No abstract

Microalgae biomasses offer important benefits regarding macromolecules that serve as promising raw materials for sustainable production. In the present study, the microalgae Arthrospira platensis DHR 20 was cultivated in horizontal photobioreactors (HPBR), with and without temperature control, in batch mode (6 to 7 days), with anaerobically digested cattle wastewater (ACWW) as substrate. High dry biomass concentrations were observed (6.3–7.15 g L −1 ). Volumetric protein, carbohydrate, and lipid productivities were 0.299, 0.135, and 0.108 g L −1 day −1 , respectively. Promising lipid productivities per area were estimated between 22.257 and 39.446 L ha −1 year −1 . High CO 2 bio-fixation rates were recorded (875.6–1051 mg L −1 day −1 ), indicating the relevant potential of the studied microalgae to mitigate atmospheric pollution. Carbon concentrations in biomass ranged between 41.8 and 43.6%. ACWW bioremediation was satisfactory, with BOD 5 and COD removal efficiencies of 72.2–82.6% and 63.3–73.6%. Maximum values of 100, 95.5, 92.4, 80, 98, and 94% were achieved concerning the removal of NH 4 + , NO 3 − , P t , SO 4 2− , Zn, and Cu, respectively. Total and thermotolerant coliform removals reached 99–99.7% and 99.7–99.9%. This microalgae-mediated process is, thus, promising for ACWW bioremediation and valuation, producing a microalgae biomass rich in macromolecules that can be used to obtain friendly bio-based products and bioenergy. Supplementary Information The online version contains supplementary material available at 10.1007/s12155-021-10258-4.

Aim Using in vitro assay and eukaryotic cell model of Saccharomyces cerevisiae, we investigated the impact of microbial fermentation on antioxidant activity of phenolic substances. Methods and Results Caffeic acid phenethyl ester (CAPE) and mangiferin were fermented by lactic acid bacteria (LAB), and the antioxidant activity of the fermented products was compared to that of the pure substances. This was assessed using HPLC and in vitro by 2,2-Diphenyl-1-picrylhydrazyl (DPPH), and in vivo in yeast cells. The wild-type strain (BY4741) and its isogenic mutants in glutathione (Δgsh1), catalase (Δctt1), and superoxide dismutase (Δsod1) were treated with CAPE and mangiferin, fermented or not, and exposed to hydrogen peroxide (H2O2)-induced stress. The antioxidant activity was evaluated by cellular viability, intracellular oxidation and lipid peroxidation. We expected that fermentation would change the antioxidant activity of phenolic substances. While HPLC analysis revealed changes in the composition of fermented products, significant alterations in antioxidant activity were only observed when using mutant strains. The fermentation of mangiferin increased dependency on GSH compared to the respective pure phenolic substance to resolve H2O2-induced stress. Additionally, CAPE appeared to act as a preconditioning agent, enhancing antioxidant responses and promoting increased tolerance to H2O2 stress, and this mechanism was maintained after fermentation. Conclusions This study highlights that fermentation impacts the enzymatic mechanism of oxidative stress resolution, even though differences could not be observed in in vitro assays or wild-type strain.