In this review, we provide an overview of the dynamic changes within the microbiota and its metabolites that are implicated in establishing and maintaining gastrointestinal homeostasis during various stages of microbial colonization. The gradual conversion of the gut microbiota toward a mutualistic microbial community involves replacement of pioneer gut colonizers with bacterial taxa that are characteristic for the adult gut. An important microbial signature of homeostasis in the adult gut is the prevalence and activity of a diverse spectrum of bacterial (...) species that produce beneficial metabolites through metabolic interactions between microbial groups. Deciphering these microbial signatures and their metabolites that govern short and long‐term equilibrium, as well as imbalances in host‐microbial relationships, may provide novel diagnostic tools and/or therapeutic targets for specific disorders associated with intestinal dysbiosis and loss of homeostasis. (shrink)

I hypothesize here that the ability of probiotics to synthesize neuroactive compounds provides a unifying microbial endocrinology‐based mechanism to explain the hitherto incompletely understood action of commensal microbiota that affect the host's gastrointestinal and psychological health. Once ingested, probiotics enter an interactive environment encompassing microbiological, immunological, and neurophysiological components. By utilizing a trans‐disciplinary framework known as microbial endocrinology, mechanisms that would otherwise not be considered become apparent since any candidate would need to be shared among all three components. The range (...) of neurochemicals produced by probiotics includes neurochemicals for which receptor‐based targets on immune and neuronal elements (intestinal and extra‐intestinal) have been well characterized. Production of neurochemicals by probiotics therefore allows for their consideration as delivery vehicles for neuroactive compounds. This unifying microbial endocrinology‐based hypothesis, which may facilitate the selection and design of probiotics for clinical use, also highlights the largely unrecognized role of neuroscience in understanding how microbes may influence health.Editor's suggested further reading in BioEssays Harvesting the biological potential of the human gut microbiome Abstract. (shrink)