Physiological responses and microbiota shifts after spermidine administration as a postbiotic on rodents fed a high-fat high-fructose diet.

The consumption of a high-fat high-fructose diet partly resemble the western dietary patterns, which is closely associated with excessive body adiposity and metabolic disorders, such as obesity and type 2 diabetes. Moreover, this unhealthy regime produces unfavourable changes on the faecal microbiota, potentially interfering with microorganisms postbiotic function, such as spermidine, a natural polyamine that has been involved in the control of weight gain. The study aimed to analyse the repercussions of spermidine supplementation on somatic measurements, metabolic markers, and the faecal microbiota profile of rats fed a diet rich in fat and fructose. Indeed, Wistar males with oral administration of spermidine (20 mg/kg/day) for 6 weeks were evaluated for food and energy intake, biochemical markers, and faecal microbiota signatures. The daily use of spermidine decreased weight gain ( P < 0.01), reduced feed efficiency ( P < 0.01), and attenuated visceral fat deposition ( P < 0.01), although no effect on energy intake, hepatic weight, triglyceride and glucose index and atherogenic indexes. Similarly, the consumption of spermidine partially restored the presence of microbial species, notably Akkermansia muciniphila. Elevated concentrations of this species were linked to a decrease in triglycerides ( P = 0.04), indicating that the supplementation of spermidine might contribute to managing energy fuel homeostasis in association with an obesogenic diet.

Lactobacillus rhamnosus GG administration partially prevents diet-induced insulin resistance in rats: a comparison with its heat-inactivated parabiotic.

Insulin resistance and type 2 diabetes are obesity-related health alterations, featuring an ever-increasing prevalence. Besides inadequate feeding patterns, gut microbiota alterations stand out as potential contributors to these metabolic disturbances. The aim of this study was to investigate whether the administration of a probiotic (Lactobacillus rhamnosus GG) effectively prevents diet-induced insulin resistance in rats and to compare these potential effects with those exerted by its heat-inactivated parabiotic. For this purpose, 34 male Wistar rats were fed a standard or a high-fat high-fructose diet, alone or supplemented with viable or heat-inactivated Lactobacillus rhamnosus GG. The body and white adipose tissue weight increases, induced by the obesogenic diet, were prevented by probiotic and parabiotic administration. The trend towards higher basal glucose levels and significantly higher serum insulin concentration observed in the non-treated animals fed with the obesogenic diet were effectively reverted by both treatments. Similar results were also found for serum adiponectin and leptin, whose levels were brought back by the probiotic and parabiotic administration to values similar to those of the control animals. Noteworthily, parabiotic administration significantly reduced skeletal muscle triglyceride content and activated CPT-1b compared to the non-treated animals. Finally, both treatments enhanced Akt and AS160 phosphorylation in the skeletal muscle compared to the non-treated animals; however, only parabiotic administration increased GLUT-4 protein expression in this tissue. These results suggest that heat-inactivated Lactobacillus rhamnosus GG seem to be more effective than its probiotic of origin in preventing high-fat high-fructose diet-induced insulin resistance in rats.

Removal of odorant dimethyl disulfide under alkaline and neutral conditions in biotrickling filters.

The aim of this paper was to evaluate the performance of biotrickling filters (BTFs) for treating low concentrations of dimethyl disulfide (DMDS), using different bacterial consortia adapted to consume reduced sulfur compounds under alkaline (pH ≈ 10) or neutral (pH ≈ 7) conditions. Solubility experiments indicated that the partition of DMDS in neutral and alkaline mineral media was similar to the value with distilled water. Respirometric assays showed that oxygen consumption was around ten times faster in the neutrophilic as compared with the alkaliphilic consortium. Batch experiments demonstrated that sulfate was the main product of the DMDS degradation. Two laboratory-scale BTFs were implemented for the continuous treatment of DMDS in both neutral and alkaline conditions. Elimination capacities of up to 17 and 24 g(DMDS) m(-3) h(-1) were achieved for the alkaliphilic and neutrophilic reactors with 100% removal efficiency after an initial adaptation and biomass build-up.

Dimethyl sulphide degradation using immobilized Thiobacillus thioparus in a biotrickling filter.

Gaseous dimethyl sulphide (DMS) was eliminated in a biotrickling filter with Thiobacillus thioparus grown in polyurethane foam cubes as carrier material. The temperature, pH and empty bed residence time of the gas were maintained at 30 degrees C, 7.0 and 40 s, respectively. In the first 45 days, DMS loads of around 2.0 gDMS m(-3) h(-1) were fed to the BTF to adapt T. thioparus to DMS consumption, attaining close to 100% removal efficiency (RE) on day 46, and the maximum elimination capacity (EC) was 4.0 gDMS m(-3) h(-1) with a RE of 77%. The overall performance was enhanced by adding a nitrogen-enriched (9x) medium but was negatively affected by high superficial liquid velocity (8.18 m h(-1)) and high pH (>7.5). Sulphate concentrations (up to 10 g L(-1)) showed no effect. The system supported shock loads up to 58 gDMS m(-3) h(-1) with increased elimination. With nitrogen-enriched medium and a pH of 7.0 it was possible to increase the EC of DMS up to a maximum of around 23 gDMS m(-3) h(-1) with 65% RE.