The rise of human populations and the growth of cities contribute to the depletion of natural resources, increase their cost, and create potential climatic changes. To overcome difficulties in supplying populations and reducing the resource cost, a search for alternative pharmaceutical, nanotechnology, and energy sources has begun. Among the alternative sources, microalgae are the most promising because they use carbon dioxide (CO₂) to produce biomass and/or valuable compounds. Once produced, the biomass is ordinarily harvested and processed (downstream program). Drying, grinding, and extraction steps are destructive to the microalgal biomass that then needs to be renewed. The extraction and purification processes generate organic wastes and require substantial energy inputs. Altogether, it is urgent to develop alternative downstream processes. Among the possibilities, milking invokes the concept that the extraction should not kill the algal cells. Therefore, it does not require growing the algae anew. In this review, we discuss research on milking of diatoms. The main themes are (a) development of alternative methods to extract and harvest high added value compounds; (b) design of photobioreactors; (c) biodiversity and (d) stress physiology, illustrated with original results dealing with oleaginous diatoms.

In recent years, microalgae have become a source of molecules for a healthy life. Their composition of carbohydrates, peptides, lipids, vitamins and carotenoids makes them a promising new source of antioxidant molecules. Skeletal muscle is a tissue that requires constant remodeling via protein turnover, and its regular functioning consumes energy in the form of adenosine triphosphate (ATP), which is produced by mitochondria. Under conditions of traumatic exercise or muscular diseases, a high production of reactive oxygen species (ROS) at the origin of oxidative stress (OS) will lead to inflammation and muscle atrophy, with life-long consequences. In this review, we describe the potential antioxidant effects of microalgae and their biomolecules on mitochondrial functions and skeletal muscular oxidative stress during exercises or in musculoskeletal diseases, as in sarcopenia, chronic obstructive pulmonary disease (COPD) and Duchenne muscular dystrophy (DMD), through the increase in and regulation of antioxidant pathways and protein synthesis.

Oleaginous diatoms accumulate lipids of biotechnological interest when exposed to nutrient stress conditions such as nitrogen starvation. While accumulation mechanisms are well-known and have been engineered to improve lipid production, degradation mechanisms remain poorly investigated in diatoms. Identifying lipid-degrading enzymes is the initial step to understanding the catabolic processes. In this study, an in silico screening of the genome of Phaeodactylum tricornutum led to the identification of 57 putative triacylglycerol lipases (EC 3.1.1.3) grouped in 4 families. Further analysis revealed the presence of conserved domains and catalytic residues of lipases. Physico-chemical characteristics and subcellular localization predictions highlighted that a majority of these putative proteins are hydrophilic and cytosolic, suggesting they could be recruited to lipid droplets directly from the cytosol. Among the 57 identified putative proteins, three lipases were identified as possibly involved in lipophagy due to a potential vacuolar localization. The expression of the mRNA corresponding to the 57 proteins was then searched in 3 transcriptomic datasets obtained under nitrogen starvation. Nine genes were highly regulated and were considered as encoding enzymes with a probable important function in lipid catabolism. A tertiary structure prediction of these nine candidates yielded eight functional 3D models. Among those, two downregulated enzymes, Phatr3_J54974 and Phatr3_EG00720, were highlighted as good targets for future functional genomics and purification studies to investigate their role in lipid degradation.

Background: Physical activity, such as running, protects against cardiovascular disease and obesity but can induce oxidative stress. Athletes often consume antioxidants to counteract the overproduction of reactive oxygen and nitrogen species during exercise. Spirulina, particularly its phycocyanin content, activates the Nrf2 pathway, stimulating antioxidant responses. Studies show that phycocyanin enhances antioxidant defenses and reduces inflammation, potentially improving muscle adaptation and recovery. This study evaluates a Spirulina liquid extract (SLE) supplementation during endurance training, hypothesizing that phycocyanin improves oxidant status and performance in soleus and extensor digitorum longus muscles. Methods: Three-week-old male Wistar rats were divided into four groups: a sedentary control group (C), a sedentary group supplemented with SLE (SP), an endurance training group (T), and an endurance training group supplemented with SLE (SPT). After 8 weeks of treadmill training, blood and muscle were collected. Biochemical parameters and gene expression analyses were performed to assess the effects of training and supplementation. Results: The maximal aerobic speed improved significantly in the SPT group. Plasma lipid profiles showed a reduction in triglyceridemia, cholesterolemia, and atherogenic index in the trained groups, especially with SLE supplementation. Muscle malondialdehyde levels decreased in the SPT group compared to T. Gene expression analysis revealed upregulation of Nrf2 and mitochondrial biogenesis genes in both muscles, with differences between groups for genes related to glycogen storage and β-oxidation. Conclusions: This study demonstrated that SLE supplementation enhanced exercise performance and promoted muscle molecular adaptations. These findings suggest SLE as a promising functional food supplement for athletes, optimizing recovery and performance.