Kombucha is a two-stage fermented sweetened tea beverage that uses yeast and lactic acid bacteria (LAB) to convert sugars into ethanol and lactate and acetic acid bacteria (AAB) to oxidize ethanol to acetate. Its popularity as a beverage grew from claims of health benefits derived from this vibrant microbial bioconversion. While recent studies have shed light on the diversity of cultures in Kombucha fermentation, there is limited information on the diversity, and especially viability, of cultures in retail beverages that advertise the presence of Kombucha and probiotic cultures. In this study, 12 Kombucha beverages produced by different manufacturers throughout the US were purchased and microbially characterized. Eight of the beverages contained viable Kombucha cultures, while 3 of the remaining 4 had viable Bacillus cultures as added probiotics. Amplicon profiling revealed that all contained Kombucha yeast and bacteria cells. The dominant yeasts detected were Lachancea cidri (10/12), Brettanomyces (9/12), Malassezia (6/12), and Saccharomyces (5/12). Dominant LAB included Liquorilactobacillus and Oenococcus oeni, and AAB were Komagataeibacter, Gluconobacter, and Acetobacter. One beverage had a significant amount of Zymomonas mobilis, an ethanol-producing bacterium from Agave cactus. While Kombucha beverages differ in the types and viability of cultures, all except one beverage contained detectable viable cells.

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are a class of medications used to treat and manage type 2 diabetes mellitus (T2DM) and obesity. The present narrative review explores potential interactions between the gut microbiome and GLP-1 RAs. Limited research has been conducted at the intersection of the gut microbiome and GLP-1 RA therapy. Therefore, this review focuses on potential relationships among GLP-1 RA, the microbiome, body weight, dietary changes, and gastrointestinal symptoms. The review of the current literature reveals significant gaps, particularly concerning the role of diet in mediating or confounding any impact of GLP-1 RA medications on the gut microbiome. Therefore, the body of the review is structured as a series of proposed directional and causal relationships. The limited available evidence suggests changes in behavior, diet, and weight loss resulting from GLP-1 RA treatment are the primary drivers of microbiome changes observed after GLP-1 RA treatment. The review concludes by proposing directions for future studies to clarify the complex interplay between GLP-1 RAs, the gut microbiome, diet, and obesity management.

Kombucha is a two-stage fermented sweetened-tea beverage that uses yeast and lactic acid bacteria (LAB) to convert sugars into ethanol and lactate, and acetic acid bacteria (AAB) to oxidize ethanol to acetate. Its popularity as a beverage grew from claims of health-benefits derived from this vibrant microbial bioconversion. While recent studies have shed light on the diversity of cultures during a Kombucha fermentation, there is limited information on the diversity, and especially viability, of cultures in retail beverages that advertise the presence of Kombucha and probiotic cultures. In this study, 12 Kombucha beverages produced by different manufacturers throughout the US were purchased and microbially characterized. Eight of the beverages contained viable Kombucha cultures, while 3 of the remaining 4 had viable Bacillus cultures as added probiotics. Amplicon profiling revealed all contained Kombucha yeast and bacteria cells. The dominant yeast detected were Lachancea cidri (10/12), Brettanomyces (9/12), Malassezia (6/12) and Saccharomyces (5/12). Dominant LAB included Liquorilactobacillus and Oenococcus oeni, and AAB were Komagataeibacter, Gluconobacter and Acetobacter. One beverage had a significant amount of Zymomonas mobilis, an ethanol producing bacterium from Agave cactus. While Kombucha beverages differ in the types and viability of cultures, all except one beverage contained detectable viable cells.

Interactions of structural and physicochemical properties of food (e.g. texture, viscosity, and solubility), known as the food matrix, are primary drivers of host digestive kinetics. While the impact of matrix-driven variability on nutrient bioaccessibility, glycemic response, and caloric absorption is well documented, these dynamics are often overlooked in diet-microbiome research. Adequately modeling the spatiotemporal availability of microbial substrate is essential to understanding how dietary patterns impact the microbiome throughout the gastrointestinal tract. This narrative review 1) synthesizes current evidence on how food processing and structure affect human digestion and absorption of macronutrients; 2) illustrates how host digestive kinetics impact forms and quantity of substrate delivered and available to the gut microbiota; and 3) identifies challenges and knowledge gaps in current diet–microbiome research regarding food structure. The challenges and knowledge gaps discussed here call for in vivo models that can better model microbial substrate availability throughout the gastrointestinal tract to improve our understanding of diet–microbiome interactions.