Milk kefir alters fecal microbiota impacting gut and brain health in mice.

Kefir is a fermented beverage made of a symbiotic microbial community that stands out for health benefits. Although its microbial profile is still little explored, its effects on modulation of gut microbiota and production of short-chain fatty acids (SCFAs) seems to act by improving brain health. This work aimed to analyze the microbiota profile of milk kefir and its effect on metabolism, oxidative stress, and in the microbiota-gut-brain axis in a murine model. The experimental design was carried out using C57BL-6 mice (n = 20) subdivided into groups that received 0.1 mL water or 0.1 mL (10% w/v) kefir. The kefir proceeded to maturation for 48 h, and then it was orally administered, via gavage, to the animals for 4 weeks. Physicochemical, microbiological, antioxidant analyzes, and microbial profiling of milk kefir beverage were performed as well as growth parameters, food intake, serum markers, oxidative stress, antioxidant enzymes, SCFAs, and metabarcoding were analyzed in the mice. Milk kefir had 76.64 ± 0.42% of free radical scavenging and the microbiota composed primarily by the genus Comamonas. Moreover, kefir increased catalase and superoxide dismutase (colon), and SCFAs in feces (butyrate), and in the brain (butyrate and propionate). Kefir reduced triglycerides, uric acid, and affected the microbiome of animals increasing fecal butyrate-producing bacteria (Lachnospiraceae and Lachnoclostridium). Our results on the brain and fecal SCFAs and the antioxidant effect found were associated with the change in the gut microbiota caused by kefir, which indicates that kefir positively influences the gut-microbiota-brain axis and contributes to the preservation of gut and brain health. KEY POINTS: • Milk kefir modulates fecal microbiota and SCFA production in brain and colon. • Kefir treatment increases the abundance of SCFA-producing bacteria. • Milk kefir increases antioxidant enzymes and influences the metabolism of mice.

First report on the enzymatic profile of Kretzschmaria zonata.

Enzymes from phytopathogenic fungi are desirable for biotechnological applications and a highly virulent phytopathogen shows great appeal for enzymes production. To assess the biotechnological potential of Kretzschmaria zonata, a plant pathogenic fungus, we analyzed its enzymatic profile after growth on six different types of lignocellulosic biomasses. The fungus was able to produce a wide variety of enzymes with superior xylanase activity. The corn cob induced the highest specific activity of xylanase, 56.30 U/mg of protein, as well as other important enzymatic activities such as endoglucanase, 11.20 U/mg of protein; pectinase, 4.52 U/mg of protein; and ß-glucosidase, 2.77 U/mg of protein. The highest release of xylose, 0.88 g/L, was observed after saccharification of 10% of alkaline pretreated sugarcane bagasse by a commercial cocktail supplemented with the crude extract from K. zonata after growth on corn cob. The fungus extract is rich in hemicellulases and accessory enzymes and the result showed synergism between the enzymes present in the commercial mixture and in the K. zonata extract. This is the first report concerning the biotechnological potential of the fungus K. zonata, especially regarding to its ability to produce plant biomass degrading enzymes related to second generation ethanol production.