Molecules produced by probiotics prevent enteric colibacillosis in pigs

Understanding the Effect of Compound Probiotics on the Health of Rabbits and Its Mechanisms Through Metagenomics

In this study, we investigated the effects of probiotics on growth performance, immunity, intestinal flora, and antioxidant capacity of rabbits. Three hundred New Zealand white rabbits were randomly divided into four groups. Groups A, B, C, and D were the lactobacillus group, compound probiotic group, control group, and antibiotic group, respectively. The results showed compared with the control group, the average weight of groups A, B, and D increased by 14.88%, 12.33%, and 11.97%, respectively. Moreover, the index of immune organs and the IgG and IgM in serum of group B were significantly increased (P < 0.05). Meanwhile, the activities of superoxide dismutase (SOD) in group B and catalase (CAT) in group A were significantly increased (P < 0.05). At week 5, the contents of rabbit cecum were taken for metagenome sequencing, and the results showed probiotics increased the relative abundance of Akkermansia, and decreased the relative abundance of Bacteroides. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, we found probiotics could enrich metabolic pathways such as carbohydrates, amino acids, and lipids. According to the Comprehensive Antibiotic Resistance Database (CARD), we found antibiotic resistance ontology (ARO) in cecum mainly included β-lactamases, macrolide 2'-phosphotransferase II, and plasmid-mediated quinolone resistance protein. Among them, there were 1964, 2105, and 1982 types of ARO in group B, group D, and groups A and C, respectively. These results showed probiotics played a beneficial role in maintaining or enhancing the health and growth of rabbits and could replace antibiotics under certain feeding conditions.

Beyond probiotics, uses of their next-generation for poultry and humans: A review

The production of healthy food is one of the basic requirements and challenges. Research efforts have been introduced in the human's food industry to reduce the microbial resistance and use safe and healthy alternatives with a high durability. However, the conducted work about these issues in the field of livestock animal production have been started since 2015. Inappropriate and extensive use of antibiotics has resulted in the increase of antimicrobial resistance, presence of drug residues in tissues, and destruction of the gut microbiome. Therefore, discovering and developing antibiotic substitutes were urgent demands. Probiotic compounds containing living micro-organisms are important antibiotic alternative that have been beneficially and extensively used in humans, animals, and poultry. However, some probiotics show some obstacles during production and applications. Accordingly, this review article proposes a comprehensive description of the next-generation of probiotics including postbiotics, proteobiotics, psychobiotics, immunobiotics and paraprobiotics and their effects on poultry production and human's therapy. These compounds proved great efficiency in terms of restoring gut health, improving performance and general health conditions, modulating the immune response and reducing the pathogenic micro-organisms. However, more future research work should be carried out regarding this issue.

Effect of a Lactococcus lactis culture supernatant on diarrhea and performance parameters of piglets in the post-weaning period and on expression of the faeG gene in vitro

Objectives

To evaluate the effects of a cell-free supernatant from Lactococcus lactis (CFSM) on performance and diarrhearelated parameters and the presence of F4+ enterotoxigenic E. coli (ETEC) in piglets during post-weaning, and to evaluate the in vitro effect of the CFSM on faeG gene expression in an E. coli F4+.

Animals and procedure

In 3 trials with 90 piglets per trial, pigs were assigned to receive a placebo or 1 of 2 CFSM treatments and observed for diarrhea and performance. Fecal swabs were taken to determine the presence of ETEC. Quantitative RT-PCR was used to assess faeG gene expression in E. coli 21259 after treatment with CFSM at 50 mg/mL.

Results

The CFSM administered for 14 d at a dose of 24 mg/kg BW (2X) reduced diarrhea-related parameters compared to the placebo. Quantitative RT-PCR showed that, in E. coli 21259 treated with CFSM at 50 mg/mL, expression of the faeG gene was significantly repressed (P < 0.0001) relative to that in the untreated control.

Conclusion

The evaluated CFSM reduced the frequency and prevalence of diarrhea in a field situation. The in vitro treatment had an inhibitory effect on the expression of the faeG gene in F4+ E. coli 21259.

Evaluation of a Lactococcus lactis-based dried fermentation product administered through drinking water on nursery pig growth performance, fecal Escherichia coli virulence genes and pathotypes, antibiotic usage, and mortality

A total of 34,749 pigs were used in two experiments to evaluate the effects of a postbiotic dried fermentation product (DFP) administered through drinking water on nursery pig growth performance, antibiotic injection frequency, morbidity, mortality, fecal consistency, and characterization of fecal Escherichia coli. The DFP is composed of bioactive molecules derived from Lactococcus lactis. In Exp. 1, 350 barrows (DNA Line 200 × 400; initial body weight [BW] 6.1 ± 0.01 kg) were used in a 42-d study with five pigs per pen and 35 pens per treatment. The DFP was supplied for 14 d at a target dosage of 24 mg/kg BW using a water medicator at a 1:128 dilution. On days 7 and 14, fecal samples were collected for dry matter (DM) and to determine, by a multiplex polymerase chain reaction (PCR) assay, prevalence of 11 virulence genes characteristic of E. coli pathotypes. There was no evidence (P > 0.10) for differences for growth, incidence of diarrhea, number of antibiotic injections, removals, or fecal DM. On both fecal collection days, E. coli virulence genes were present with day 7 samples positive for genes that encode for hemolysins (hlyA, exhA), intimin (eae), and enteroaggregative heat-stable enterotoxin (astA). Prevalence of enterotoxin genes (elt, estA, estB, astA) increased on day 14, but DFP had no effects on the prevalence of any of the virulence genes. A total of 32 out of 72 E. coli isolates were identified as enterotoxigenic pathotype and all except one were from day 14 fecal samples. Fourteen isolates were positive for F4 fimbria and one isolate was positive for F4 and F18 fimbriae. In Exp. 2, 34,399 nursery pigs (initially 5.6 kg) were used in 20 nursery barns with 10 barns per treatment (control or DFP). The target dosage of the DFP for the first 14 d was 35 mg/kg BW. Following the 14-d supplementation period, pigs continued to be monitored for approximately 31 d. There was no evidence (P > 0.05) for the DFP to influence the overall percentage of pigs that died or growth performance. From days 0 to 14, providing the DFP reduced (P < 0.05) the percentage of pigs that were euthanized. However, providing the DFP increased (P < 0.05) the overall percentage of pigs that were euthanized and total mortality. For the number of antibiotic injections (treatment interventions), providing the DFP reduced the number of injections for the common period (P < 0.001) and overall (P = 0.002). These results indicate that the DFP did not influence growth performance but providing the DFP in Exp. 2 led to increased total nursery pig mortality.

One Health challenges for pig reproduction

The current state of the world challenges pig reproduction as an important part of One Health, which involves interrelationships between animal, human and environmental health. The One Health concept underlines a comparative aspect in reproductive physiology and disease occurrence, bridging knowledge from one species to another. Seasonal changes in the environment affect pig reproduction and climate change may further strengthen those effects. Endocrine-disrupting chemicals (EDCs), and specifically phthalates and heavy metals, interfere with endocrine function, and thereby sexual behavior, fertilization capacity and steroidogenesis. Reproductive infections and extended semen storage are important indications for antimicrobial use. Innovative solutions are needed to explore alternatives to antimicrobials. Efforts to ensure reproductive efficiency have prolonged farrowing as litter size has doubled over the past three decades, compromising immune transfer and welfare. Physiological, metabolic and programming related events around parturition are key areas for future One Health research in pig reproduction. In conclusion, climate change challenges reproductive management and breeding. More resilient pigs that can tolerate harsh environment but maintain high reproductive performance are needed. EDCs continue to grow as an environmental challenge for reproductive management and alternatives to antibiotics will be required.

Risk factors associated with post-weaning diarrhoea in Austrian piglet-producing farms

Post-weaning diarrhoea (PWD) is a frequent, multifactorial disease of piglets leading to increased mortality rates and high economic losses. Due to the emergence of multi-resistant Escherichia coli isolates and the ban of zinc oxide (ZnO) in the EU since June 2022, alternative measures to prevent PWD are urgently needed. While an abundance of feed supplements is described to prevent PWD, there are hardly any studies reflecting the current situation of PWD in the field. Thus, we aimed to identify differences in management practices, housing and feeding strategies between farms with PWD and farms without PWD. Data were personally collected using a semi-structured questionnaire in 257 Austrian piglet-producing farms. Farms with PWD in more than 10% of all weaned groups within twelve months prior to data collection were defined as case farms (n = 101), while the remaining 136 farms were defined as control farms. Data from 237 farms and 69 explanatory variables were analysed via penalized binary logistic regression using elastic-net in 100 different splits into randomly selected training and test datasets (80:20). Treatment with ZnO and/or colistin (136 farms) was negatively associated with PWD in all splits and had the biggest estimated absolute log odds ratio out of all tested variables. Implementation of an all-in/all-out system in the nursery units and administration of probiotics or horseradish also had preventive effects in most splits (≥ 97%). A higher number of feeding phases for piglets within the first seven weeks of life and housing on fully slatted floors was associated negatively with the occurrence of PWD as well in > 95% of all splits. PWD was more likely to occur on farms having problems with neonatal diarrhoea or postpartum dysgalactia syndrome. While our data demonstrate that treatment with ZnO or colistin had the biggest statistical effect on PWD, we were able to identify other preventive measures like supplementation with probiotics or horseradish. Since implementation of all-in/all-out measures and fully slatted floors were also negatively associated with the occurrence of PWD on visited farms, we assume that reduction of bacterial load by the implementation of simple hygiene measures are still crucial to prevent PWD.

Development of an In Vivo Extended-Spectrum Cephalosporin-Resistant Escherichia coli Model in Post-Weaned Pigs and Its Use in Assessment of Dietary Interventions

Current interventions targeting antimicrobial resistance (AMR), a major impact on commercial pork production, focus on reducing the emergence of AMR by minimising antimicrobial usage through antimicrobial stewardship and a range of alternative control methods. Although these strategies require continued advancement, strategies that directly aim to reduce or eliminate existing antimicrobial resistant bacteria, specifically bacteria resistant to critically important antimicrobials (CIAs), need to be investigated and established. This study established an in vivo model for examining the effects of postbiotics, in the form of Lactobacillus acidophilus fermentation products (LFP) and Saccharomyces cerevisiae fermentation products (SFP), on the shedding of extended-spectrum cephalosporin (ESC)-resistant E. coli. The model was successful in demonstrating the presence of ESC-resistant E. coli as evidenced by its detection in 62 of 64 pigs. There was a strong trend (p = 0.065) for the SFP postbiotics to reduce the shedding of ESC-resistant E. coli, indicating positive impacts of this additive on reducing the carriage of bacteria resistant to CIAs. Overall, this in vivo model enables future evaluation of strategies targeting ESC-resistant E. coli while increasing our knowledge on the carriage of ESC-resistant E. coli in pigs.

Review on Preventive Measures to Reduce Post-Weaning Diarrhoea in Piglets

In many countries, medical levels of zinc (typically as zinc oxide) are added to piglet diets in the first two weeks post-weaning to prevent the development of post-weaning diarrhoea (PWD). However, high levels of zinc constitute an environmental polluting agent, and may contribute to the development and/or maintenance of antimicrobial resistance (AMR) among bacteria. Consequently, the EU banned administering medical levels of zinc in pig diets as of June 2022. However, this may result in an increased use of antibiotic therapeutics to combat PWD and thereby an increased risk of further AMR development. The search for alternative measures against PWD with a minimum use of antibiotics and in the absence of medical levels of zinc has therefore been intensified over recent years, and feed-related measures, including feed ingredients, feed additives, and feeding strategies, are being intensively investigated. Furthermore, management strategies have been developed and are undoubtedly relevant; however, these will not be addressed in this review. Here, feed measures (and vaccines) are addressed, these being probiotics, prebiotics, synbiotics, postbiotics, proteobiotics, plants and plant extracts (in particular essential oils and tannins), macroalgae (particularly macroalgae-derived polysaccharides), dietary fibre, antimicrobial peptides, specific amino acids, dietary fatty acids, milk replacers, milk components, creep feed, vaccines, bacteriophages, and single-domain antibodies (nanobodies). The list covers measures with a rather long history and others that require significant development before their eventual use can be extended. To assess the potential of feed-related measures in combating PWD, the literature reviewed here has focused on studies reporting parameters of PWD (i.e., faeces score and/or faeces dry matter content during the first two weeks post-weaning). Although the impact on PWD (or related parameters) of the investigated measures may often be inconsistent, many studies do report positive effects. However, several studies have shown that control pigs do not suffer from diarrhoea, making it difficult to evaluate the biological and practical relevance of these improvements. From the reviewed literature, it is not possible to rank the efficacy of the various measures, and the efficacy most probably depends on a range of factors related to animal genetics and health status, additive doses used, composition of the feed, etc. We conclude that a combination of various measures is probably most recommendable in most situations. However, in this respect, it should be considered that combining strategies may lead to additive (e.g., synbiotics), synergistic (e.g., plant materials), or antagonistic (e.g., algae compounds) effects, requiring detailed knowledge on the modes of action in order to design effective strategies.

Postbiotics as potential new therapeutic agents for metabolic disorders management

The prevalence of obesity, diabetes, non-alcoholic fatty liver disease, and related metabolic disorders has been steadily increasing in the past few decades. Apart from the establishment of caloric restrictions in combination with improved physical activity, there are no effective pharmacological treatments for most metabolic disorders. Many scientific-studies have described various beneficial effects of probiotics in regulating metabolism but others questioned their effectiveness and safety. Postbiotics are defined as preparation of inanimate microorganisms, and/or their components, which determine their safety of use and confers a health benefit to the host. Additionally, unlike probiotics postbiotics do not require stringent production/storage conditions. Recently, many lines of evidence demonstrated that postbiotics may be beneficial in metabolic disorders management via several potential effects including anti-inflammatory, antibacterial, immunomodulatory, anti-carcinogenic, antioxidant, antihypertensive, anti-proliferative, and hypocholesterolaemia properties that enhance both the immune system and intestinal barrier functions by acting directly on specific tissues of the intestinal epithelium, but also on various organs or tissues. In view of the many reports that demonstrated the high biological activity and safety of postbiotics, we summarized in the present review the current findings reporting the beneficial effects of various probiotics derivatives for the management of metabolic disorders and related alterations.

Biological sex: an understudied factor driving disease susceptibility in pigs

Biological sex is a major host factor influencing risk for infectious disease-associated mortality, and chronic inflammatory and metabolic diseases. Research in human and rodent models -has revealed sex differences that exist across organ systems during health and disease that may contribute to sex biases in disease risk. Despite the robust and growing literature on the role of sex as a risk factor in human disease, comparatively little attention has been focused on investigating the role of biological sex in disease susceptibility in agriculturally important animal populations such as the pig. To date, comparisons between sexes have focused on carcass composition, growth rate, and feed efficiency in pigs. However, there is a large gap in the literature regarding the effects of biological sex on other integral aspects of health and disease. The objective of this review is to highlight the available literature reporting sex differences in pig health and biology with an emphasis on sex differences in mortality, immunity, and gastrointestinal (GI) physiology and to address biological sex as a significant biological variable in disease risk and research study design. A basic overview of the biology of sex differences including the major hormonal and genetic/chromosomal mechanisms of sexual differentiation and the developmental periods in which sex differences emerge will be covered. This review will also discuss how production-relevant management and environmental factors (e.g., wean age, castration, stress, and nutrition) interact with biological sex to shape host immune and GI development and function. Perceived gaps in knowledge and areas of future research will also be discussed.

In silico, in vitro and in vivo safety evaluation of Limosilactobacillus reuteri strains ATCC PTA-126787 & ATCC PTA-126788 for potential probiotic applications

The last two decades have witnessed a tremendous growth in probiotics and in the numbers of publications on their potential health benefits. Owing to their distinguishing beneficial effects and long history of safe use, species belonging to the Lactobacillus genus are among the most widely used probiotic species in human food and dietary supplements and are finding increased use in animal feed. Here, we isolated, identified, and evaluated the safety of two novel Limosilactobacillus reuteri (L. reuteri) isolates, ATCC PTA-126787 & ATCC PTA-126788. More specifically, we sequenced the genomes of these two L. reuteri strains using the PacBio sequencing platform. Using a combination of biochemical and genetic methods, we identified the two strains as belonging to L. reuteri species. Detailed in silico analyses showed that the two strains do not encode for any known genetic sequences of concern for human or animal health. In vitro assays confirmed that the strains are susceptible to clinically relevant antibiotics and do not produce potentially harmful by-products such as biogenic amines. In vitro bile and acid tolerance studies demonstrated that the two strains have similar survival profiles as the commercial L. reuteri probiotic strain DSM 17938. Most importantly, daily administration of the two probiotic strains to broiler chickens in drinking water for 26 days did not induce any adverse effect, clinical disease, or histopathological lesions, supporting the safety of the strains in an in vivo avian model. All together, these data provide in silico, in vitro and in vivo evidence of the safety of the two novel candidates for potential probiotic applications in humans as well as animals.

Antibiotic Resistance: From Pig to Meat

Pork meat is in high demand worldwide and this is expected to increase. Pork is often raised in intensive conditions, which is conducive to the spread of infectious diseases. Vaccines, antibiotics, and other biosafety measures help mitigate the impact of infectious diseases. However, bacterial strains resistant to antibiotics are more and more frequently found in pig farms, animals, and the environment. It is now recognized that a holistic perspective is needed to sustainably fight antibiotic resistance, and that an integrated One Health approach is essential. With this in mind, this review tackles antibiotic resistance throughout the pork raising process, including their microbiome; many factors of their environment (agricultural workers, farms, rivers, etc.); and an overview of the impact of antibiotic resistance on pork meat, which is the end product available to consumers. Antibiotic resistance, while a natural process, is a public health concern. If we react, and act, collectively, it is expected to be, at least partially, reversible with judicious antibiotic usage and the development of innovative strategies and tools to foster animal health.

W27 IgA suppresses growth of Escherichia in an in vitro model of the human intestinal microbiota

W27 monoclonal immunoglobulin A (IgA) suppresses pathogenic Escherichia coli cell growth; however, its effect on the human intestine remains unclear. We aimed to determine how W27 IgA affects the human colonic microbiota using the in vitro microbiota model. This model was established using fecal samples collected from 12 healthy volunteers; after anaerobic cultivation, each model was found to retain the genera found in the original human fecal samples. After pre-incubating W27 IgA with the respective fecal sample under aerobic conditions, the mixture of W27 IgA (final concentration, 0.5 μg/mL) and each fecal sample was added to the in vitro microbiota model and cultured under anaerobic conditions. Next-generation sequencing of the bacterial 16S rRNA gene revealed that W27 IgA significantly decreased the relative abundance of bacteria related to the genus Escherichia in the model. Additionally, at a final concentration of 5 μg/mL, W27 IgA delayed growth in the pure culture of Escherichia coli isolated from human fecal samples. Our study thus revealed the suppressive effect of W27 IgA on the genus Escherichia at relatively low-concentrations and the usefulness of an in vitro microbiota model to evaluate the effect of IgA as a gut microbiota regulator.

Screening of Lactic Acid Bacteria with Inhibitory Activity against ETEC K88 as Feed Additive and the Effects on Sows and Piglets

Simple Summary

Numerous reports have suggested that lactic acid bacteria (LAB), which are important probiotics, can protect animals against pathogen-induced injury and inflammation, regulate gut microflora, enhance digestive tract function, improve animal growth performance, and decrease the incidence of diarrhea caused by enterotoxigenic (ETEC) that expresses K88. This research selected Lactobacillus (L.) reuteri P7, L. amylovorus P8, and L. johnsonii P15 with good inhibition against ETEC K88 and excellent probiotic properties screened from 295 LAB strains isolated from fecal samples from 55 healthy weaned piglets for a study on feeding of sows in late pregnancy and weaned piglets. Feed supplementation with these three strains improved reproductive performance of sows and growth performance of piglets, decreased the incidence of diarrhea in piglets, and increased the antioxidant capacity of serum in both sows and piglets. Therefore, L. reuteri P7, L. amylovorus P8, and L. johnsonii P15 might be considered as potential antibiotic alternatives for further study.

Abstract

Enterotoxigenic Escherichia coli (ETEC), which expresses K88 is the principal microorganism responsible for bacterial diarrhea in pig husbandry, and the indiscriminate use of antibiotics has caused many problems; therefore, antibiotics need to be replaced in order to prevent diarrhea caused by ETEC K88. The objective of this study was to screen excellent lactic acid bacteria (LAB) strains that inhibit ETEC K88 and explore their effects as probiotic supplementation on reproduction, growth performance, diarrheal incidence, and antioxidant capacity of serum in sows and weaned piglets. Three LAB strains, P7, P8, and P15, screened from 295 LAB strains and assigned to Lactobacillus (L.) reuteri, L. amylovorus, and L. johnsonii with high inhibitory activity against ETEC K88 were selected for a study on feeding of sows and weaned piglets. These strains were chosen for their good physiological and biochemical characteristics, excellent exopolysaccharide (EPS) production capacity, hydrophobicity, auto-aggregation ability, survival in gastrointestinal (GI) fluids, lack of hemolytic activity, and broad-spectrum activity against a wide range of microorganisms. The results indicate that LAB strains P7, P8, and P15 had significant effects on improving the reproductive performance of sows and the growth performance of weaned piglets, increasing the activity of antioxidant enzymes and immune indexes in both.

Porcine enterotoxigenic Escherichia coli: Antimicrobial resistance and development of microbial-based alternative control strategies

Strains of enterotoxigenic Escherichia coli (ETEC) causing post-weaning diarrhoea (PWD) in piglets have a widespread and detrimental impact on animal health and the economics of pork production. Traditional approaches to control and prevention have placed a strong emphasis on antimicrobial use (AMU) to the extent that current prevalent porcine ETEC strains have developed moderate to severe resistance. This complicates treatment of ETEC infection by limiting therapeutic options, increasing diagnostic costs and increasing mortality rates. Management factors, the use of supra-physiological levels of zinc oxide and selected feed additives have all been documented to lower the incidence of ETEC infection in pigs; however, each intervention has its own limitations and cannot solely be relied upon as an alternative to AMU. Consequently, treatment options for porcine ETEC are moving towards the use of newer antimicrobials of higher public health significance. This review focuses on microorganisms and microbial-derived products that could provide a naturally evolved solution to ETEC infection and disease. This category holds a plethora of yet to be explored possibilities, however studies based around bacteriophage therapy, probiotics and the use of probiotic fermentation products as postbiotics have demonstrated promise. Ultimately, pig producers and veterinarians need these solutions to reduce the reliance on critically important antimicrobials (CIAs), to improve economic and animal welfare outcomes, and to lessen the One Health threat potentiated by the dissemination of AMR through the food chain.

Towards Zero Zinc Oxide: Feeding Strategies to Manage Post-Weaning Diarrhea in Piglets

Simple Summary

Zinc oxide (ZnO) supplementation at pharmacological doses in post-weaning piglets is a consolidated practice that allows efficient control of post-weaning diarrhea (PWD), a condition exacerbated by Escherichia coli F4 (K88) infections. Far from being completely elucidated, the multifactorial ZnO mechanism of action is in all likelihood exerted at the gastrointestinal level. However, increasing environmental concerns are arising from prolonged ZnO use. This article reviews the utilization of ZnO in piglets, the biological rationale behind its powerful activity, and the emerging threats that are leading towards a significant reduction in its use. Finally, a wide analysis of the strengths and weaknesses of innovative alternative strategies to manage PWD at the nutritional level is given.

Abstract

Zinc oxide (ZnO) at pharmacological doses is extensively employed in the pig industry as an effective tool to manage post-weaning diarrhea (PWD), a condition that causes huge economic losses because of its impact on the most pivotal phase of a piglet’s production cycle. In a multifactorial way, ZnO exerts a variety of positive effects along the entire gastrointestinal tract by targeting intestinal architecture, digestive secretions, antioxidant systems, and immune cells. ZnO also has a moderate antibacterial effect against Escherichia coli F4 (K88), the main causative agent of PWD. However, the environmental impact of ZnO and new emerging threats are posing serious questions to the sustainability of its extensive utilization. To work towards a future free from pharmacological ZnO, novel nutritional approaches are necessary, and many strategies have been investigated. This review article provides a comprehensive framework for ZnO utilization and its broad mode of action. Moreover, all the risks related to pharmacological ZnO levels are presented; we focus on European institutions’ decisions subsequently. The identification of a novel, complete solution against PWD should be accompanied by the adoption of holistic strategies, thereby combining good management practices to feeding approaches capable of mitigating Escherichia coli F4 (K88) infections and/or lowering ZnO utilization. Promising results can be obtained by adjusting diet composition or employing organic acids, natural identical compounds, polyphenol-rich extracts, prebiotics, and probiotics.

The alga Euglena gracilis stimulates Faecalibacterium in the gut and contributes to increased defecation

The alga Euglena gracilis (E. gracilis) has recently gained attention as a health food, but its effects on human gut microbiota remain unknown. This study aimed to determine the effect of E. gracilis on gut microbiota and defecation due to modulation of microbiota composition in vitro and in vivo. The in vitro model simulating human colonic microbiota revealed that E. gracilis addition stimulated the growth of commensal Faecalibacterium. Further, E. gracilis addition enhanced butyrate production by Faecalibacterium prausnitzii. Paramylon, an insoluble dietary fibre that accumulates in E. gracilis and is the main component of E. gracilis, did not stimulate Faecalibacterium growth in vitro. Daily ingestion of 2 g of E. gracilis for 30 days increased bowel movement frequency as well as stool volume in 28 human participants. Collectively, these findings indicate that E. gracilis components other than paramylon, stimulate the growth of Faecalibacterium to improve digestive health as well as promote defecation by increasing butyrate production.

Enhanced methane production from cellulose using a two-stage process involving a bioelectrochemical system and a fixed film reactor

BACKGROUND

It is desirable to improve the anaerobic digestion processes of recalcitrant materials, such as cellulose. Enhancement of methane (CH₄) production from organic molecules was previously accomplished through coupling a bioelectrochemical system (BES); however, scaling-up BES-based production is difficult. Here, we developed a two-stage process consisting of a BES using low-cost and low-reactive carbon sheets as the cathode and anode, and a fixed film reactor (FFR) containing conductive material, i.e., carbon fiber textiles (CFTs) (:BES → FFR). By controlling the cathodic current at 2.7 μA/cm² without abiotic H₂ production, the three-electrode BES system was operated to mimic a microbial electrolysis cell.

RESULTS

The thermophilic BES (inlet pH: 6.1) and FFR (inlet pH: 7.5) were operated using hydraulic retention times (HRTs) of 2.5 and 4.2 days, respectively, corresponding to a cellulose load of 3555.6 mg-carbon (C)/(L day). The BES → FFR process achieved a higher CH₄ yield (37.5%) with 52.8 vol% CH₄ in the product gas compared to the non-bioelectrochemical system (NBES) → FFR process, which showed a CH₄ yield of 22.1% with 46.8 vol% CH₄. The CH₄ production rate (67.5 mM/day) obtained with the BER → FFR process was much higher than that obtained using electrochemical methanogenesis (0.27 mM/day). Application of the electrochemical system or CFTs improved the yields of CH₄ with the NBES → FFR or BES → non-fixed film reactor process, respectively. Meta 16S rRNA sequencing revealed that putative cellulolytic bacteria (identified as Clostridium species) were present in the BES and NBES, and followed (BES→ and NBES→) FFR. Notably, H₂-consuming methanogens, Methanobacterium sp. and Methanosarcina sp., showed increased relative abundances in the suspended fraction and attached fraction of (BES→) FFR, respectively, compared to that of (NBES→) FFR, although these methanogens were observed at trace levels in the BES and NBES.

CONCLUSIONS

These results indicate that bioelectrochemical preprocessing at a low current effectively induces interspecies H₂ transfer in the FFR with conductive material. Sufficient electrochemical preprocessing was observed using a relatively short HRT. This type of two-stage process, BES → FFR, is useful for stabilization and improvement of the biogas (CH₄) production from cellulosic material, and our results imply that the two-stage system developed here may be useful with other recalcitrant materials.

Distribution of Important Probiotic Genes and Identification of the Biogenic Amines Produced by Lactobacillus acidophilus PNW3

The genome of Lactobacillus acidophilus PNW3 was assessed for probiotic and safety potentials. The genome was completely sequenced, assembled using SPAdes, and thereafter annotated with NCBI prokaryotic genome annotation pipeline (PGAP) and rapid annotation using subsystem technology (RAST). Further downstream assessment was determined using appropriate bioinformatics tools. The production of biogenic amines was confirmed through HPLC analysis and the evolutionary trend of the strain was determined through the Codon Tree pipeline. The strain was predicted as a non-human pathogen. A plethora of encoding genes for lactic acids and bioactive peptides production, adhesion molecules, resistance to the harsh gut environmental conditions, and improvement of the host metabolism, which are putative for important probiotic functionalities, were located at different loci within the genome. A bacteriocin predicted to be helveticin J was identified as one of the secondary metabolites. The maximum zone of inhibition exhibited by the crude bacteriocin against STEC E. coli O177 was 21.7 ± 0.58 mm and 24.3 ± 1.15 mm after partial purification (250 µg/mL). Three coding sequences were identified for insertion sequences and one for the CRISPR-Cas fragment. The protein-encoding sequence for Ornithine decarboxylase was found within the genome. L. acidophilus PNW3 presents important features categorizing it as a viable and safe probiotic candidate, though further safety investigations are necessary. The application of probiotics in livestock-keeping would ensure improved public health and food security.

State-of-the-Art of the Nutritional Alternatives to the Use of Antibiotics in Humans and Monogastric Animals

Simple Summary

Antibiotic resistance represents a worldwide recognized issue affecting both human and veterinary medicine, with a particular focus being directed towards monogastric animals destined for human consumption. This scenario is the result of frequent utilization of the antibiotics either for therapeutic purposes (humans and animals) or as growth promoters (farmed animals). Therefore, the search for nutritional alternatives has progressively been the object of significant efforts by the scientific community. So far, probiotics, prebiotics and postbiotics are considered the most promising products, as they are capable of preventing or treating gastrointestinal diseases as well as restoring a eubiosis condition after antibiotic-induced dysbiosis development. This review provides an updated state-of-the-art of these nutritional alternatives in both humans and monogastric animals.

Abstract

In recent years, the indiscriminate use of antibiotics has been perpetrated across human medicine, animals destined for zootechnical productions and companion animals. Apart from increasing the resistance rate of numerous microorganisms and generating multi-drug resistance (MDR), the nonrational administration of antibiotics causes sudden changes in the structure of the intestinal microbiota such as dysbiotic phenomena that can have a great clinical significance for both humans and animals. The aim of this review is to describe the state-of-the-art of alternative therapies to the use of antibiotics and their effectiveness in humans and monogastric animals (poultry, pigs, fish, rabbits, dogs and cats). In particular, those molecules (probiotics, prebiotics and postbiotics) which have a direct function on the gastrointestinal health are herein critically analysed in the prevention or treatment of gastrointestinal diseases or dysbiosis induced by the consumption of antibiotics.

Postbiotics against Pathogens Commonly Involved in Pediatric Infectious Diseases

The Sustainable Development goals for 2020 included reducing all causes associated with infant and perinatal mortality in their priorities. The use of compounds with bioactive properties has been proposed as a therapeutic strategy due to their stimulating effect on the host's immune system. Additionally, biotherapeutic products such as postbiotics, tentatively defined as compounds produced during a fermentation process that support health and well-being, promote intestinal barrier integrity without posing considerable risks to children's health. Although this is a concept in development, there are increasing studies in the field of nutrition, chemistry, and health that aim to understand how postbiotics can help prevent different types of infections in priority populations such as minors under the age of five. The present review aims to describe the main mechanisms of action of postbiotics. In addition, it presents the available current evidence regarding the effects of postbiotics against pathogens commonly involved in pediatric infections. Postbiotics may constitute a safe alternative capable of modulating the cellular response and stimulating the host's humoral response.

Integrated genome-based probiotic relevance and safety evaluation of Lactobacillus reuteri PNW1

This study evaluates whole-genome sequence of Lactobacillus reuteri PNW1 and identifies its safety genes that may qualify it as a putative probiotic. It further extracted the bacteriocin produced by the strain and tested its effectiveness against pathogenic STEC E. coli O177. The genomic DNA was sequenced on illuminal Miseq instrument and the sequenced data was assessed for quality reads before assembled with SPAdes. The draft assembly was annotated with Prokaryotic Genome Annotation Pipeline (PGAP) and Rapid Annotations using Subsystems Technology (RAST). Further downstream analyses were carried out using appropriate bioinformatic tools. Production of biogenic amines was biochemically confirmed through HPLC analysis. The assembled genome was 2,430,215 bp long in 420 contigs with 39% G+C content. Among all known genes, putatively responsible for the production of toxic biochemicals, only arginine deiminase (EC3.5.3.6) was spotted. Coding sequences (CDS) putative for D-lactate dehydrogenase (EC1.1.1.28), L-lactate dehydrogenase (EC1.1.1.27) and bacteriocin helveticin J were found within the genome together with plethora of other probiotic important genes. The strain harbours only resistant genes putative for Lincosamide (lnuC) and Tetracycline resistant genes (tetW). There was no hit found for virulence factors and probability of the strain being a human pathogen was zero. Two intact prophage regions were detected within the genome of L. reuteri PNW1 and nine CDS were identified for insertion sequence by OASIS which are belong to seven different families. Five putative CDS were identified for the CRISPR, each associated with Cas genes. Maximum zone of inhibition exhibited by the bacteriocin produced L. reuteri PNW1 is 20.0±1.00 mm (crude) and 23.3±1.15 mm (at 0.25 mg/ml) after being partially purified. With the strain predicted as non-human pathogen, coupled with many other identified desired features, L. reuteri PNW1 stands a chance of making good and safe candidates for probiotic, though further in-vivo investigations are still necessary.

Proteobiotics as a new antimicrobial therapy

Antibiotic resistance is a major concern for healthcare. The emergence of resistant bacteria has contributed to an increase in cost, morbidity, and mortality rates of patients. There is evidence to suggest that the inhibition of bacteria's virulence strategies would downregulate their pathogenesis and stop infections while also preventing more resistance. This concept became the backbone of many studies in the arena of human microbiome. Through probiotic studies, novel compounds were discovered that possessed antimicrobial activity. These have become labeled as proteobiotics, i.e. metabolites from probiotics. Proteobiotics have demonstrated the ability to interrupt bacteria cell-to-cell communication. Currently, there is one approved product containing proteobiotic technologies for swine showing positive outcomes.

Combined dietary supplementation of long chain inulin and Lactobacillus acidophilus W37 supports oral vaccination efficacy against Salmonella Typhimurium in piglets

Routine use of antibiotics in livestock animals strongly contributed to the creation of multidrug-resistant Salmonella Typhimurium strains (STM). Vaccination is an alternative to the use of antibiotics but often suffers from low efficacy. The present study investigated whether long-chain inulin (lcITF) and Lactobacillus acidophilus W37 (LaW37) can support vaccination efficacy against STM and if the interventions influence possible gut microbiota changes. Piglets received daily supplementation until sacrifice. Animals were vaccinated on day 25 after birth, one day after weaning, and were challenged with STM on days 52–54. Dietary intervention with lcITF/LaW37 enhanced vaccination efficacy by 2-fold during challenge and resulted in higher relative abundance of Prevotellaceae and lower relative abundance of Lactobacillaceae in faeces. Although strongest microbial effects were observed post STM challenge on day 55, transient effects of the lcITF/LaW37 intervention were also detected on day 10 after birth, and post-weaning on day 30 where increased relative abundance of faecal lactobacilli was correlated with higher faecal consistency. LcITF treatment increased post-weaning feed efficiency and faecal consistency but did not support vaccination efficacy. Vaccination in immune-immature young animals can be enhanced with functional additives which can simultaneously promote health in an ingredient-dependent fashion.

Expression of immune regulatory genes correlate with the abundance of specific Clostridiales and Verrucomicrobia species in the equine ileum and cecum

Billions of bacteria inhabit the gastrointestinal tract. Immune-microbial cross talk is responsible for immunological homeostasis, and symbiotic microbial species induce regulatory immunity, which helps to control the inflammation levels. In this study we aimed to identify species within the equine intestinal microbiota with the potential to induce regulatory immunity. These could be future targets for preventing or treating low-grade chronic inflammation occurring as a result of intestinal microbial changes and disruption of the homeostasis. 16S rRNA gene amplicon sequencing was performed on samples of intestinal microbial content from ileum, cecum, and colon of 24 healthy horses obtained from an abattoir. Expression of genes coding for IL-6, IL-10, IL-12, IL-17, 18 s, TNFα, TGFβ, and Foxp3 in the ileum and mesenteric lymph nodes was measured by qPCR. Intestinal microbiota composition was significantly different in the cecum and colon compared to the ileum, which contains large abundances of Proteobacteria. Especially members of the Clostridiales order correlated positively with the regulatory T-cell transcription factor Foxp3 and so did the phylum Verrucomicrobia. We conclude that Clostridiales and Verrucomicrobia have the potential to induce regulatory immunity and are possible targets for intestinal microbial interventions aiming at regulatory immunity improvement.

New Levan-Type Exopolysaccharide from Bacillus amyloliquefaciens as an Antiadhesive Agent against Enterotoxigenic Escherichia coli

A special levan-type exopolysaccharide (EPS) from Bacillus amyloliquefaciens JN4 with antiadhesive activity against enterotoxigenic Escherichia coli (ETEC) was purified and identified. Chemical analysis indicated that EPS-JN4 with a low molecular weight of 8 kDa is composed of fructose and glucose with a molar ratio of 46.1:1. Structural analysis clarified that EPS-JN4 contains a main chain of β-(2,6)-linked Fruf residues and intensive branches of a single 2-linked Fruf at every six residues. Furthermore, the superior antiadhesive activity of EPS-JN4 against ETEC showed its potential usage as an antiadhesive agent for diarrhea prevention. EPS-JN4 is a specific type of levan family, for its small molecular size and intensive branches. The results expand the knowledge on structural types of levan and illustrate its potential as an antiadhesive agent for diarrhea prevention, which will be conducive to elucidate the relation between structure and function.

Whole-Genome Sequence of Lactobacillus acidophilus PNW3, Isolated from Weaned Piglets of the Indigenous South African Windsnyer Pig Breed

A draft genome sequence of Lactobacillus acidophilus PNW3 is reported. The genome assembly is 1,857,655 bp long in 25 contigs with an N 50 value of 230,557 bp and a G+C content of 34.6%. The total number of predicted protein-coding genes is 1,776, with 58 predicted RNAs and 42 predicted pseudogenes.

Antibacterial activity and mode of action of acetone crude leaf extracts of under-investigated Syzygium and Eugenia (Myrtaceae) species on multidrug resistant porcine diarrhoeagenic Escherichia coli

BACKGROUND

Diarrhoea, a global economically important disease burden affecting swine and, especially piglets, is commonly caused by infection with entero-toxigenic E. coli (ETEC). Adherence of ETEC to porcine intestinal epithelial cells following infection, is necessary for its pathogenesis. While antimicrobials are commonly given as therapy or as feed additives for prophylaxis against microbial infections, the concern over increased levels of antimicrobial resistance necessitate the search for safe and effective alternatives in livestock feed. Attention is shifting to natural products including plants as suitable alternatives to antimicrobials. The activity of acetone crude leaf extracts of nine under-explored South African endemic plants from the Myrtaceae family with good antimicrobial activity were tested against pathogenic E. coli of porcine origin using a microplate serial dilution method. Bioautography, also with p-iodonitrotetrazolium violet as growth indicator was used to view the number of bioactive compounds in each extract. In vitro toxicity of extracts was determined against Caco-2 cells using the 3-(4,5-dimethythiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay. The antimicrobial susceptibility of E. coli isolates was tested on a panel of antimicrobials using the Kirby-Bauer agar diffusion method while the anti-adherence mechanism was evaluated using a Caco-2 cell enterocyte anti-adhesion model.

RESULTS

The MIC of the extracts ranged from 0.07-0.14 mg/mL with S. legatii having the best mean MIC (0.05 mg/mL). Bioautography revealed at least two active bands in each plant extract. The 50% lethal concentration (LC₅₀) values ranged between 0.03-0.66 mg/mL. Eugenia zeyheri least cytotoxic (LC₅₀ = 0.66 mg/ml) while E. natalitia had the highest cytotoxicity (LC₅₀ = 0.03 mg/mL). All the bacteria were completely resistant to doxycycline and colistin sulphate and many of the plant extracts significantly reduced adhesion of E. coli to Caco-2 cells.

CONCLUSIONS

The extracts of the plants had good antibacterial activity as well as a protective role on intestinal epithelial cells against enterotoxigenic E. coli bacterial adhesion. This supports the potential use of these species in limiting infection causes by E. coli. Some of these plants or extracts may be useful as phytogenic feed additives but it has to be investigated by animal feed trials.

Engineering the microbiome for animal health and conservation

IMPACT STATEMENT

Considering the clear effects of microbiota on important aspects of animal biology and development (including in humans), this topic is timely and broadly appealing, as it compels us to consider the possibilities of altering the microbiome (without antibiotics) to positively affect animal health. In this review, we highlight three general approaches to manipulating the microbiome that have demonstrated success and promise for use in animal health. We also point out knowledge gaps where further inquiry would most benefit the field. Our paper not only provides a short and digestible overview of the current state of application, but also calls for further exploration of the microbial diversity at hand to expand our toolkit, while also leveraging the diversity and flexibility of animal systems to better understand mechanisms of efficacy.

Designer Probiotics: The Next-Gen High Efficiency Biotherapeutics

The probiotic engineering is a cutting edge technology for improving disease diagnosis, treating gastrointestinal disorders and infectious diseases, and improving nutrition and ecological health. Use of bioengineered microorganisms in animals has different targets and prospects owing to differences in their anatomy, physiology, and feeding habits. In ruminants, the bioengineered microorganism is primarily aimed to enhance nutrient utilization, detoxify toxic plant metabolites, and lessen the enteric methanogenesis, while in non-ruminants, the bioengineered microorganisms are aimed to enhance nutrient utilizations, confer protection against pathogens, and inhibit infectious agents.

Highlights

The microorganisms can be engineered to enhance their metabolic efficiency

The bioengineered microorganisms could solve the burgeoning problem of drug-resistant pathogens

The recombinant probiotics are promising therapeutic agents against infectious diseases.

Evaluation of protective effect of Lactobacillus acidophilus La-5 on toxicity and colonization of Clostridium difficile in human epithelial cells in vitro

Clostridium difficile infection is a range of toxin - mediated intestinal diseases that is often acquired in hospitals and small communities in developed countries. The main virulence factors of C. difficile are two exotoxins, toxin A and toxin B, which damage epithelial cells and manifest as colonic inflammation and mild to severe diarrhea. Inhibiting C. difficile adherence, colonization, and reducing its toxin production could substantially minimize its pathogenicity and lead to faster recovery from the disease. This study investigated the efficacy of probiotic secreted bioactive molecules from Lactobacillus acidophilus La-5, in decreasing C. difficile attachment and cytotoxicity in human epithelial cells in vitro. L. acidophilus La-5 cell-free supernatant (La-5 CFS) was used to treat the hypervirulent C. difficile ribotype 027 culture with subsequent monitoring of cytotoxicity and adhesion. In addition, the effect of pretreating cell lines with La-5 CFS in protecting cells from the cytotoxicity of C. difficile culture filtrate or bacterial cell attachment was examined. La-5 CFS substantially reduced the cytotoxicity and cytopathic effect of C. difficile culture filtrate on HT-29 and Caco-2 cells. Furthermore, La-5 CFS significantly reduced attachment of the C. difficile bacterial cells on both cell lines. It was also found that pretreatment of cell lines with La-5 CFS effectively protected cell lines from cytotoxicity and adherence of C. difficile. Our study suggests that La-5 CFS could potentially be used to prevent and cure C. difficile infection and relapses.