Cecal microbiota transplantation:unique influence of cecal microbiota from divergently selected inbred donor lines on cecal microbial profile,serotonergic activity,and aggressive behavior of recipient chickens

Background Accumulating evidence from human trials and rodent studies has indicated that modulation of gut microbiota affects host physiological homeostasis and behavioral characteristics.Similarly,alterations in gut micro-biota could be a feasible strategy for reducing aggressive behavior and improving health in chickens.The study was conducted to determine the effects of early-life cecal microbiota transplantation(CMT)on cecal microbial composi-tion,brain serotonergic activity,and aggressive behavior of recipient chickens.Methods Chicken lines 63 and 72 with nonaggressive and aggressive behavior,respectively,were used as donors and a commercial strain Dekalb XL was used as recipients for CMT.Eighty-four 1-d-old male chicks were randomly assigned to 1 of 3 treatments with 7 cages per treatment and 4 chickens per cage(n=7):saline(control,CTRL),cecal solution of line 6_(3)(6_(3)-CMT),and cecal solution of line 7_(2)(7_(2)-CMT).Transplantation was conducted via oral gavage once daily from d 1 to 10,and then boosted once weekly from week 3 to 5.At weeks 5 and 16,home-cage behavior was recorded,and chickens with similar body weights were assigned to paired aggression tests between the treat-ments.Samples of blood,brain,and cecal content were collected from the post-tested chickens to detect CMT-induced biological and microbiota changes.Results 63-CMT chickens displayed less aggressive behavior with a higher hypothalamic serotonergic activity at week 5.Correspondingly,two amplicon sequence variants(ASVs)belonging to Lachnospiraceae and one Ruminococ-caceae UCG-005 ASV were positively correlated with the levels of brain tryptophan and serotonin,respectively.7_(2)-CMT chickens had lower levels of brain norepinephrine and dopamine at week 5 with higher levels of plasma serotonin and tryptophan at week 16.ASVs belonging to Mollicutes RF39 and GCA-900066225 in 7_(2)-CMT chickens were nega-tively correlated with the brain 5-hydroxyindoleacetic acid(5-HIAA)at week 5,and one Bacteroides ASV was negatively correlated with plasma serotonin at week 16.Conclusion Results indicate that CMT at an early age could regulate aggressive behavior via modulating the cecal microbial composition,together with central serotonergic and catecholaminergic systems in recipient chickens.The selected CMT could be a novel strategy for reducing aggressive behavior through regulating signaling along the microbiota-gut-brain axis.

Gut microbiota research nexus:One Health relationshipbetween human,animal,and environmental resistomes

The emergence and rapid spread of antimicrobial resistance is of global public health concern.The gut microbiota harboring diverse commensal and opportunistic bacteria that can acquire resistance via horizontal and vertical gene transfers is considered an important reservoir and sink of antibiotic resistance genes(ARGs).In this review,we describe the reservoirs of gut ARGs and their dynamics in both animals and humans,use the One Health perspective to track the transmission of ARG-containing bacteria between humans,animals,and the environment,and assess the impact of antimicrobial resistance on human health and socioeconomic development.The gut resistome can evolve in an environment subject to various selective pressures,including antibiotic administration and environmental and lifestyle factors(e.g.,diet,age,gender,and living conditions),and interventions through probiotics.Strategies to reduce the abundance of clinically relevant antibiotic-resistant bacteria and their resistance determinants in various environmental niches are needed to ensure the mitigation of acquired antibiotic resistance.With the help of effective measures taken at the national,local,personal,and intestinal management,it will also result in preventing or minimizing the spread of infectious diseases.This review aims to improve our understanding of the correlations between intestinal microbiota and antimicrobial resistance and provide a basis for the development of management strategies to mitigate the antimicrobial resistance crisis.