Characterization of cecal microbiota and response to an orally administered lactobacillus probiotic strain in the broiler chicken

Week-Old Chicks with High Bacteroides Abundance Have Increased Short-Chain Fatty Acids and Reduced Markers of Gut Inflammation

As important commensals in the chicken intestine, Bacteroides are essential complex carbohydrate degraders, and short-chain fatty acid (SCFA) producers that are highly adapted to the distal gut. Previous studies have shown large variation in Bacteroides abundance in young chickens. However, limited information is available regarding how this variation affects the gut microbiome and host immunity. To investigate how elevated or depleted Bacteroides levels affect gut microbial functional capacity and impact host response, we sampled 7-day-old broiler chickens from 14 commercial production flocks. Week-old broiler chickens were screened and birds with low Bacteroides (LB) and high Bacteroides (HB) abundance were identified via 16S rRNA gene amplicon sequencing and quantitative PCR (qPCR) assays. Cecal microbial functionality and SCFA concentration of chickens with distinct cecal Bacteroides abundance were profiled by shotgun metagenomic sequencing and gas chromatography, respectively. The intestinal immune responses of LB and HB chickens were assessed via reverse transcription qPCR. Results showed that the gut microbiota of the LB group had increased abundance of lactic acid bacteria pyruvate fermentation pathway, whereas complex polysaccharide degradation and SCFA production pathways were enriched in the HB group (P < 0.05), which was supported by increased SCFA concentrations in the ceca of HB chickens (P < 0.05). HB chickens also showed decreased expression of interleukin-1β and increased expression of interleukin-10 and tight-junction protein claudin-1 (P < 0.05). Overall, the results indicated that elevated Bacteroides may benefit the 7-day broiler gut and that further work should be done to confirm the causal role of Bacteroides in the observed positive outcomes. IMPORTANCE To date, limited information is available comparing distinct Bacteroides compositions in the chicken gut microbial communities, particularly in the context of microbial functional capacities and host responses. This study showed that possessing a microbiome with elevated Bacteroides in early life may confer beneficial effects to the chicken host, particularly in improving SCFA production and gut health. This study is among the first metagenomic studies focusing on the early life chicken gut microbiota structure, microbial functionality, and host immune responses. We believe that it will offer insights to future studies on broiler gut microbial population and their effects on host health.

Insight into dominant intestinal microbiota and the fatty acids profile of turkeys following the administration of synbiotic preparations

BACKGROUND

Probiotics and prebiotics are widely used as natural feed additives in the nutrition of farm animals, including poultry. The using of this type of preparation has a positive effect on animal welfare, human health and the environment. High potential is attributed to preparations combining probiotics and prebiotics, called synbiotics. The aim of the research was to confirm the beneficial effects of synbiotics on the performance of turkeys and the number of dominant intestinal microbiota. In addition, we also investigated the concentration of organic acids (lactic acid, short-chain and branched-chain fatty acids) in the excreta of turkeys.

RESULTS

The synbiotic supplementation of turkeys caused statistically significant (P < 0.05) differences in body weight of animals and European production efficiency factor (EPEF) compared to control group after 15 weeks of rearing. Administration of the synbiotics resulted in a significant (P < 0.05) reduction in the count of potential pathogens (Clostridium spp., Clostridium coccoides and Escherichia coli) but a significant (P < 0.05) increase in the count of beneficial microorganisms (lactobacilli and Bifidobacterium spp.) in the excreta of turkeys. Results of synbiotic supplementation showed that the short-chain fatty acids and lactic acid concentration were significantly (P < 0.05) increased, while the concentration of branched-chain fatty acids was decreased.

CONCLUSION

The results showed a beneficial influence of the synbiotics on the animals' performance, dominant intestinal microbiota and fatty acid profile in the excreta of turkeys. The developed synbiotics can be effectively used in nutrition of turkeys. © 2022 Society of Chemical Industry.

Protective Effects of Novel Lactobacillaceae Strains Isolated from Chicken Caeca against Necrotic Enteritis Infection: In Vitro and In Vivo Evidences

The present study aimed to show the benefits of novel lactic acid bacteria (LAB) strains isolated from the caeca of healthy chickens. These novel strains, identified as Limosilactobacillus reuteri and Ligilactobacillus salivarius, displayed high levels of lactic acid production, capability of biofilm formation, high aggregation and adhesion scores, and significant survival rates under conditions mimicking the chicken gastrointestinal tract (GIT). In addition, these novel Lactobacillaceae isolates were neither hemolytic nor cytotoxic. In vivo trials were able to establish their ability to reduce necrotic enteritis. Notably, a significant weight gain was registered, on day 10 of treatment, in the group of chickens fed with a mixture of L. reuteri ICVB416 and L. salivarius ICVB430 strains, as compared with the control group. This group has also shown a reduced number of lesions in the gut compared with other infected chicken groups. This study provides in vitro and in vivo evidence supporting the benefits of these novel Lactobacillaceae isolates for their use in poultry livestock as protective cultures to control the bacterial necrotic enteritis (NE) Clostridium perfringens.

Microbial taxa in dust and excreta associated with the productive performance of commercial meat chicken flocks

BACKGROUND

A major focus of research on the gut microbiota of poultry has been to define signatures of a healthy gut and identify microbiota components that correlate with feed conversion. However, there is a high variation in individual gut microbiota profiles and their association with performance. Population level samples such as dust and pooled excreta could be useful to investigate bacterial signatures associated with productivity at the flock-level. This study was designed to investigate the bacterial signatures of high and low-performing commercial meat chicken farms in dust and pooled excreta samples. Poultry house dust and fresh pooled excreta were collected at days 7, 14, 21, 28 and 35 of age from 8 farms of two Australian integrator companies and 389 samples assessed by 16S ribosomal RNA gene amplicon sequencing. The farms were ranked as low (n = 4) or high performers (n = 4) based on feed conversion rate corrected by body weight.

RESULTS

Permutational analysis of variance based on Bray-Curtis dissimilarities using abundance data for bacterial community structure results showed that company explained the highest variation in the bacterial community structure in excreta (R² = 0.21, p = 0.001) while age explained the highest variation in the bacterial community structure in dust (R² = 0.13, p = 0.001). Farm performance explained the least variation in the bacterial community structure in both dust (R² = 0.03, p = 0.001) and excreta (R² = 0.01, p = 0.001) samples. However, specific bacterial taxa were found to be associated with high and low performance in both dust and excreta. The bacteria taxa associated with high-performing farms in dust or excreta found in this study were Enterococcus and Candidatus Arthromitus whereas bacterial taxa associated with low-performing farms included Nocardia, Lapillococcus, Brachybacterium, Ruania, Dietzia, Brevibacterium, Jeotgalicoccus, Corynebacterium and Aerococcus.

CONCLUSIONS

Dust and excreta could be useful for investigating bacterial signatures associated with high and low performance in commercial poultry farms. Further studies on a larger number of farms are needed to determine if the bacterial signatures found in this study are reproducible.

Ameliorative Effects of Antibiotic-, Probiotic- and Phytobiotic-Supplemented Diets on the Performance, Intestinal Health, Carcass Traits, and Meat Quality of Clostridium perfringens-Infected Broilers

Simple Summary

Necrotic enteritis is considered the most important economic problem for the poultry industry due to the sudden death rates of up to 50%. However, there is limited information concerning the ameliorative role of probiotic and/or phytobiotic compounds in the prevention of Clostridium perfringens infections in broilers. Hence, this trial is conducted to evaluate the influence of some antibiotic, probiotic and phytobiotic compounds (Maxus, CloStat, Sangrovit Extra, CloStat + Sangrovit Extra, and Gallipro Tect) on the growth performance, carcass traits, intestinal health, and meat quality of broiler chicks. The obtained in vivo results highlight that a probiotic- and/or phytobiotic-supplemented diet has many positive effects on the performance, organ weight, and meat quality of broilers. Besides, a notable reduction in the lesion score is observed with a combined probiotic and phytobiotic diet.

Abstract

The poultry industry needs efficient antibiotic alternatives to prevent necrotic enteritis (NE) infections. Here, we evaluate the effects of probiotic and/or prebiotic dietary supplementation on performance, meat quality and carcass traits, using only an NE coinfection model, in broiler chickens. Three hundred and twenty-four healthy Ross 308 broiler chicks are allocated into six groups. Taking a 35 d feeding trial, the chicks are fed a basal diet with 0.0, 0.1, 0.5, 0.12, 0.5 + 0.12, and 0.2 g Kg⁻¹ for the control (T₁), Avilamycin (Maxus; T₂), live probiotic (CloStat (Bacillus subtilis);T₃), natural phytobiotic compounds (Sangrovit Extra (sanguinarine and protopine); T₄), CloStat + Sangrovit Extra (T₅), and spore probiotic strain (Gallipro Tect (Bacillus subtilis spores); T₆) treatments, respectively. Occurring at 15 days-old, chicks are inoculated with Clostridium perfringens. The obtained results reveal that all feed additives improve the performance, feed efficiency, and survival rate, and reduces the intestinal lesions score compared with the control group. The T₆ followed by T₃ groups show a significant (p < 0.05) increase in some carcass traits, such as dressing, spleen, and thymus percentages compared with other treatments. Also, T₅ and T₆ have significantly recorded the lowest temperature and pHu values and the highest hardness and chewiness texture values compared to the other treated groups. To conclude, probiotics combined with prebiotic supplementation improves the growth, meat quality, carcass characterization and survival rate of NE-infected broiler chickens by modulating gut health conditions and decreasing lesion scores. Moreover, it could be useful as an ameliorated NE disease alternative to antibiotics in C. perfringens coinfected poultry.

Effect of Antibiotic, Phytobiotic and Probiotic Supplementation on Growth, Blood Indices and Intestine Health in Broiler Chicks Challenged with Clostridium perfringens

Simple Summary

Necrotic enteritis is one of the most important economic issues in the poultry industry, associated with sudden death rates of up to 50%. However, there is limited information on the role of probiotics and/or phytobiotic compounds on the treatment and prevention of Clostridium perfringens infections in broiler chicks. This study aimed to assess the effects of probiotic compounds (Maxus, CloStat, Sangrovit Extra, CloStat + Sangrovit Extra and Gallipro Tech) on the growth performance, blood biochemistry and intestinal health of broiler chicks in vivo. The results demonstrated that the inclusion of probiotic and/or phytobiotic compounds has a positive effect on performance, blood constituents, liver histopathology, intestinal morphology and histopathology. Furthermore, a notable reduction in both lesion scores was observed when probiotics and phytobiotics alone or in combination were included in the diets.

Abstract

This study evaluated the effects of feed additives on the growth, blood biochemistry and intestinal health of broiler chicks. A total of 378 of broiler chicks (Ross 308) were randomly allotted to seven groups. Chicks were fed a basal diet with 0.0 (control negative), 0.0 (control positive), 0.1, 0.5, 0.12, 0.5 + 0.12 and 0.2 g Kg⁻¹ of Maxus, CloStat, Sangrovit Extra, CloStat + Sangrovit Extra and Gallipro Tech, respectively for 35 days. After 15 days, the chicks were inoculated with Clostridium perfringens. All feed additives were found to enhance growth performance and feed efficiency. The best feed conversion ratio was found in the Negative Control, CloStat + Sangrovit Extra and Gallipro Tect groups, respectively. A notable increase in villus length, total villus area, small intestine weight, ilium weight and total lesion score was found in chicks supplemented with Bacillus subtilis. Besides, the dietary inclusion of phytobiotic compounds showed potential in reducing the serum Alanine aminotransferase (ALT) concentration and increasing the glucose levels. All intestine and liver histopathological signs were reduced in chicks fed a probiotic-supplemented diet. Our findings indicate that supplementation with probiotics and phytobiotics alone or in combined form can be used to enhance performance, intestine health and blood constituents against C. perfringens infection in broiler chicks.

Effect of Lactobacillus acidophilus D2/CSL (CECT 4529) supplementation in drinking water on chicken crop and caeca microbiome

In this study we gained insights into the effects of the supplementation with Lactobacillus acidophilus D2/CSL (CECT 4529) in the chicken drinking water on crop and caeca microbiomes. The probiotic was supplemented at the concentrations of 0.2 g Lactobacillus acidophilus/day/bird and 0.02 g Lactobacillus acidophilus/day/bird and its effect on the crop and caeca microbiomes was assessed at 14 and 35 days of rearing. The results showed that mean relative abundance of Lactobacillus acidophilus in the caeca did not show significative differences in the treated and control birds, although Lactobacillus acidophilus as well as Faecalibacterium prausnitzii, Lactobacillus crispatus and Lactobacillus reuteri significantly increased over time. Moreover, the treatment with the high dose of probiotic significantly increased the abundance of Clostridium asparagiforme, Clostridium hathewayi and Clostridium saccharolyticum producing butyrate and other organic acids supporting the chicken health. Finally, at 35 days, the Cell division protein FtsH (EC 3.4.24.-) and the Site-specific recombinase genes were significantly increased in the caeca of birds treated with the high dose of probiotic in comparison to the control group. The results of this study showed that Lactobacillus acidophilus D2/CSL (CECT 4529) supplementation in the drinking water at the concentrations of 0.2 and 0.02 g Lactobacillus acidophilus/day/bird improved beneficial microbes and functional genes in broiler crops and caeca. Nevertheless, the main site of action of the probiotic is the crop, at least in the early stage of the chicken life. Indeed, at 14 days Lactobacillus acidophilus was significantly higher in the crops of chickens treated with the high dose of LA in comparison to the control (14.094 vs 1.741%, p = 0.036).

Dissect the mode of action of probiotics in affecting host-microbial interactions and immunity in food producing animals

Prophylactic antimicrobials have been widely used in food animal production with the aim to prevent infectious diseases, enhance feed efficiency, and promote growth. However, the extensive use of antimicrobials in food animal production systems has led to the emergence of antimicrobial resistant pathogens, which are potential threats to human and animal health. Probiotics have been proposed to be a promising alternative of prophylactic antimicrobials, with potential beneficial effects on the host animal by improving the balance of intestinal microbiota and host immunity. Although an increasing body of evidence shows that probiotics could directly or indirectly affect gut microbiota and host immune functions, the lack of the understanding of how probiotics influence host-microbial interaction and immunity is one of the reasons for controversial findings from many animal trials, especially in food production animals. Therefore, in this review we focused on the most recent (last ten years) studies on how gut microbiota and host immune function changes in response to probiotics in food production animals (swine, poultry, and ruminant). In addition, the relationship between microbial changes and host immune function was illustrated, and how such relationship differs among animal species was further compared. Moreover, the future directions concerning the mechanisms of how probiotics modulate host-microbial interactions and host immunity were highlighted, which may assist in the optimal supplementation strategy to maximize the efficacy of probiotics to improve animal gut health and productivity.

Effects of Lactobacillus acidophilus on the growth performance and intestinal health of broilers challenged with Clostridium perfringens

Background

Clostridium perfringens is the main etiological agent of necrotic enteritis. Lactobacilli show beneficial effects on intestinal health in infectious disease, but the protective functions of lactobacilli in C. perfringens-infected chickens are scarcely described. This study examined the effects of Lactobacillus acidophilus (L. acidophilus) on the growth performance and intestinal health of broiler chickens challenged with Clostridium perfringens (C. perfringens) over a 28-day period. Using a 2 × 2 factorial arrangement of treatments, a total of 308 1-day-old male Arbor Acres broiler chicks were included to investigate the effects of Lactobacillus acidophilus (L. acidophilus) on the growth performance and intestinal health of broiler chickens challenged with Clostridium perfringens (C. perfringens) during a 28-day trial.

Results

During infection (d 14-21), C. perfringens challenge decreased the average daily gain (P <  0.05), and increased feed conversion ratio and the mortality rate (P <  0.05). However, dietary supplementation with L. acidophilus increased the body weight of C. perfringens-infected broilers on d 21 (P <  0.05), and tended to decrease the mortality (P = 0.061). C. perfringens challenge decreased the villus height (P <  0.05), the ratio of villus height to crypt depth (P <  0.05) and OCLN (occludin) mRNA expression (P <  0.05), and increased the pro-inflammatory cytokine expression in the spleen and jejunum, the intestinal populations of C. perfringens and Escherichia (P < 0.05), and the serum content of endotoxin (P < 0.05), regardless of L. acidophilus supplementation. In contrast, dietary L. acidophilus reducedthe intestinal lesion score of challenged broilers (P < 0.05), the mRNA expression of pro-inflammatory cytokines, ileal populations of Escherichia and serum endotoxin content (P < 0.05), but increased the intestinal Lactobacillus populations (P < 0.05), irrespective of C. perfringens challenge.

Conclusion

Dietary addition of L. acidophilus could improve the intestinal health and reduce the mortality of broilers suffering from necrotic enteritis.

Host and Environmental Factors Affecting the Intestinal Microbiota in Chickens

The initial development of intestinal microbiota in poultry plays an important role in production performance, overall health and resistance against microbial infections. Multiplexed sequencing of 16S ribosomal RNA gene amplicons is often used in studies, such as feed intervention or antimicrobial drug trials, to determine corresponding effects on the composition of intestinal microbiota. However, considerable variation of intestinal microbiota composition has been observed both within and across studies. Such variation may in part be attributed to technical factors, such as sampling procedures, sample storage, DNA extraction, the choice of PCR primers and corresponding region to be sequenced, and the sequencing platforms used. Furthermore, part of this variation in microbiota composition may also be explained by different host characteristics and environmental factors. To facilitate the improvement of design, reproducibility and interpretation of poultry microbiota studies, we have reviewed the literature on confounding factors influencing the observed intestinal microbiota in chickens. First, it has been identified that host-related factors, such as age, sex, and breed, have a large effect on intestinal microbiota. The diversity of chicken intestinal microbiota tends to increase most during the first weeks of life, and corresponding colonization patterns seem to differ between layer- and meat-type chickens. Second, it has been found that environmental factors, such as biosecurity level, housing, litter, feed access and climate also have an effect on the composition of the intestinal microbiota. As microbiota studies have to deal with many of these unknown or hidden host and environmental variables, the choice of study designs can have a great impact on study outcomes and interpretation of the data. Providing details on a broad range of host and environmental factors in articles and sequence data repositories is highly recommended. This creates opportunities to combine data from different studies for meta-analysis, which will facilitate scientific breakthroughs toward nutritional and husbandry associated strategies to improve animal health and performance.

Recent Advances and Understanding of Using Probiotic-Based Interventions to Restore Homeostasis of the Microbiome for the Prevention/Therapy of Bacterial Diseases

The importance of the microbiome in health and disease has galvanized interest in using manipulations of the gastrointestinal ecosystem to prevent and/or combat gut bacterial infections and to restore mucosal homeostasis in patients with generalized microbial imbalances (i.e., dysbiosis), including the human inflammatory bowel diseases, Crohn's disease, and ulcerative colitis. Probiotics, prebiotics, or their combination use (i.e., synbiotics) are one mechanism for modifying the microbiota and exerting direct and indirect effects on the host immune responses and metabolomics profiles. These beneficial effects are transferred through various pathways, including the production of antimicrobial peptides, promoting the growth of beneficial microbes and enhancing immunomodulatory functions via various metabolites. While probiotic therapy has been used empirically for decades with mixed success, the recent advances in molecular and mass spectrophotometric techniques for the characterization of the complexity and diversity of the intestinal microbiome has aided in better understanding of host-microbe interactions. It is important to better understand the functional properties of the microbiome, because it is now clear that the microbiota secretes many metabolites that have a direct impact on host immune responses. This information will improve selection of the most appropriate probiotic strains that selectively target intestinal disease processes.

Development of cecal-predominant microbiota in broilers during a complete rearing using denaturing gradient gel electrophoresis

Understanding of the intestinal microbiota is crucial to enhance intestinal health and performance parameters in animals. A more exhaustive research of the intestinal microbiota of broilers could be of interest to implement appropriate intervention measures. The aim of the present study was to investigate the development of the predominant cecal microbiota in broilers that were fed a Lactobacillus salivarius DSPV 001P strain during a complete rearing using denaturing gradient gel electrophoresis (DGGE). Bacterial DNA from cecal samples of 24 broilers at different ages were amplified by PCR and analysed by DGGE. A total of 35 DGGE products were excised and sequenced. Distinctive differences in bacterial communities were observed in the caecum as broilers age. At early stages, identified bacteria within the caecum of broilers were predominantly Clostridium-related species. Also, some sequences had the closest match to the genus Escherichia/Shigella. Furthermore, the caecum was a reservoir rich in uncultured bacteria. The major difference observed in our study was an increase of potentially beneficial Lactobacillus at Day 45. These results may be attributed to modulation of the microbiota by the probiotic supplementation. The obtained data could be relevant for future studies related to the influence of the microbiota resulting from probiotic supplementation on the performance and the immunological parameters of broilers.

Supplemental effects of probiotic Bacillus subtilis fmbJ on growth performance, antioxidant capacity, and meat quality of broiler chickens

This study aimed to investigate the supplemental effects of probiotic Bacillus subtilis fmbJ (BS fmbJ) on growth performance, antioxidant capacity, and meat quality of broiler chickens. A total of 240 day-old male Arbor Acres (AA) broiler chickens were randomly allotted to 4 treatments and raised for 6 wk. Each treatment had 6 replicate pens with ten birds per replicate. Birds in the control group (CON) were fed diets without BS fmbJ and antibiotics. The BS groups were fed the basal diets with BS fmbJ at 2 × 10¹⁰ cfu/kg (BS-1 group), BS fmbJ at 3 × 10¹⁰ cfu/kg (BS-2 group), BS fmbJ at 4 × 10¹⁰ cfu/kg (BS-3 group) without antibiotics for 42 d. In the study, dietary supplementation with BS fmbJ significantly improved (P < 0.05) the average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) of broilers from 21 to 42 d and 1 to 42 d. At 42 d, the final body weight was increased (P < 0.05) in BS-2 group compared with that in CON. Dietary BS fmbJ significantly increased (P < 0.05) serum IgA and IgG concentrations of broilers after 42 days raising. The glutathione (GSH), glutathione reductase (GR), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) activity of serum and liver were increased (P < 0.05), and methane dicarboxylic aldehyde (MDA) contents in serum and liver were decreased (P < 0.05) by BS fmbJ added into the broiler diets. Dietary supplementation with BS fmbJ significantly decreased (P < 0.05) reactive oxygen species (ROS) contents in liver mitochondria of broilers. Additionally, the expression of antioxidant enzyme gene including nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were improved (P < 0.05) by BS fmbJ added into the broiler diets. Among measuring items of chicken breast meat quality, the drip loss, cooking loss, shear force, L*_24 h, a*_24 h, b*_45 min, and b*_24 h values were influenced (P < 0.05) by BS fmbJ provided in the diet. Based on these results, Bacillus subtilis fmbJ could be acted as a beneficial feed additive with antioxidant capacity in broiler diets.

Alternatives to Antibiotics to Prevent Necrotic Enteritis in Broiler Chickens: A Microbiologist's Perspective

Since the 2006 European ban on the use of antibiotics as growth promoters in animal feed, numerous studies have been published describing alternative strategies to prevent diseases in animals. A particular focus has been on prevention of necrotic enteritis in poultry caused by Clostridium perfringens by the use of microbes or microbe-derived products. Microbes produce a plethora of molecules with antimicrobial properties and they can also have beneficial effects through interactions with their host. Here we review recent developments in novel preventive treatments against C. perfringens-induced necrotic enteritis in broiler chickens that employ yeasts, bacteria and bacteriophages or secondary metabolites and other microbial products in disease control.

Effect of dietary inclusion level of a multi-species probiotic on broiler performance and two biomarkers of their caecal ecology

The effect of the dietary inclusion level of a three-species probiotic on broiler performance, nutrient digestibility, caecal microbiota composition and volatile fatty acid (VFA) pattern was evaluated. Day-old Cobb broilers (n = 448) were allocated in four treatments for 6 weeks. Each treatment had four replicates (two per gender) of 28 broilers each. Depending on the type of addition per kg basal diet, treatments were C (no other addition), PL (108 colony forming units of probiotic), PH (109 colony forming units of probiotic) and A (2.5 mg avilamycin). Overall bodyweight gain was better (P = 0.002) in PL and PH than in the control (2082 g) by 8.7% and 7.5%, respectively, while treatment PL did not differ from A (2341 g), which showed the highest bodyweight gain. The ileal and total-tract apparent digestibility of DM and the apparent metabolisable energy content corrected for N improved linearly (P ≤ 0.05) with the probiotic level. Fluorescent in situ hybridisation analysis showed caecal Bifidobacterium levels to increase linearly (P = 0.006) with the probiotic level. Probiotic administration resulted in altered caecal VFA patterns compared with the control. Gender effects (P ≤ 0.05) were noted for caecal levels of C. histolyticum group, Bacteroides fragilis group and Streptococcus spp., while interactions (P ≤ 0.05) of treatment with gender were seen for Bifidobacterium and all VFA components, except for acetate. In conclusion, beneficial effects on bodyweight gain, DM digestibility, apparent metabolisable energy content corrected for N, caecal Bifidobacterium levels and VFA patterns were noted with both probiotic inclusion levels.

Ecology and metabolism of the beneficial intestinal commensal bacterium Faecalibacterium prausnitzii

Faecalibacterium prausnitzii is a major commensal bacterium, and its prevalence is often decreased in conditions of intestinal dysbiosis. The phylogenic identity of this bacterium was described only recently. It is still poorly characterized, and its specific growth requirements in the human gastrointestinal tract are not known. In this review, we consider F. prausnitzii metabolism, its ecophysiology in both humans and animals, and the effects of drugs and nutrition on its population. We list important questions about this beneficial and ubiquitous commensal bacterium that it would be valuable to answer.

Short-chain fructo-oligosaccharides modulate intestinal microbiota and metabolic parameters of humanized gnotobiotic diet induced obesity mice

Prebiotic fibres like short-chain fructo-oligosaccharides (scFOS) are known to selectively modulate the composition of the intestinal microbiota and especially to stimulate Bifidobacteria. In parallel, the involvement of intestinal microbiota in host metabolic regulation has been recently highlighted. The objective of the study was to evaluate the effect of scFOS on the composition of the faecal microbiota and on metabolic parameters in an animal model of diet-induced obesity harbouring a human-type microbiota. Forty eight axenic C57BL/6J mice were inoculated with a sample of faecal human microbiota and randomly assigned to one of 3 diets for 7 weeks: a control diet, a high fat diet (HF, 60% of energy derived from fat)) or an isocaloric HF diet containing 10% of scFOS (HF-scFOS). Mice fed with the two HF gained at least 21% more weight than mice from the control group. Addition of scFOS partially abolished the deposition of fat mass but significantly increased the weight of the caecum. The analysis of the taxonomic composition of the faecal microbiota by FISH technique revealed that the addition of scFOS induced a significant increase of faecal Bifidobacteria and the Clostridium coccoides group whereas it decreased the Clostridium leptum group. In addition to modifying the composition of the faecal microbiota, scFOS most prominently affected the faecal metabolome (e.g. bile acids derivatives, hydroxyl monoenoic fatty acids) as well as urine, plasma hydrophilic and plasma lipid metabolomes. The increase in C. coccoides and the decrease in C. leptum, were highly correlated to these metabolic changes, including insulinaemia, as well as to the weight of the caecum (empty and full) but not the increase in Bifidobacteria. In conclusion scFOS induce profound metabolic changes by modulating the composition and the activity of the intestinal microbiota, that may partly explain their effect on the reduction of insulinaemia.

Faecal D/L lactate ratio is a metabolic signature of microbiota imbalance in patients with short bowel syndrome

Our objective was to understand the functional link between the composition of faecal microbiota and the clinical characteristics of adults with short bowel syndrome (SBS).

Sixteen patients suffering from type II SBS were included in the study. They displayed a total oral intake of 2661±1005 Kcal/day with superior sugar absorption (83±12%) than protein (42±13%) or fat (39±26%). These patients displayed a marked dysbiosis in faecal microbiota, with a predominance of Lactobacillus/Leuconostoc group, while Clostridium and Bacteroides were under-represented. Each patient exhibited a diverse lactic acid bacteria composition (L. delbrueckii subsp. bulgaricus, L. crispatus, L. gasseri, L. johnsonii, L. reuteri, L. mucosae), displaying specific D and L-lactate production profiles in vitro. Of 16 patients, 9/16 (56%) accumulated lactates in their faecal samples, from 2 to 110 mM of D-lactate and from 2 to 80 mM of L-lactate. The presence of lactates in faeces (56% patients) was used to define the Lactate-accumulator group (LA), while absence of faecal lactates (44% patients) defines the Non lactate-accumulator group (NLA). The LA group had a lower plasma HCO3⁻ concentration (17.1±2.8 mM) than the NLA group (22.8±4.6 mM), indicating that LA and NLA groups are clinically relevant sub–types. Two patients, belonging to the LA group and who particularly accumulated faecal D-lactate, were at risk of D-encephalopathic reactions. Furthermore, all patients of the NLA group and those accumulating preferentially L isoform in the LA group had never developed D-acidosis. The D/L faecal lactate ratio seems to be the most relevant index for a higher D- encephalopathy risk, rather than D- and L-lactate faecal concentrations per se. Testing criteria that take into account HCO3⁻ value, total faecal lactate and the faecal D/L lactate ratio may become useful tools for identifying SBS patients at risk for D-encephalopathy.

Arabinoxylans and inulin differentially modulate the mucosal and luminal gut microbiota and mucin-degradation in humanized rats

The endogenous gut microbiota affects the host in many ways. Prebiotics should favour beneficial intestinal microbes and thus improve host health. In this study, we investigated how a novel class of potential prebiotic long-chain arabinoxylans (LC-AX) and the well-established prebiotic inulin (IN) modulate the gut microbiota of humanized rats. Six weeks after axenic rats were inoculated with a human faecal microbiota, their colonic microbiota was similar to this inoculum (∼ 70%), whereas their caecal microbiota was enriched with Verrucomicrobia and Firmicutes concomitant with lower abundance of Bacteroidetes. Moreover, different Bifidobacterium species colonized the lumen (B. adolescentis) and mucus (B. longum and B. bifidum). Both LC-AX and IN increased SCFA levels and induced a shift from acetate towards health-promoting propionate and butyrate respectively. By applying a high-resolution phylogenetic micro-array (HITChip) at the site of fermentation (caecum), IN and LC-AX were shown to stimulate bacterial groups with known butyrate-producers (Roseburia intestinalis, Eubacterium rectale, Anaerostipes caccae) and bifidobacteria (B. longum) respectively. Prebiotic administration also resulted in lower caecal abundances of the mucin-degrading Akkermansia muciniphila and potentially more mucin production by the host. Both factors might explain the increased caecal mucin levels for LC-AX (threefold) and IN (sixfold). These mucins were degraded along the colon, resulting in high faecal abundances of Akkermansia muciniphila for LC-AX and especially IN-treated rats. Finally, the microbial changes caused an adaptation period for the host with less weight gain, after which the host fine-tuned the interaction with this altered microbiota. Our results demonstrate that next to IN, LC-AX are promising prebiotic compounds by stimulating production of health-promoting metabolites by specific microbes in the proximal regions. Further, prebiotic supplementation shifted mucin degradation to distal regions, where mucin-degraders may produce beneficial metabolites (e.g. propionate by Akkermansia muciniphila), so that prebiotics may potentially improve gut health along the entire length of the intestine.

Oral treatment of chickens with lactobacilli influences elicitation of immune responses

Commensal microbes in the intestine are in constant interaction with host cells and play a role in shaping the immune system. Lactobacillus acidophilus, Lactobacillus reuteri, and Lactobacillus salivarius are members of the chicken intestinal microbiota and have been shown to induce different cytokine profiles in mononuclear cells in vitro. The objective of the present study was to examine the effects of these bacteria individually or in combination on the induction of antibody- and cell-mediated immune responses in vivo. The birds received lactobacilli weekly via oral gavage starting on day of hatch and subsequently, at 14 and 21 days, were immunized with sheep red blood cells (SRBC), keyhole limpet hemocyanin (KLH), Newcastle disease virus vaccine, and infectious bursal disease virus vaccine. Antibody responses in serum were measured weekly for 4 weeks beginning on the day of primary immunization. The cell-mediated immune response was evaluated at 21 days postimmunization by measurement of gamma interferon (IFN-γ) production in splenocytes stimulated with inactivated vaccine antigens. L. salivarius-treated birds had significantly more serum antibody to SRBC and KLH than birds that were not treated with probiotics. L. salivarius-treated birds also had decreased cell-mediated immune responses to recall antigen stimulation. L. reuteri treatment did not significantly affect the systemic immune response, while L. acidophilus treatment increased the antibody response to KLH. These results indicate that systemic antibody- and cell-mediated immune responses can be modulated by oral treatment with lactobacilli but that these bacteria may vary in their ability to modulate the immune response.

Lactobacillus strain ecology and persistence within broiler chickens fed different diets: identification of persistent strains

Lactobacilli are autochthonous residents in the chicken gastrointestinal tract, where they may potentially be used as probiotics, competitive exclusion agents, or delivery vehicles. The aim of this study was to use an in vivo model to investigate the effect of diet and competing lactic acid bacteria on the colonization of inoculated Lactobacillus strains, with the goal of identifying strains which can consistently colonize or persist for an extended period of several weeks. Chicken-derived Lactobacillus strains were genetically marked with rifampin resistance and administered on day 0 to chickens fed either a normal commercial diet or a specially formulated high-protein diet. Chickens fed the high-protein diet were also coinoculated with two different mixes of additional lactic acid bacteria. Enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR) was used to identify rifampin-resistant isolates recovered from chickens. Three strains, belonging to the species Lactobacillus agilis, Lactobacillus crispatus, and Lactobacillus vaginalis, were commonly reisolated from the chickens on both diets at days 21 and 42. The ability of these strains to persist was confirmed in a second chicken trial. All three strains persisted throughout the production period in the chickens fed a commercial diet, while only the L. agilis and L. vaginalis strains persisted in the chickens fed the high-protein diet. In both in vivo trials, competing lactic acid bacteria modified representation of the strains recovered, with all three stains capable of competing in the presence of one or both mixes of coinoculated strains. The in vivo model successfully identified three persistent strains that will be characterized further.