• Energy Research

Supplementing the diet of ruminants with agro-industrial by-products is a common practice. In this study, we applied an untargeted lipidomics approach to study the changes in the milk lipid metabolite profiles linked to the addition of different doses of spent coffee grounds (SCG) to the diet of lactating goats. The carryover of caffeine from feed to milk was also studied. Compared to controls, the milk of goats on the SCG diet showed higher levels of cholesteryl esters, sphingomyelins, and phospholipids, while nonesterified fatty acids were downregulated. After 12 h from the last SCG dose, the carry-over of caffeine was, on average, 3%. Collectively, our results establish that SCG supplementation induces changes in the milk levels of complex lipid molecules and causes the transfer of caffeine and caffeine metabolites from feed to milk.

Long-term spatial missions will require sustainable methods for biomass production using locally available resources. This study investigates the feasibility of cultivating Chlorella vulgaris, a high value microalgal specie, using a leachate of Martian regolith and synthetic human urine as nutrient sources. The microalga was grown in a standard medium (BBM) mixed with 0, 20, 40, 60, or 100 % Martian medium (MM). MM did not significantly affect final biomass concentrations. Total carbohydrate and protein contents decreased with increasing MM fractions between 0 % and 60 %, but biomass in the 100% MM showed the highest levels of carbohydrates and proteins (25.2 ± 0.9 % and 37.1 ± 1.4 % of the dry weight, respectively, against 19.0 ± 1.7 % and 32.0 ± 2.7 % in the absence of MM). In all MM-containing media, the fraction of the biomass represented by total lipids was lower (by 3.2 to 4.5%) when compared to BBM. Conversely, total carotenoids increased, with the highest value (97.3 ± 1.5 mg/100 g) measured with 20% MM. In a three-dimensional principal component analysis of triacylglycerols, samples clustered according to growth media; a strong impact of growth media on triacylglycerol profiles was observed. Overall, our findings suggest that microalgal biomass produced using regolith and urine can be used as a valuable component of astronauts' diet during missions to Mars.

Solid-state (13)C nuclear magnetic resonance (NMR) and elemental analysis techniques were used to monitor the degradation of wheat bran by the white-rot fungus Pleurotus ostreatus during a 62-day cultivation period. The weight loss and in vitro organic matter digestibility of the substrate were also evaluated after fungal treatment. The (13)C NMR spectra of degraded wheat bran samples showed a lower content in carbohydrates and a higher content in aliphatic and carboxylic groups than the untreated control sample. In parallel, changes in the wheat bran elemental composition evidenced a decrease in carbon content and a concomitant increase in nitrogen and oxygen content during mycelium growth. These results clearly indicate the occurrence of progressive changes in the composition of wheat bran during fungal treatment and are interpreted in terms of preferential degradation of amorphous vs. crystalline polysaccharides by the fungal mycelium and accumulation of proteins in the substrate. At the end of the cultivation period, the treated samples experienced an average weight loss of 20% and an increase in organic matter digestibility of 17%.