the differential abundance of Campylobacter and Lactobacillus in their respective gut microbiota. In conclusion, the results indicate that wild M. minutus may serve as a potential Campylobacter reservoir. This study presents the first metagenomics analysis of the M. minutus gut microbiota to explore its possible role as an environmental Campylobacter reservoir and provides a basis for future studies using culture-independent methods to determine the role of environmental reservoirs in Campylobacter transmission.

Synergistic Effect of Eugenol and Probiotic Lactobacillus Plantarum Zs2058 Against Salmonella Infection in C57bl/6 Mice

Previously, we showed the preventive effects of Lactobacillus plantarum ZS2058 (ZS2058) on Salmonella infection in murine models. In this work, we found that eugenol has a selective antibacterial effect, which inhibited Salmonella more than probiotics ZS2058 in vitro. It suggested a synergistic effect of them beyond their individual anti-Salmonella activity. We verified the conjecture in murine models. The results showed that the combination of ZS2058 and eugenol (CLPZE) significantly increased (p = 0.026) the survival rate of Salmonella-infected mice from 60% to 80% and the effect of CLPZE on preventing Salmonella-infection was 2-fold that of ZS2058 alone and 6-fold that of eugenol alone. CLPZE had a synergistic effect on inhibiting ST growth (the coefficient drug interaction ((CDI) = 0.829), reducing its invasiveness (CDI = 0.373) and downregulating virulence genes’ expression in vitro. CLPZE helped the host form a healthier gut ecosystem. CLPZE also elicited a stronger and earlier immune response to systemic infection. In conclusion, these obtained results suggest that ZS2058 and eugenol have a synergistic effect on preventing Salmonella infection and open new perspectives in the strategies of controlling the prevalence of Salmonella by combination of probiotics and functional food components.

Effect of Lactobacillus spp. on adhesion, invasion, and translocation of Campylobacter jejuni in chicken and pig small-intestinal epithelial cell lines

BACKGROUND

Campylobacter spp. are a major cause of bacterial food-borne diarrhoeal disease. This mainly arises through contamination of meat products during processing. For infection, Campylobacter spp. must adhere to epithelial cells of the mucus layer, survive conditions of the gastrointestinal tract, and colonise the intestine of the host. Addition of probiotic bacteria might promote competitive adhesion to epithelial cells, consequently reducing Campylobacter jejuni colonisation. Effect of Lactobacillus spp. (PCS20, PCS22, PCS25, LGG, PCK9) on C. jejuni adhesion, invasion and translocation in pig (PSI cl.1) and chicken (B1OXI) small-intestine cell lines, as well as pig enterocytes (CLAB) was investigated.

RESULTS

Overall, in competitive adhesion assays with PSI cl.1 and CLAB cell monolayers, the addition of Lactobacillus spp. reduced C. jejuni adherence to the cell surface, and negatively affected the C. jejuni invasion. Interestingly, Lactobacillus spp. significantly impaired C. jejuni adhesion in three-dimensional functional PSI cl.1 and B1OXI cell models. Also, C. jejuni did not translocate across PSI cl.1 and B1OXI cell monolayers when co-incubated with probiotics. Among selected probiotics, Lactobacillus rhamnosus LGG was the strain that reduced adhesion efficacy of C. jejuni most significantly under co-culture conditions.

CONCLUSION

The addition of Lactobacillus spp. to feed additives in livestock nutrition might be an effective novel strategy that targets Campylobacter adhesion to epithelial cells, and thus prevents colonisation, reduces the transmission, and finally lowers the incidence of human campylobacteriosis.

Effects of Lactococcus lactis from Cyprinus carpio L. as probiotics on growth performance, innate immune response and disease resistance against Aeromonas hydrophila

In the present study, we reported 18 LAB strains isolated from the intestinal contents of Cyprinus carpio, and their probiotic properties both in vitro and in vivo. The results showed that 9 of them had higher in vitro immunomodulatory properties, effectively survived under acidic (pH 2.5) and bile salt (ranging from 0.1% to 0.5%) conditions, and inhibited the growth of 4 pathogens. Among them, Lactococcus lactis Q-8, Lactococcus lactis Q-9, and Lactococcus lactis Z-2 showed the strongest adhesion abilities and inhibition of pathogen adhesion to mucin. When the fish consumed diets containing these 3 strains (5 × 10⁸ CFU/g) for 8 weeks, the weight gain (WG) and specific growth rate (SGR) had significantly (P < 0.05) increased, especially with L. lactis Q-8, which had a WG of 231.45%, and SGR of 2.22%. Survival rate in each LAB supplementation group was also significantly higher than that in control group during the feeding period (P < 0.05). For the cytokines expression levels in serum, different expression patterns were also observed. Before the infection with Aeromonas hydrophila, L. lactis supplementation significant up-regulated protein levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-12) compared with negative (CK1) group, while these cytokines were significantly lower than those in positive (CK2) group after infection. However, whether infected or not, the expression of anti-inflammatory cytokines (IL-10, TGF-β) were significantly increased in L. lactis Q-8, L. lactis Q-9, and L. lactis Z-2 treatment groups. In conclusion, these 3 L. lactis strains screened from common carp were effective in improving growth, innate immunity and disease resistance. Based on the physiological characteristics in our study, they might be used as potential probiotics in aquaculture.

Adhesion to pharyngeal epithelium and modulation of immune response: Lactobacillus salivarius AR809, a potential probiotic strain isolated from the human oral cavity

Microbiome modulators such as probiotics are known to modulate oral diseases. Very few probiotics are commercially available for use in the oral cavity. In this context, we selected human-origin Lactobacillus salivarius AR809 as a promising oropharyngeal probiotic and characterized its functional and immunomodulatory properties. Results demonstrated that AR809 could efficiently adhere to pharyngeal epithelial FaDu cells, antagonize Staphylococcus aureus, adapt to the oral environment, and modulate host innate immunity by inducing potentially protective effects. Particularly, AR809 diminished proinflammatory activity by enhancing the production of IL10 and inhibiting the expression of tumor necrosis factor-α, IL1B, inducible nitric oxide synthase, and RELA. Finally, we observed that AR809 grew efficiently when cultured in milk, suggesting that the preparation of a fermented milk product containing AR809 could be a practical way to administer this probiotic to humans. In conclusion, AR809 has high potential to adhere to the pharyngeal mucosa and could be applied in novel milk-based probiotic fermented food products.

Strain-specific properties of Lactobacillus plantarum for prevention of Salmonella infection

Salmonella is a common food-borne pathogen; since lactobacilli show great potential for protecting against Salmonella infections, they are used as dietary supplements in functional foods. The aim of this study is to investigate the strain-specific properties and the involved mechanisms of action of Lactobacillus plantarum towards prevention of Salmonella infection. Mice were pretreated with mixed strains or single strain of Lactobacillus plantarum for 10 d prior to infection with Salmonella typhimurium SL1344, and the survival rates showed that lactobacilli exhibited strain-specific properties for preventing Salmonella infection. Then, in vitro and in vivo studies were carried out to investigate the involved mechanism of the strain-specific properties. The results showed that different Lactobacillus plantarum strains had different effects on inhibiting Salmonella growth, thus preventing adhesion to and invasion of epithelial cells by pathogens and enhancing immune responses. The present study demonstrated strain-specific properties of probiotics to prevent Salmonella infection and elucidated their underlying mechanisms.

Lactobacillus paracasei K5 displays adhesion, anti-proliferative activity and apoptotic effects in human colon cancer cells

Lactobacillus paracasei K5 is a lactic acid bacteria (LAB) strain, isolated recently from feta-type cheese. Its probiotic potential has been demonstrated in a series of established in vitro tests. Moreover, incorporation of L. paracasei K5 as starter culture offered organoleptic and technological advantages to novel fermented food products. In the present study, further investigation of the potential probiotic activity of L. paracasei K5 was performed and its mechanisms of action were investigated. Employing quantitative analysis and confocal, fluorescent microscopy the adhesion properties of the above strain were studied. L. paracasei K5 displayed efficient adherence capacity to Caco-2 colon cancer cells, similarly to the reference strains Lactobacillus casei ATCC 393 and Lactobacillus rhamnosus GG. Moreover, treatment of Caco-2 cells with L. paracasei K5 inhibited cell proliferation in a time-and dose-dependent manner. The anti-proliferative effects appear to be mediated through induction of apoptosis via modulation of expression of specific Bcl-2 family proteins. These results elucidate the mechanisms of action of L. paracasei K5 and enhance its potential probiotic activity.

Evaluation of probiotic Lactobacillus plantarum against foodborne pathogens and its fermentation potential in improving Lolium multiflorum silage quality

The objective of this study was to isolate the lactic acid bacteria from fermented silage sample and analyze their antibacterial activities, probiotic properties, and fermentation potential in silage. Eleven lactic acid bacteria (LAB) were selected based on distinct morphologies and preliminary studies. Cell-free supernatant (CFS) was then prepared from the selected strains for antibacterial analysis. L-30 strain and its CFS showed highest inhibition (> 10 mm) against tested foodborne pathogens as compared to other strains. Hereafter, the strain L-30 was named as KCC-30 and used for further studies. KCC-30 can survive in the harsh conditions of GIT such as low pH ( 2) and bile salt environment (oxgal) than standard L. plantarum KACC-91016 (pH 2: 27.2% vs 20.5%; oxgal: 72.3% vs 57.7%, both p < 0.05). In addition, KCC-30 exhibited strong auto-aggregation (68.3% vs 51.5%) and co-aggregation (33% vs 23.9%) properties. For silage experiment, KCC-30 treatment did not alter the nutrient profiles of silage. At the same time, KCC-30 treatment increased the lactic acid content of silage as compared to untreated silage (5.55 DM% vs 3.11 DM%). An increase of lactic acid content in the silage is due to higher lactic acid bacteria population in KCC-30 treated silage (15.33 × 10⁷ CFU/g vs 7.66 × 10⁷ CFU/g) than untreated silage (p < 0.05). Overall data suggested that KCC-30 exhibited strong probiotic potential and improved the quality of Lolium multiflorum silage by increasing the lactic acid level. Therefore, KCC-30 could be considered as potential strain to improve the fermentation quality of L. multiflorum silage.

Probiotic potential of Lactobacillus isolates of chicken origin with anti-Campylobacter activity

Campylobacteriosis is currently the most frequent zoonosis in humans and the main source of infection is contaminated poultry meat. As chickens are a natural host for Campylobacter species, one strategy to prevent infection in humans is to eliminate these bacteria on poultry farms. A study was conducted to evaluate the probiotic potential of 46 Lactobacillus isolates from chickens faeces or cloacae. All lactobacilli were able to produce active compounds on solid media with antagonistic properties against C. jejuni and C. coli, with L. salivarius and L. reuteri exhibiting particularly strong antagonism. The cell-free culture supernatants had a much weaker inhibitory effect on the growth of Campylobacter, and the neutralization of organic acids caused them to completely lose their inhibitory properties. The ability to produce H2O2 was exhibited by 93% of isolates; most of isolates had a hydrophobic surface, showed excellent survival at pH 2.0 or 1.5, and displayed tolerance to bile; 50% isolates displayed the ability to biofilm formation. Determination of MICs of various antibiotics showed that as much as 80.4% of Lactobacillus isolates were resistant to at least one antimicrobial agent. Seven ultimately selected isolates that met all the basic criteria for probiotics may have potential application in reducing Camylobacter spp. in chickens and thus prevent infections in both birds and humans.

Probiotics Strains Modulate Gut Microbiota and Lipid Metabolism in Mule Ducks

Background:

Livestock production should respond to societal, environmental and economic changes. Since 2006 and the ban on antibiotics as growth factors in European Union, the use of probiotics has become widespread and has demonstrated the effect of intestinal microbiota on the performance of farm animals.

Objective:

The aim of this study was to investigate the effect of supplementation with Lactobacillus salivarius (as a probiotics strain or combined with other strains) on zootechnical performance, metabolic and immune gene expression and intestinal microbiota diversity in mule ducks using high-throughput sequencing and real-time PCR.

Method:

The mule ducks were reared for 79 days and overfed for 12 days with or without probiotics. Samples were collected at 14 (starting period) and 91 days (end of overfeeding period), 3 hours post feeding.

Results:

Irrespective of digestive content, age, level of feed intake or supplementation with probiotics, Firmicutes, Proteobacteria and Bacteroidetes were the dominant phyla in the bacterial community in mule ducks. At 14 days, both the ileal and cecal samples were dominated by Firmicutes (in particular the Clostridiales order). Overfeeding induced a shift between Clostridiales and Lactobacillales in the ileal samples whereas in the cecal samples, the relative abundance of Firmicutes decreased. Overfeeding also induced hepatic over-expression of Fatty Acid Synthase (FAS) and of the lipid transporter gene Fatty Acid Binding Protein 4 (FABP4). This increase in lipid metabolism genes is associated with a decrease in inflammatory response.

Conclusion:

Finally, probiotic supplementation had only a slight impact on gene expression and microbiota diversity, both at 14 days and after overfeeding.

Current and Potential Treatments for Reducing Campylobacter Colonization in Animal Hosts and Disease in Humans

Campylobacter jejuni is the leading cause of bacteria-derived gastroenteritis worldwide. In the developed world, Campylobacter is usually acquired by consuming under-cooked poultry, while in the developing world it is often obtained through drinking contaminated water. Once consumed, the bacteria adhere to the intestinal epithelium or mucus layer, causing toxin-mediated inhibition of fluid reabsorption from the intestine and invasion-induced inflammation and diarrhea. Traditionally, severe or prolonged cases of campylobacteriosis have been treated with antibiotics; however, overuse of these antibiotics has led to the emergence of antibiotic-resistant strains. As the incidence of antibiotic resistance, emergence of post-infectious diseases, and economic burden associated with Campylobacter increases, it is becoming urgent that novel treatments are developed to reduce Campylobacter numbers in commercial poultry and campylobacteriosis in humans. The purpose of this review is to provide the current status of present and proposed treatments to combat Campylobacter infection in humans and colonization in animal reservoirs. These treatments include anti-Campylobacter compounds, probiotics, bacteriophage, vaccines, and anti-Campylobacter bacteriocins, all of which may be successful at reducing the incidence of campylobacteriosis in humans and/or colonization loads in poultry. In addition to reviewing treatments, we will also address several proposed targets that may be used in future development of novel anti-Campylobacter treatments.

Purification of Antilisterial Peptide (Subtilosin A) from Novel Bacillus tequilensis FR9 and Demonstrate Their Pathogen Invasion Protection Ability Using Human Carcinoma Cell Line

This study focuses on isolation, screening, and characterization of novel probiotics from gastrointestinal tract of free-range chicken (Gallus gallus domesticus). Fifty seven colonies were isolated and three isolates (FR4, FR9, and FR12) were selected and identified as Lactobacillus gasseri FR4, Bacillus tequilensis FR9, and L. animalis FR12 by 16S rRNA sequencing. Three strains were able to survive in stimulated acidic and bile conditions and inhibit the growth of pathogens. Especially, FR9 exhibited maximum inhibition against Listeria monocytogenes and none of them exhibited hemolytic activity. Native-PAGE revealed the presence of low molecular weight (3.4-5.0 KDa) antimicrobial peptide. The peptide was further purified by Sephadex G-50 column and RP-HPLC using C18 column. N-terminal amino acid sequencing of antimicrobial peptide showed 100% consensus to antilisterial peptide Subtilosin A and SboA gene was amplified from FR9 genome. FR9 showed maximum aggregation activity, exopolysaccharide production (85.46 mg/L) and cholesterol assimilation (63.12 ± 0.05 μg/mL). Strong adhesion property (12.6%) and pathogen invasion protection ability was revealed by B. tequilensis FR9 towards HCT-116 human colon carcinoma cell line. This is the first study to demonstrate antilisterial Subtilosin A production of B. tequilensis. Our results indicate that B. tequilensis FR9 strain furnish the essential characteristics of a potential probiotics and might be incorporated into human and animal food supplements.

Recent Advances in Screening of Anti-Campylobacter Activity in Probiotics for Use in Poultry

Campylobacteriosis is the most common cause of bacterial gastroenteritis worldwide. Campylobacter species involved in this infection usually include the thermotolerant species Campylobacter jejuni. The major reservoir for C. jejuni leading to human infections is commercial broiler chickens. Poultry flocks are frequently colonized by C. jejuni without any apparent symptoms. Risk assessment analyses have identified the handling and consumption of poultry meat as one of the most important sources of human campylobacteriosis, so elimination of Campylobacter in the poultry reservoir is a crucial step in the control of this foodborne infection. To date, the use of probiotics has demonstrated promising results to reduce Campylobacter colonization. This review provides recent insights into methods used for probiotic screening to reduce the prevalence and colonization of Campylobacter at the farm level. Different eukaryotic epithelial cell lines are employed to screen probiotics with an anti-Campylobacter activity and yield useful information about the inhibition mechanism involved. These in vitro virulence models involve only human intestinal or cervical cell lines whereas the use of avian cell lines could be a preliminary step to investigate mechanisms of C. jejuni colonization in poultry in the presence of probiotics. In addition, in vivo trials to evaluate the effect of probiotics on Campylobacter colonization are conducted, taking into account the complexity introduced by the host, the feed, and the microbiota. However, the heterogeneity of the protocols used and the short time duration of the experiments lead to results that are difficult to compare and draw conclusions at the slaughter-age of broilers. Nevertheless, the combined approach using complementary in vitro and in vivo tools (cell cultures and animal experiments) leads to a better characterization of probiotic strains and could be employed to assess reduced Campylobacter spp. colonization in chickens if some parameters are optimized.

Use of Lactobacillus plantarum Strains as a Bio-Control Strategy against Food-Borne Pathogenic Microorganisms

Lactobacillus plantarum is one of the most versatile species extensively used in the food industry both as microbial starters and probiotic microorganisms. Several L. plantarum strains have been shown to produce different antimicrobial compounds such as organic acids, hydrogen peroxide, diacetyl, and also bacteriocins and antimicrobial peptides, both denoted by a variable spectrum of action. In recent decades, the selection of microbial molecules and/or bacterial strains able to produce antagonistic molecules to be used as antimicrobials and preservatives has been attracting scientific interest, in order to eliminate or reduce chemical additives, because of the growing attention of consumers for healthy and natural food products. The aim of this work was to investigate the antimicrobial activity of several food-isolated L. plantarum strains, analyzed against the pathogenic bacteria Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli O157:H7 and Staphylococcus aureus. Antagonistic activity was assayed by agar spot test and revealed that strain L. plantarum 105 had the strongest ability to contrast the growth of L. monocytogenes, while strains L. plantarum 106 and 107 were the most active microorganisms against E. coli O157:H7. The antimicrobial ability was also screened by well diffusion assay and broth micro-dilution method using cell-free supernatants (CFS) from each Lactobacillus strain. Moreover, the chemical nature of the molecules released in the CFS, and possibly underlying the antagonistic activity, was preliminary characterized by exposure to different constraints such as pH neutralization, heating, catalase, and proteinase treatments. Our data suggest that the ability of L. plantarum cultures to contrast pathogens growth in vitro depends, at least in part, on a pH-lowering effect of supernatants and/or on the presence of organic acids. Cluster analysis was performed in order to group L. plantarum strains according to their antimicrobial effect. This study emphasizes the tempting use of the tested L. plantarum strains and/or their CFS as antimicrobial agents against food-borne pathogens.