Human gastrointestinal (GI) tract microbiome-derived pro-inflammatory neurotoxins from Bacteroides fragilis: Effects of low fiber diets and environmental and lifestyle factors

Overview Homo sapiens harbor a complex and dynamic community of microorganisms, collectively known as ‘the microbiome’, that together constitute the largest ‘dispersed organ system’ on and within the body, cumulatively more massive, more metabolically active, and much more genetically complex than all of the multiple cell types of the human liver. Together with host cells and their genes, the microbiome constitutes the ‘metaorganism’, defined as an assemblage of interacting biological entities with significant commensal or symbiotic benefit to the entire lifeform. The human GI-tract microbiome’s dynamic complexity of different microbial species is largely dependent on diet, dietary fiber, environmental and lifestyle-factors, and the most recent evidence suggests that this in turn contributes to human behavior and immunological and neurological health and disease. This communication-perspectives article will briefly discuss the relatively recent research advances at the intersection of human GI-tract microbiome-derived pro-inflammatory neurotoxins and the effects of low-fiber diets, and environmental and lifestyle factors on microbial abundance and speciation. In addition to the nutrients obtained from our diet it is becoming increasingly clear that beneficial dietary effects on the maintenance of a healthy GI-tract microbiome may also reduce the abundance of pro-inflammatory neurotoxins with gastric, immunological and neurological implications. This paper will further focus on current research developments: (i) of one of the human GI-tract’s most abundant Gram-negative bacterial species Bacteroides fragilis (of the phylum Bacteriodetes); (ii) discuss recent advances in our understanding of the contribution of B. fragilis-derived pro-inflammatory neurotoxins and