Effect of Oral Administration of Weissella confusa on Fecal and Plasma Ethanol Concentrations, Lipids and Glucose Metabolism in Wistar Rats Fed High Fructose and Fat Diet.

Background and purpose: In previous investigations, Weissella confusa was shown to lack the metabolic pathway from fructose to mannitol and to produce ethanol when cultivated in the presence of fructose. Hence, we assessed the effect of oral administration of W. confusa (strain NRRL-B-14171) on blood and fecal ethanol concentrations, glucose and lipid metabolism and traits of the metabolic syndrome in Wistar rats (n=27) fed diets with two different fat and fructose levels and with or without the addition of W. confusa during a total intervention time of 15 weeks (105 days).

Materials and methods: From week 1 to 6, rats were given a medium fructose and fat (MFru-MF) diet containing 28% fructose and 10% fat without the addition of W. confusa (control group, n=13) or mixed with 30 g per kg diet of lyophilized W. confusa (10.56 ± 0.20 log CFU/g; W. confusa group, n=14). From week 7 to 15, the percentage of dietary fructose and fat in the control and W. confusa group was increased to 56% and 16%, respectively (high fructose-high fat (HFru-HF) diet).

Results: In HFru-HF-fed rats, W. confusa was detected in feces, regardless of whether W. confusa was added to the diet or not, but not in rats receiving the MFru-MF diet without added W. confusa or in an additional control group (n=10) fed standard rat food without fructose, increased fat content and W. confusa. This indicates that fecal W. confusa may be derived from orally administered W. confusa as well as - in the case of high fructose and fat intake and obesity of rats - from the intestinal microbiota. As shown by multifactorial ANOVA, blood ethanol, the relative liver weight, serum triglycerides, and serum cholesterol as well as fecal ethanol, ADH, acetate, propionate and butyrate, but not lactate, were significantly higher in the W. confusa - compared to the control group.

Discussion: This is the first in vivo trial demonstrating that heterofermentative lactic acid bacteria lacking the mannitol pathway (like W. confusa) can increase fecal and blood ethanol concentrations in mammals on a high fructose-high fat diet. This may explain why W. confusa resulted in hyperlipidemia and may promote development of NAFLD in the host.