Gut microbial induction of host immune maturation exemplifies host-microbe mutualism. We colonized germ-free (GF) mice with mouse microbiota (MMb) or human microbiota (HMb) to determine whether small intestinal immune maturation depends on a coevolved host-specific microbiota. Gut bacterial numbers and phylum abundance were similar in MMb and HMb mice, but bacterial species differed, especially the Firmicutes. HMb mouse intestines had low levels of CD4(+) and CD8(+) T cells, few proliferating T cells, few dendritic cells, and low antimicrobial peptide expression--all characteristics of GF mice. Rat microbiota also failed to fully expand intestinal T cell numbers in mice. Colonizing GF or HMb mice with mouse-segmented filamentous bacteria (SFB) partially restored T cell numbers, suggesting that SFB and other MMb organisms are required for full immune maturation in mice. Importantly, MMb conferred better protection against Salmonella infection than HMb. A host-specific microbiota appears to be critical for a healthy immune system.

Gut Immune Maturation Depends Upon Colonization with Host-Specific Microbiota

Trabajo presentado en la 113th General Meeting of the American Society for Microbiology, celebrada en Denver, Estados Unidos, del 18 al 21 de mayo de 2013

Species concept for prokaryotes

Phylosymbiosis, where similarities in host-associated microbial communities recapitulate the phylogeny of their hosts, is a newly recognized yet pervasive pattern in the field of host-microbe interactions. While phylosymbiosis has been documented across many systems, we still have a poor understanding of the mechanisms that underlie this emergent pattern. Host selection of the microbiome is a widely cited mechanism, yet other basic ecological and evolutionary processes (dispersal, drift and diversification) may also be at play. This paper discusses the roles that each of these processes and their interactions may play in yielding phylosymbiotic signals across hosts. Finally, this paper will identify open questions and methods that are required to better understand the relative contributions of these basic processes to phylosymbiosis. Given that phylosymbiosis has been shown to relate to functional components of host fitness, understanding the processes that contribute to these patterns will be important for our understanding of the ecology and evolution of host-microbe interactions. This article is part of the theme issue 'Conceptual challenges in microbial community ecology'.

https://royalsocietypublishing.org/doi/pdf/10.1098/rstb.2019.0251

Ecological and evolutionary mechanisms underlying patterns of phylosymbiosis in host-associated microbial communities.

United States is the largest producer and the second largest exporter of broiler meat in the world. In the US, broiler production is largely converting to antibiotic-free programs which has caused an increase in morbidity and mortality within broiler farms. Escherichia coli and Clostridium perfringens are two important pathogenic bacteria readily found in the broiler environment and result in annual billion-dollar losses from colibacillosis, gangrenous dermatitis, and necrotic enteritis. The broiler industry is in search of non-antibiotic alternatives including novel vaccines, prebiotics, probiotics, and housing management strategies to mitigate production losses due to these diseases. This review provides an overview of the broiler industry and antibiotic free production, current challenges, and emerging research on antibiotic alternatives to reduce pathogenic microbial presence and improve bird health.

https://www.mdpi.com/2076-2607/8/10/1533/pdf

Avian Pathogenic Escherichia coli and Clostridium perfringens : Challenges in No Antibiotics Ever Broiler Production and Potential Solutions

Prenatal nutrition is crucial for embryonic development and neonatal growth, and has the potential to be a main determinant of life-long health. In the present study, we used a layer chick model to investigate the effects of in ovo feeding (IOF) of L-arginine (Arg) on growth, intestinal development, intestinal microbiota and metabolism. The treatments included the non-injected control, saline-injected control, and saline containing 2, 6, or 10 mg Arg groups. IOF Arg increased early intestinal index and villus height, and enhanced uptake of residual yolk lipid, contributing to subsequent improvement in the early growth performance of chicks. Prenatal Arg supplementation also increased the early microbial α-diversity, the relative abundance of Lactobacillales and Clostridiales, and decreased the relative abundance of Proteobacteria of cecum in chicks. Furthermore, the shift of cecal microbiota composition and the colonization of potential probiotics were accelerated by IOF of Arg. Simultaneously, metabolomics showed that metabolisms of galactose, taurine-conjugated bile acids and lipids were modulated to direct more energy and nutrients towards rapid growth of intestine at the beginning of post-hatch when embryos received IOF of Arg. Prenatal Arg supplementation showed beneficial effects on the early intestinal development, cecal microbiota and host metabolism of layer chicks, contributing to subsequent improvement in the early growth performance. These findings provide new insight into the role of IOF of Arg in the establishment of the gut microbiota of newly-hatched layer chicks, and can expand our fundamental knowledge about prenatal nutrition, early bacterial colonization and intestinal development in neonate.

/pdf/dynamic-alterations-in-early-intestinal-development-1w4qntboca.pdf

Dynamic alterations in early intestinal development, microbiota and metabolome induced by in ovo feeding of L-arginine in a layer chick model.

Evaluation of the impact of in ovo administered bacteria on microbiome of chicks through 10 days of age.

Research Note: Evaluating fecal shedding of oocysts in relation to body weight gain and lesion scores during Eimeria infection.

Given that recent advances in metagenomics have highlighted the importance of intestinal microbes for poultry health, there has been a corresponding search for early manipulation strategies of intestinal microbiota in order to advance immune system development and optimize functional properties of growth. In this study, we used the in ovo technique as an experimental model to address how early bacterial intestinal colonization could affect the development and establishment of the mature ileal microbiota. Inoculations containing one of the following: 0.2 ml of 0.9% sterile saline (S), approximately 102 cells of Citrobacter freundii (CF), Citrobacter species (C2) or lactic acid bacteria (L) were administered via in ovo into the amnion. Results showed that Enterobacteriaceae abundance was negatively correlated with aging, although its high population at day of hatch affected the microbiota composition, delaying mature microbiota establishment. L treatment increased colonization of butyrate-producing bacteria by three and 10 days, and segmented filamentous bacteria in the lower ileum by 10 days. On the other hand, L-probiotic decreased the population of Enterococcaceae. In addition, L and C2 microbial communities were less diverse at 10 days than at three days in the upper ileum. Importantly, these findings provide a valuable resource for a potential study model for interactions between microbial colonization and associated immune responses. In conclusion, our analysis demonstrates that intestinal pioneer colonizers play a critical role in driving the course of microbial community composition and diversity over time, in which early-life exposure to L-based probiotic supported selection alongside greater colonization of symbiotic populations in the ileum of young broilers.

/pdf/intestinal-pioneer-colonizers-as-drivers-of-ileal-microbial-31xvko32hr.pdf

Intestinal pioneer colonizers as drivers of ileal microbial composition and diversity of broiler chickens

SUMMARY A variety of necrotic enteritis (NE) research methodologies exist in the literature, many with components that do not represent standard industry practices. The models tested here aimed to investigate multiple NE methods that represent common broiler production systems. Two preliminary experiments compared Eimeria maxima (EM) plus NetB-negative Clostridium perfringens (CP) and NetB-positive CP (CPB), and showed decreased BW gain (BWG) relative to non-challenge negative control (NC; P ≤ 0.05) across NE models, but no difference in NE lesion scores. Experiments 3 and 4 tested 2 EM strains (EMG or EMM6), CP, 3 CPB strains, washed CPB, or supernatant from washed CPB to determine the impact of NetB toxin when birds consumed a standard corn-soy diet. Groups with predisposing EM had the largest decrease in BWG (−19.50 to −28.35%) compared to the NC in experiment 3. Experiment 4 showed similar trends in EM groups with −20.88 to −22.09% change in BWG (P ≤ 0.05). Minimal % change in BWG occurred in all CPB groups, with less than 10% decrease. Increasing the amount of CP in feed to 2 L/d for 4 consecutive days resulted up to 17% decrease in BWG (P ≤ 0.05), but lesion scores were not significantly different than NC. When administered in the absence of EM, CP, regardless of the presence of NetB gene and inoculum, did not cause clinical NE in these experiments. A predisposing factor, such as EM, was required for development of clinical signs, gross macroscopic lesions, and decreased BWG when broilers were fed a standard diet.

Comparison of multiple methods for induction of necrotic enteritis in broilers. I

Proteomics has been used to investigate cross-talk between the intestinal microbiome and host biological processes. In this study, an in ovo technique and a proteomics approach was used to address how early bacterial colonization in the gastrointestinal tract (GIT) could modulate inflammatory and immune responses in young broilers. Embryos at 18 embryogenic days were inoculated with saline (S), 102 CFU of Citrobacter freundii (CF), Citrobacter species (C2), or lactic acid bacteria mixture (L) into the amnion. At 10 days posthatch, ileum samples from 12 birds per treatment were selected for tandem mass spectrometry analysis. Our further findings indicated that treatment-specific influences on early GIT microbiota resulted in different immune responses in mature broilers. Predicted functional analyses revealed activation of inflammation pathways in broilers treated in ovo with L and CF. Exposure to L enhanced functional annotation related to activation, trafficking of immune cells, and skeletal growth based-network, while CF inhibited biological functions associated with immune cell migration and inflammatory response. These results highlighted that proper immune function was dependent on specific GIT microbiota profiles, in which early-life exposure to L-based probiotic may have modulated the immune functions, whereas neonatal colonization of Enterobacteriaceae strains may have led to immune dysregulation associated with chronic inflammation.

/pdf/a-proteomic-view-of-the-cross-talk-between-early-intestinal-9eh0qhqfei.pdf

K.M. Wilson

Papers

Evaluation of the impact of in ovo administered bacteria on microbiome of chicks through 10 days of age.

Research Note: Evaluating fecal shedding of oocysts in relation to body weight gain and lesion scores during Eimeria infection.

Intestinal pioneer colonizers as drivers of ileal microbial composition and diversity of broiler chickens

Comparison of multiple methods for induction of necrotic enteritis in broilers. I

A Proteomic View of the Cross-Talk Between Early Intestinal Microbiota and Poultry Immune System.