Competitive reduction of poultry-borne enteric bacterial pathogens in chicken gut with bioactive Lactobacillus casei

Dietary Supplementation of Brevibacillus laterosporus S62-9 Improves Broiler Growth and Immunity by Regulating Cecal Microbiota and Metabolites

Brevibacillus laterosporus has been added as a direct-fed microbiota to chicken. Yet, few studies have reported the effects of B. laterosporus on broiler growth and gut microbiota. The aim of this study was to evaluate the effects of B. laterosporus S62-9 on growth performance, immunity, cecal microbiota, and metabolites in broilers. A total of 160 1-day-old broilers were randomly divided into S62-9 and control groups, with or without 106 CFU/g B. laterosporus S62-9 supplementation, respectively. During the 42 days feeding, body weight and feed intake were recorded weekly. Serum was collected for immunoglobulin determination, and cecal contents were taken for 16S rDNA analysis and metabolome at Day 42. Results indicated that the broilers in S62-9 group showed an increase in body weight of 7.2% and 5.19% improvement in feed conversion ratio compared to the control group. The B. laterosporus S62-9 supplementation promoted the maturation of immune organs and increased the concentration of serum immunoglobulins. Furthermore, the α-diversity of cecal microbiota was improved in the S62-9 group. B. laterosporus S62-9 supplementation increased the relative abundance of beneficial bacteria including Akkermansia, Bifidobacterium, and Lactobacillus, while decreased the relative abundance of pathogens including Klebsiella and Pseudomonas. Untargeted metabolomics revealed that 53 differential metabolites between the two groups. The differential metabolites were enriched in 4 amino acid metabolic pathways, including arginine biosynthesis and glutathione metabolism. In summary, B. laterosporus S62-9 supplementation could improve the growth performance and immunity through the regulation of gut microbiota and metabolome in broilers.

Identification of novel probiotic lactic acid bacteria from soymilk waste using the 16s rRNA gene for potential use in poultry

Background and Aim

In-feed antibiotics have been used as antibiotic growth promoters (AGPs) to enhance the genetic potential of poultry. However, the long-term use of AGPs is known to lead to bacterial resistance and antibiotic residues in poultry meat and eggs. To address these concerns, alternatives to AGPs are needed, one of which is probiotics, which can promote the health of livestock without having any negative effects. In vitro probiotic screening was performed to determine the ability of lactic acid bacteria (LAB) isolated from soymilk waste to be used as a probiotic for livestock.

Materials and Methods

Four LAB isolates (designated F4, F6, F9, and F11) isolated from soymilk waste were used in this study. In vitro testing was performed on LAB isolates to determine their resistance to temperatures of 42°C, acidic pH, bile salts, hydrophobicity to the intestine, and ability to inhibit pathogenic bacteria. A promising isolate was identified using the 16S rRNA gene.

Result

All LAB isolates used in this study have the potential to be used as probiotics. On the basis of the results of in vitro testing, all isolates showed resistance to temperatures of 42°C and low pH (2.5) for 3 h (79.87%-94.44%) and 6 h (76.29%-83.39%), respectively. The survival rate at a bile salt concentration of 0.3% ranged from 73.24% to 90.39%, whereas the survival rate at a bile salt concentration of 0.5% ranged from 56.28% to 81.96%. All isolates showed the ability to attach and colonize the digestive tract with a hydrophobicity of 87.58%-91.88%. Inhibitory zones of LAB against pathogens ranged from 4.80-15.15 mm against Staphylococcus aureus, 8.85-14.50 mm against Salmonella enteritidis, and 6.75-22.25 mm against Escherichia coli. Although all isolates showed good ability as probiotics, isolate F4 showed the best probiotic ability. This isolate was identified as Lactobacillus casei strain T22 (JQ412731.1) using the 16S rRNA gene.

Conclusion

All isolates in this study have the potential to be used as probiotics. However, isolate F4 has the best probiotic properties and is considered to be the most promising novel probiotic for poultry.

Systematic review on microbiome-related nutritional interventions interfering with the colonization of foodborne pathogens in broiler gut to prevent contamination of poultry meat

This systematic review aimed to compile the available body of knowledge about microbiome-related nutritional interventions contributing to improve the chicken health and having an impact on the reduction of colonization by foodborne pathogens in the gut. Original research articles published between 2012 and 2022 were systematically searched in Scopus and PubMed. A total of 1,948 articles were retrieved and 140 fulfilled the inclusion criteria. Overall, 73 papers described 99 interventions against colonization by Escherichia coli and related organisms; 10 papers described 15 interventions against Campylobacter spp.; 36 papers described 54 interventions against Salmonella; 40 papers described 54 interventions against Clostridium perfringens. A total of 197 microbiome-related interventions were identified as effective against one or more of the listed pathogens and included probiotics (n = 80), prebiotics (n = 23), phytobiotics (n = 25), synbiotics (n = 12), organic acids (n = 12), enzymes (n = 4), essential oils (n = 14) and combination of these (n = 27). The identified interventions were mostly administered in the feed (173/197) or through oral gavage (11/197), in the drinking water (7/197), in ovo (2/197), intra amniotic (2/197), in fresh or reused litter (1/197) or both in the feed and water (1/197). The interventions enhanced the beneficial microbial communities in the broiler gut as Lactic acid bacteria, mostly Lactobacillus spp., or modulated multiple microbial populations. The mechanisms promoting the fighting against colonization by foodborne pathogens included competitive exclusion, production of short chain fatty acids, decrease of gut pH, restoration of the microbiome after dysbiosis events, promotion of a more stable microbial ecology, expression of genes improving the integrity of intestinal mucosa, enhancing of mucin production and improvement of host immune response. All the studies extracted from the literature described in vivo trials but performed on a limited number of animals under experimental settings. Moreover, they detailed the effect of the intervention on the chicken gut without details on further impact on poultry meat safety.

Determining the In Vivo Efficacy of Plant-Based and Probiotic-Based Antibiotic Alternatives against Mixed Infection with Salmonella enterica and Escherichia coli in Domestic Chickens

Restrictions on the use of antimicrobial compounds have led to a surge of interest in alternative solutions, such as natural, plant-based compounds. In our study, we investigated the efficacy of three feed supplements containing different additives, namely, probiotics (Lactobacillus spp., "Test substance A"), turmeric (Curcuma longa L., "Test substance B"), and fenugreek (Trigonella foenum graecum, "Test substance C"). In the experiment, we tested 180 birds of the Bábolna Tetra-SL laying hybrid breed that were infected with Salmonella enteritidis strains. The birds were randomly divided into six groups: three groups treated with the different additives, a negative control group, a positive control group, and an antibiotic-treated group using enrofloxacin. We examined the maturation and the time course of shedding of Salmonella; at the end of rearing, pathological and histopathological examinations were performed. When Salmonella was isolated from the cloacal swab samples, the enrofloxacin-treated group had a high number of animals shedding Salmonella by day 9, which was like the group treated with test material C. The greatest reduction in Salmonella shedding was observed in the groups treated with test materials A and B. In terms of pathological parameters, villus length and crypt depth were significantly better in the group treated with test material C compared to the positive and negative controls, and when comparing the body weight of the tested animals, the group treated with test material B had a significantly larger absorption surface area compared to the positive control group. Overall, the supplement with test material C proved to be the most effective. In the future, it is worthwhile to investigate the combination of the tested active substances for their possible synergistic effects and to perform a dose-response study to select the optimal dosage.

Prophylactic influences of prebiotics on gut microbiome and immune response of heat-stressed broiler chickens

Climatic changes and elevated ambient temperature are significant environmental stressors with a negative impact on birds' physiological, immunological, and behavioral status, increasing their susceptibility to stressors and immunosuppression and consequently increasing intestinal permeability (leaky gut). Prebiotics have been utilized to stop or diminish the harmful effects of stress in chickens. We aimed to evaluate the role of mannan-oligosaccharides, and beta-D-glucan prebiotics supplements in drinking water against experimentally induced heat stress (HS) on broiler chickens and study their impact on birds' performance, gut microbiome, and immune response. A total of 120 1-day-old Ross broiler chicks were allocated into four groups (30 birds/group), and each group was subdivided into triplicates (10 birds each). The experimental groups were classified as follows; the 1st (G1) control birds, the 2nd (G2) birds exposed experimentally to HS, the 3rd (G3) birds administered prebiotics in drinking water without exposure to HS, and the 4th (G4) birds exposed to HS and administered prebiotics in drinking water. After each vaccination, blood samples and serum samples were collected to evaluate the birds' immune status. Fecal samples were also collected for the molecular evaluation of the gut microbiome based on the genetic analyses and sequencing of 16S rRNA gene. The results showed that HS has reduced the birds' performance and badly affected the birds' immune response and gut microbiome. However, the addition of prebiotics to drinking water, with or without stress, enhanced the growth rate, maintained a normal gut microbiome, and improved immune parameters. Moreover, the usage of prebiotics improved the chicken gut microbiome and alleviated the negative effect of heat stress. Administering prebiotics significantly (p < 0.05) increased the relative abundance of beneficial bacteria and eradicated pathogenic ones in the birds' gut microbiome. Prebiotics showed a positive effect on the gut microbiome and the immune status of chickens under HS in addition to their efficacy as a growth promoter.

Dietary Lactobacillus reuteri SL001 Improves Growth Performance, Health-Related Parameters, Intestinal Morphology and Microbiota of Broiler Chickens

It was assumed that dietary inclusion of Lactobacillus reuteri SL001 isolated from the gastric contents of rabbits could act as an alternative to feed antibiotics to improve the growth performance of broiler chickens. We randomly assigned 360 one-day-old AA white-feathered chicks in three treatments: basal diet (control), basal diet plus zinc bacitracin (antibiotic), and basal diet plus L. reuteri SL001 (SL001) treatment. The results showed the total BW gain and average daily gain (ADG) of broilers in SL001 treatment increased significantly (p < 0.05, respectively) compared with the control group from day 0 to 42. Moreover, we observed higher levels of immune globulins in both the SL001 group and the antibiotic group. Total antioxidant capacity and levels of antioxidant factors were also significantly increased (p ≤ 0.05, respectively) in the SL001 treatment group, while the interleukin 6, interleukin 4, creatinine, uric acid, total cholesterol, triglyceride, VLDL, LDL and malondialdehyde were remarkably decreased (p < 0.05, respectively). In the ileum of SL001 treatment broilers, the height of villi and the ratio of villi height to crypt depth were significantly increased (p < 0.05). Meanwhile, the crypt depth reduced (p < 0.01) and the ratio of villi height to crypt depth increased (p < 0.05) in the jejunum compared to the control. The abundance of microbiota increased in the gut of broilers supplemented with SL001. Dietary SL001 significantly increased the relative abundance of Actinobacteria in the cecal contents of broilers (p < 0.01) at the phylum level. In conclusion, L. reuteri SL001 supplementation promotes the growth performance of broiler chickens and exhibits the potential application value in the industry of broiler feeding.

Modulation of the immune system of chickens a key factor in maintaining poultry production-a review

The awareness of poultry production safety is constantly increasing. The safety of poultry production is defined as biosecurity and the health status of birds. Hence the constant pursuit of developing new strategies in this area is necessary. Biosecurity is an element of good production practices that ensures adequate hygiene and maintaining the health status of poultry production. Poultry production is the world leader among all livestock species. Producers face many challenges during rearing, which depend on the utility type, the direction of use, and consumer requirements. For many years, the aim was to increase production results. Increasing attention is paid to the quality of the raw material and its safety. Therefore, it is crucial to ensure hygiene status during production. It can affect the immune system's functioning and birds' health status. Feed, water, and environmental conditions, including light, gases, dust, and temperature, play an essential role in poultry production. This review aims to look for stimulators and modulators of the poultry immune system while affecting the biosecurity of poultry production. Such challenges in current research by scientists aim to respond to the challenges posed as part of the One Health concept. The reviewed issues are a massive potential for an innovative approach to poultry production and related risks as part of the interaction of the animal-human ecosystem.

Alternative approaches to therapeutics and subtherapeutics for sustainable poultry production

The world population is growing rapidly and thus its demand for food is growing as well. To meet the demand of the ever-increasing number of consumers, the poultry industry and both of its main sectors-conventional and organic/cage-free farming-are expanding in parallel. Due to increasing demand of poultry products and higher mortality rate of chicks (an average 0.3% increase of mortality over last 5 yr), both conventional and organic poultry farming systems struggle with various issues; animal welfare, environmental sustainability, and antibiotic resistance of the prevailing zoonotic/enteric pathogens are common issues for conventional farming whereas slow growth rate, higher costs, inefficient land use, different diseases of the chicken, and cross-contamination with bacterial pathogens into the final products are the major issues for organic poultry farming. On top of these issues, the use of subtherapeutic antibiotics was recently banned in conventional farming systems and by definition the organic farming system cannot use the antibiotics/synthetic chemicals even for therapeutic use. In conventional farming system, use of therapeutic antibiotics may result in residuals antibiotics in the final products. As a result, sustainable alternatives are in demand to mitigate the prevailing issues for both conventional and organic farming. Potential alternatives may include bacteriophages, vaccination, probiotics, plant-derived prebiotics, and synbiotics. These alternatives have beneficial attributes and shortcomings of their use in both conventional and organic poultry production system. In this review, we'll discuss the scope of these potential alternatives as therapeutics and subtherapeutics in sustainable poultry production and ways to improve their efficacy.

Purified Plant-Derived Phenolic Acids Inhibit Salmonella Typhimurium without Alteration of Microbiota in a Simulated Chicken Cecum Condition

Salmonella enterica serovar Typhimurium (ST) remains a predominant zoonotic pathogen because of its colonization in poultry, survivability in the environment, and increasing antibiotic-resistance pattern. Plant-derived phenolics, gallic acid (GA), protocatechuic acid (PA), and vanillic acids (VA) have demonstrated antimicrobial activity in vitro; therefore, this study collected chicken cecal fluid and supplemented it with these phenolics to evaluate their potential for eliminating ST and mod-ulating the microbiota of complex environments. ST was quantified through plating, while micro-biome analysis was performed through pair-end 16S-rRNA gene sequencing. CFU/mL of ST in cecal fluid with GA was significantly reduced by 3.28 and 2.78 log at 24 h and 48 h, while PA only had a slight numerical decrease. VA significantly reduced ST by 4.81 and 5.20 log at 24 h and 48 h. Changes in relative abundance of major phyla were observed at 24 h for samples with GA and VA as Firmicute levels increased 8.30% and 20.90%, while Proteobacteria decreased 12.86% and 18.48%, respectively. Significant changes in major genre were observed in Acinetobacter (3.41% for GA) and Escherichia (13.53% for VA), while Bifidobacterium increased (3.44% for GA) and Lactobacillus remained unchanged. Results suggest that phenolic compounds exert different effects on certain pathogens, while supporting some commensal bacteria.

Compound probiotics can improve intestinal health by affecting the gut microbiota of broilers

Probiotics, as a widely used additive, have played a unique advantage in replacing antibiotic products. As a result, the probiotic effects on broiler development, intestinal flora, intestinal barrier, and immunity were assessed by this investigation. Four hundred and eighty 1-day-old Arbor Acres broilers were randomly allotted to 4 groups of 5 replicates with 24 broilers each. The control was fed only a basal corn-soybean meal diet. Probiotics I, probiotics II, and probiotics III were fed basal diet and 1, 5, and 10 g/kg compound probiotics (Lactobacillus casei: Lactobacillus acidophilus: Bifidobacterium = 1:1:2), respectively. We found that broilers in the compound probiotic group exhibited better growth performance and carcass characteristics compared with control, especially among probiotics III group. The intestinal barrier-related genes relative expression of Claudin, Occludin, MUC2, and ZO-1 mRNA in the probiotic group increased at 21 and 42 d compared with control, especially among probiotics III group (P < 0.05). The early gut immune-related genes (TLR2, TLR4, IL-1β, and IL-2) mRNA increased compared with control, while the trend at 42 d was completely opposite to that in the earlier stage (P < 0.05). Among them, probiotics III group showed the most significant changes compared to probiotics II group and probiotics I group. Select probiotics III group and control group for 16S rDNA amplicon sequencing analysis. The 16S rDNA amplicon sequencing results demonstrated that probiotics increased the relative abundance of beneficial microbes such as o_Bacteroidales, f_Rikenellaceae, and g_Alistipes and improved the cecum's gut microbiota of 42-day-old broilers. Additionally, adding the probiotics decreased the relative abundance of harmful microbes such as Proteobacteria. PICRUSt2 functional analysis revealed that most proteins were enriched in DNA replication, transcription, and glycolysis processes. Therefore, this study can provide theoretical reference value for probiotics to improve production performance, improve intestinal barrier, immunity, intestinal flora of broilers, and the application of probiotics.

Tofu Whey Wastewater as a Beneficial Supplement to Poultry Farming: Improving Production Performance and Protecting against Salmonella Infection

Tofu whey wastewater (TWW) is a by-product of the tofu production process, and contains high amounts of organic products and Lactobacillus ap. However, no studies have been reported on whether naturally fermented TWW can be used as a beneficial additive for poultry production. This study analyzed the main nutritional components and microbial flora of naturally fermented TWW from rural tofu processing plants and their effect on chick production performance, role in modulating the biochemical and immune parameters, and protection against Salmonella enteritidis (S. enteritidis) infection. It was observed that the average pH of TWW was 4.08; therefore, the total viable count was 3.00 × 10⁹ CFU/mL and the abundance of Lactobacillus was 92.50%. Moreover, TWW supplementation increased the total weight gain and feed intake, reduced the feed/gain ratio, increased the length and relative weight of the gut, and reduced the colonization and excretion of S. enteritidis in chickens. Additionally, TWW decreased oxidative damage and pro-inflammatory cytokine secretion caused by S. enteritidis infection. In addition, TWW supplementation ensured the structure of the intestine remained relatively intact in S. enteritidis-infected chicken. Furthermore, TWW markedly promoted the intestinal barrier integrity and up-regulated the relative abundance of Lactobacillus, counteracting the changes in gut microbiota caused by S. enteritidis infection in chicken. In conclusion, our data demonstrated that TWW could be used as a beneficial addition to poultry production, providing a research basis for the further development of TWW as a health care application in in food-producing animal.

In Vitro and In Vivo Evaluation of Lacticaseibacillus rhamnosus GG and Bifidobacterium lactis Bb12 Against Avian Pathogenic Escherichia coli and Identification of Novel Probiotic-Derived Bioactive Peptides

Avian pathogenic E. coli (APEC), an extra-intestinal pathogenic E. coli (ExPEC), causes colibacillosis in poultry and is also a potential foodborne zoonotic pathogen. Currently, APEC infections in poultry are controlled by antibiotic medication; however, the emergence of multi-drug-resistant APEC strains and increased restrictions on the use of antibiotics in food-producing animals necessitate the development of new antibiotic alternative therapies. Here, we tested the anti-APEC activity of multiple commensal and probiotic bacteria in an agar-well diffusion assay and identified Lacticaseibacillus rhamnosus GG and Bifidobacterium lactis Bb12 producing strong zone of inhibition against APEC. In co-culture assay, L. rhamnosus GG and B. lactis Bb12 completely inhibited the APEC growth by 24 h. Further investigation revealed that antibacterial product(s) in the culture supernatants of L. rhamnosus GG and B. lactis Bb12 were responsible for the anti-APEC activity. The analysis of culture supernatants using LC-MS/MS identified multiple novel bioactive peptides (VQAAQAGDTKPIEV, AFDNTDTSLDSTFKSA, VTDTSGKAGTTKISNV, and AESSDTNLVNAKAA) in addition to the production of lactic acid. The oral administration (10⁸ CFU/chicken) of L. rhamnosus GG significantly (P < 0.001) reduced the colonization (~ 1.6 logs) of APEC in the cecum of chickens. Cecal microbiota analysis revealed that L. rhamnosus GG moderated the APEC-induced alterations of the microbial community in the cecum of chickens. Further, L. rhamnosus GG decreased (P < 0.05) the abundance of phylum Proteobacteria, particularly those belonging to Enterobacteriaceae (Escherichia-Shigella) family. These studies indicate that L. rhamnosus GG is a promising probiotic to control APEC infections in chickens. Further studies are needed to optimize the delivery of L. rhamnosus GG in feed or water and in conditions simulating the field to facilitate its development for commercial applications.

Impact of Lactobacillus-originated metabolites on enterohemorrhagic E. coli in rumen fluid

Rumen is one of the richest microbial ecosystems naturally harboring many zoonotic pathogens. Controlling the colonization of cattle originated zoonotic pathogens in rumen, particularly enterohemorrhagic Escherichia coli (EHEC), is critical in reducing foodborne enteric diseases in humans. In this study, we aimed to inhibit the growth of EHEC in a simulated rumen system with collected rumen fluids (RFs) using live probiotics, synbiotics, and their metabolites. EHEC inoculated RF was treated with live wild type Lactobacillus casei (LCwt), LCwt with 0.5% peanut flour (LCwt+PF), an engineered LC capable of overexpressing linoleate isomerase (LCCLA), and their metabolites collected in cell-free culture supernatants (CFCSwt, CFCSwt+PF, and CFCSCLA) at various time points. A growth stimulatory effect toward Lactobacillus spp. was exerted by all CFCS, while the EHEC was suppressed. Among other treatments only LCwt+PF reduced EHEC by 2.68 logs after 72 h. This observation was also supported by metataxonomic analysis. A reduction in Bacteroidetes and Proteobacteria while increase in Firmicutes was observed at 48 h by the presence of CFCSs as compared to the control. Our observation implies probiotic-originated metabolites modulate rumen microbiota positively which can be deployed to control the transmission of cattle-borne pathogens specifically EHEC.

Metagenomic Insights into Chicken Gut Antibiotic Resistomes and Microbiomes

The chicken gut microbiota, as a reservoir of antibiotic resistance genes (ARGs), poses a high risk to humans and animals worldwide. Yet a comprehensive exploration of the chicken gut antibiotic resistomes remains incomplete. In this study, we established the largest chicken gut resistance gene catalogue to date through metagenomic analysis of 629 chicken gut samples. We found significantly higher abundance of ARGs in the Chinese chicken gut than that in the Europe. tetX, mcr, and blaNDM, the genes resistant to antibiotics of last resort for human and animal health, were detected in the Chinese chicken gut. The abundance of ARGs was linearly correlated with that of mobile genetic elements (MGEs). The host-tracking analysis identified Escherichia, Enterococcus, Staphylococcus, Klebsiella, and Lactobacillus as the major ARG hosts. Especially, Lactobacillus, an intestinal probiotic, carried multiple drug resistance genes, and was proportional to ISLhe63, highlighting its potential risk in agricultural production processes. We first established a reference gene catalogue of chicken gut antibiotic resistomes. Our study helps to improve the knowledge and understanding of chicken antibiotic resistomes for knowledge-based sustainable chicken meat production. IMPORTANCE The prevalence of antibiotic resistance genes in the chicken gut environment poses a serious threat to human health; however, we lack a comprehensive exploration of antibiotic resistomes and microbiomes in the chicken gut environment. The results of this study demonstrate the diversity and abundance of antibiotic resistance genes and flora in the chicken gut environment and identify a variety of potential hosts carrying antibiotic resistance genes. Further analysis showed that mobile genetic elements were linearly correlated with antibiotic resistance genes abundance, implying that we should pay attention to the role played by mobile genetic elements in antibiotic resistance genes transmission. We established a reference genome of gut antibiotic resistance genes in chickens, which will help to rationalize the use of drugs in poultry farming.

Probiotics: Symbiotic Relationship with the Animal Host

Antibiotic growth-promoters in animal feeding are known to generate bacterial resistance on commercial farms and have proven deleterious effects on human health. This review addresses the effects of probiotics and their symbiotic relationship with the animal host as a viable alternative for producing healthy meat, eggs, and milk at present and in the future. Probiotics can tolerate the conditions of the gastrointestinal tract, such as the gastric acid, pH and bile salts, to exert beneficial effects on the host. They (probiotics) may also have a beneficial effect on productivity, health and wellbeing in different parameters of animal performance. Probiotics stimulate the native microbiota (microbes that are present in their place of origin) and production of short-chain fatty acids, with proven effects such as antimicrobial, hypocholesterolemic and immunomodulatory effects, resulting in better intestinal health, nutrient absorption capacity and productive responses in ruminant and non-ruminant animals. These beneficial effects of probiotics are specific to each microbial strain; therefore, the isolation and identification of beneficial microorganisms, as well as in vitro and in vivo testing in different categories of farm animals, will guarantee their efficacy, replicability and sustainability in the current production systems.

Innovative Treatments Enhancing the Functionality of Gut Microbiota to Improve Quality and Microbiological Safety of Foods of Animal Origin

The gastrointestinal tract, or gut, microbiota is a microbial community containing a variety of microorganisms colonizing throughout the gut that plays a crucial role in animal health, growth performance, and welfare. The gut microbiota is closely associated with the quality and microbiological safety of foods and food products originating from animals. The gut microbiota of the host can be modulated and enhanced in ways that improve the quality and safety of foods of animal origin. Probiotics—also known as direct-fed microbials—competitive exclusion cultures, prebiotics, and synbiotics have been utilized to achieve this goal. Reducing foodborne pathogen colonization in the gut prior to slaughter and enhancing the chemical, nutritional, or sensory characteristics of foods (e.g., meat, milk, and eggs) are two of many positive outcomes derived from the use of these competitive enhancement–based treatments in food-producing animals.

Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Influence of lincomycin-spectinomycin treatment on the outcome of Enterococcus cecorum infection and on the cecal microbiota in broilers

Background

Enterococcus cecorum (EC) is one of the main reasons for skeletal disease in meat type chickens. Intervention strategies are still rare and focus mainly on early antibiotic treatment of the disease, although there are no data available concerning the effectivity of this procedure. The present study aimed to investigate the effectivity of early lincomycin-spectinomycin treatment during the first week of life after EC-infection. Furthermore, the impact of lincomycin-spectinomycin treatment and EC infection on the development of cecal microbiota was investigated.

Methods

A total of 383 day-old broiler chicks were randomly assigned to four groups (non-infected and non-treated, non-infected and treated, EC-infected and non-treated, and EC-infected and treated). The EC-infected groups were inoculated orally with an EC suspension at the day of arrival and at study day 3. The treatment groups were treated with lincomycin-spectinomycin via the drinking water for six consecutive days, starting two hours after the first inoculation. Necropsy of 20 chickens per group was performed at study days 7, 14, 21, and 42. Bacteriological examination via culture and real-time PCR was performed to detect EC in different extraintestinal organs. Cecal samples of nine chickens per group and necropsy day were analyzed to characterize the composition of the cecal microbiota.

Results

No clinical signs or pathologic lesions were found at necropsy, and EC was not detected in extraintestinal organs of the EC-infected and treated birds. Lincomycin-spectinomycin promoted the growth of the bacterial genus Escherichia/Shigella and reduced the amount of potentially beneficial Lactobacillus spp. in the ceca regardless of EC-infection. Unexpectedly, the highest abundances of the genus Enterococcus were found directly after ending antibiotic treatment in both treatment groups, suggesting the growth of resistant enterococcal species. EC was not detected among the most abundant members of the genus Enterococcus. Oral EC-infection at the first day of life did not influence the development of cecal microbiota in the present study.

Conclusions

Lincomycin-spectinomycin treatment during the first week of life can prevent the EC-associated disease in broiler type chickens and has a direct impact on the development of the cecal microbiota. The low abundance of EC in the ceca of infected chickens underlines the pathogenic nature of the disease-causing EC strains. Further research on alternative prevention and intervention strategies is needed with regard to current efforts on reducing the use of antibiotics in livestock animals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13099-021-00467-9.

Onion leaf and synthetic additives in broiler diet: impact on splenic cytokines, serum immunoglobulins, cecal bacterial population, and muscle antioxidant status

BACKGROUND

The disadvantages associated with the use of synthetic additives in animal production could threaten human and animal health, and the safety of animal-derived foods. This study assessed the growth performance, blood chemistry, immune indices, selected caeca bacterial population, muscle antioxidant enzyme activities, and meat quality in broiler chickens fed diet supplemented with antibiotic (70% oxytetracycline +30% neomycin), tert-butylhydroxytoluene or onion leaf powder (OLP). One day old Ross 308 chicks (n = 240) were assigned randomly to either D-1, control diet (CD) without additives; D-2, CD + 0.3 g kg^-1 antibiotic +0.15 g kg^-1 tert-butylhydroxytoluene; D-3, CD + 2.5 g kg^-1 OLP; or D-4, CD + 5 g kg^-1 OLP for 42 days.

RESULTS

The D-2 and D-4 diets improved (P < 0.05) bodyweight gain and feed efficiency in broilers. Platelet and cecal Lactobacillus spp. counts were higher (P < 0.05) whereas muscle cholesterol was lower (P < 0.05) in the OLP-supplemented birds. Supplemented birds had higher (P < 0.01) splenic interleukin-10 and lower (P < 0.01) splenic tumor necrosis factor-α, immunoglobulin A, cecal E. coli and C. perfringens counts compared with the D-1 birds. The D-4 birds had the least (P < 0.05) splenic interleukin-1β. Dietary supplements increased (P < 0.05) catalase, glutathione peroxidase, and total antioxidant capacity, and lowered (P < 0.05) drip loss, malondialdehyde and carbonyl content in breast meat.

CONCLUSION

Dietary supplementation of 5 g kg^-1 OLP exerted antimicrobial, immunomodulatory, and antioxidant effects that were comparable to those of antibiotics and tert-butylhydroxytoluene in broiler chickens. © 2021 Society of Chemical Industry.

Functional enrichment of gut microbiome by early supplementation of Bacillus based probiotic in cage free hens: a field study

BACKGROUND

The chicken gut microbiota passes through different stages of maturation; therefore, strengthening it with well characterised probiotics increases its resilience required for optimum gut health and wellbeing. However, there is limited information on the interaction of Bacillus based probiotics with gut microbial community members in cage free laying chickens both in rearing and production phases of life. In the current study, we investigated the changes in the gut microbiome of free range hens in the field after Bacillus based probiotic supplementation.

RESULTS

Overall, at phylum level, probiotic supplementation increased the populations of Bacteroidetes and Proteobacteria mainly at the expense of Firmicutes. The population of Bacteroidetes significantly increased during the production as compared to the rearing phase, and its higher population in the probiotic-supplemented chickens reflects the positive role of Bacillus based probiotic in gut health. Core differences in the beta diversity suggest that probiotic supplementation decreased microbial compositionality. The non-significant difference in alpha diversity between the probiotic and control chickens showed that the composition of community structure did not change. No Salmonella spp. were isolated from the probiotic supplemented birds. Egg internal quality was significantly higher, while egg production and body weight did not differ. Functional prediction data showed that probiotic supplementation enriched metabolic pathways, such as vitamin B6 metabolism, phenylpropanoid biosynthesis, monobactam biosynthesis, RNA degradation, retinol metabolism, pantothenate and CoA biosynthesis, phosphonate and phosphinate metabolism, AMPK signaling pathway, cationic antimicrobial peptide (CAMP) resistance and tyrosine metabolism.

CONCLUSIONS

Overall, age was the main factor affecting the composition and diversity of gut microbiota, where probiotic supplementation improved the abundance of many useful candidates in the gut microbial communities. The generated baseline data in the current study highlights the importance of the continuous use of Bacillus based probiotic for optimum gut health and production.

Long-Term Grow-Out Affects Campylobacter jejuni Colonization Fitness in Coincidence With Altered Microbiota and Lipid Composition in the Cecum of Laying Hens

Campylobacter jejuni is one of the leading causes of gastrointestinal illness worldwide and is mainly transmitted from chicken through the food chain. Previous studies have provided increasing evidence that this pathogen can colonize and replicate in broiler chicken during its breeding; however, its temporal kinetics in laying hen are poorly understood. Considering the possible interaction between C. jejuni and gut microbiota, the current study was conducted to address the temporal dynamics of C. jejuni in the cecum of laying hen over 40 weeks, with possible alteration of the gut microbiota and fatty acid (FA) components. Following oral infection with C. jejuni 81-176, inocula were stably recovered from ceca for up to 8 weeks post-infection (p.i.). From 16 weeks p.i., most birds became negative for C. jejuni and remained negative up to 40 weeks p.i. 16S rRNA gene sequencing analyses revealed that most of the altered relative rRNA gene abundances occurred in the order Clostridiales, in which increased relative rRNA gene abundances were observed at >16 weeks p.i. in the families Clostridiaceae, Ruminococcaceae, Lachnospiraceae, and Peptococcaceae. Lipidome analyses revealed increased levels of sterols associated with bile acid metabolisms in the cecum at 16 and/or 24 weeks p.i. compared with those detected at 8 weeks p.i., suggesting that altered microbiota and bile acid metabolism might underlie the decreased colonization fitness of C. jejuni in the gut of laying hens.

Lactobacillus casei protects intestinal mucosa from damage in chicks caused by Salmonella pullorum via regulating immunity and the Wnt signaling pathway and maintaining the abundance of gut microbiota

Dysfunction of the intestinal mucosal barrier of chicks caused by Salmonella pullorum is of great harm to the poultry industry. Probiotics are recognized for their beneficial health-promoting properties, promoting maintenance of bowel epithelial integrity and host immune system homeostasis. Our previous research showed that Lactobacillus casei protects jejunal mucosa from injury in chicks infected with S. pullorum. However, the specific mechanisms underlying its protective properties are still not fully understood. In the present study, we aimed to explore the mechanisms underlying the protective effects of L. casei on the intestinal mucosal barrier of chicks infected with S. pullorum through histological, immunological, and molecular biology methods. The results indicated that L. casei significantly reduced the diarrhea rate, increased the daily weight gain, and maintained normal levels of IgA, IgM, and IgG in the serum of chicks infected with S. pullorum. Furthermore, we found that L. casei markedly improved the immunity of gut mucosa by regulating cytokine and chemokine receptor balance, elevating the number of intraepithelial lymphocytes, and hence effectively restraining bowel inflammation. Strikingly, feeding of infected chicks with L. casei notably boosted interleukin-22 expression to activate the Wingless-Int pathway, moderated diamine oxidase and D-lactic acid levels, diminished the generation of myosin light chain kinase, and expanded tight junction protein levels (Zonulin-1 and Claudin-1), strengthening the function of the gut mucosal epithelium. In addition, experiments using 16S rDNA sequencing also demonstrated that L. casei immensely weakened the adhesion of S. pullorum, mainly manifesting as improved diversity of the intestinal microbiota in the V4 area of infected chicks. Taken together, these results show that the application of L. casei may be a good strategy to regulate the intestinal inflammatory response of chicks infected with S. pullorum, providing new perspectives in producing antibiotic substitutes in poultry farms.

Probiotic Properties and Immunomodulatory Activity of Lactobacillus Strains Isolated from Dairy Products

Lactobacilli species are an effective biotherapeutic alternative against bacterial infections and intestinal inflammatory disorders. However, it is important to evaluate their beneficial properties, before considering them as probiotics for medical use. In this study we evaluated some probiotic properties of Lactobacillus rhamnosus GG, Lactobacillus rhamnosus KLSD, Lactobacillus helveticus IMAU70129, and Lactobacillus casei IMAU60214 previously isolated from dairy products and as control Lactobacillus casei Shirota. Experimental evaluations revealed that all strains expressed hydrophobicity (25–40%), auto-aggregation (55–60%), NaCl tolerance (1–4%), adhesion to Caco-2 cells (25–33%), partial inhibition on adherence of Escherichia coli ATCC 35218, Salmonella Typhimurium ATCC 14028, and Staphylococcus aureus ATCC 23219. Cell-free supernatants (CFS) of Lactobacilli also inhibit growth of these pathogens. In immunomodulatory properties a reduction of interleukin-8 (IL-8) and nitric oxide (NO) release was observed in assays with Caco-2 cells stimulated with interleukin-1β (1 ng/mL), or lipopolysaccharide (0.1 µg/mL). On the other hand, the damage induced to Caco-2 cells with sodium dodecyl sulfate (SDS) was attenuated when the cultured cells were pretreated with L. rhamnosus KLDS, L. helveticus IMAU70129 and L. casei IMAU60214. These Lactobacilli possess probiotic properties determined by both an antagonistic activity on pathogenic bacteria and reduction in the inflammatory response of cells treated with SDS, a pro-inflammatory stimulant.