Euglena gracilis polysaccharide modulated gut dysbiosis of obese individuals via acetic acid in an in vitro fermentation model.

Gut dysbiosis is a characteristic feature of obesity and targeting gut microbiota presents a promising approach to attenuate obesity. Euglena gracilis polysaccharide (EGP) has emerged as a potential prebiotic capable of promoting health-beneficial bacteria. However, its effects on the gut dysbiosis of obese individuals remain unclear. This study investigated the impacts of EGP on gut microbiota from both non-obese and obese individuals using an in vitro fermentation model. Results showed that EGP significantly altered the gut microbiota composition and metabolism. Specifically, EGP improved the relative abundance of Paeniclostridium, Clostridium_sensu_stricto_1 and Paraclostridium of the non-obese individuals and Providencia, Enterococcus and Bacteroides of the obese individuals. Metabolomics results showed EGP significantly altered the lipid metabolism especially in the obese group with enriched bile secretion and cholesterol metabolism pathways. Noting that acetic acid was significantly increased in both groups, these acetic acid favorable microbiota from non-obese individuals was collected with acetic acid supplementation. Transplantation of these acetic acid-induced microbiota (AAiM) notably improved the richness and diversity of fecal microbiota of the obese individuals, enhancing the growth of probiotics like Bacteroides and Bifidobacterium. Consequently, AAiM significantly restructured macronutrients (including amino acids, carbohydrates and lipids) metabolism of the gut microbiota from obese individuals. Altogether, this study underscores the potential of EGP and acetic acid favorable microbiota in manipulating obesity-associated gut dysbiosis via acetic acid production.