Mixotrophic growth regime as a strategy to develop microalgal bioprocess from nutrimental composition of tequila vinasses.

The selection of a suitable growth regime can increase the physiological performance of microalgae and improve bioprocess based on these microorganisms from agro-industrial residues. Thus, this study assessed the biotechnology capacity-biomass production, biochemical composition, and nutrient uptake-from tequila vinasses (TVs) as the nutrient source of three indigenous microalgae-Chlorella sp., Scenedesmus sp., and Chlamydomonas sp.-cultured under heterotrophic and mixotrophic conditions. The results demonstrated that under the mixotrophic regime, the three microalgae evaluated reached the highest nitrogen uptake, biomass production, and cell compound accumulation. Under this condition, Chlorella sp. and Scenedesmus sp. showed the highest nutrient uptake and biomass production, 1.7 ± 0.3 and 1.9 ± 0.3 g L-1, respectively; however, the biochemical composition, mainly carbohydrates and proteins, varied depending on the microalgal strain and its growth regime. Overall, our results demonstrated the biotechnological capacity of native microalgae from TVs, which may vary not only depending on the microalgal strain but also the culture strategy implemented and the characteristics of the residue used, highlighting-from a perspective of circular bio-economy-the feasibility of implementing microalgal bioprocess to reuse and valorize the nutrimental composition of TVs through biomass and high-valuable metabolite production, depicting a sustainable strategy for tequila agro-industry in Mexico.

Biotechnological potential of Chlorella sp. and Scenedesmus sp. microalgae to endure high CO2 and methane concentrations from biogas.

Biogas, a gaseous effluent from the anaerobic digestion of organic waste, is considered an important source of energy, since it has a composition mainly of methane (CH4; 55-75%) and CO2 (20-60%). Today, CO2 from biogas is an excellent carbon source to induce high microalgal biomass production; however, each microalga strain can have different optimal CO2 concentrations for maximizing their bio-refinery capacity as well as different ability to endure stressful conditions of industrial effluents. This study assessed the bio-refinery capacity of Chlorella sp. and Scenedesmus sp., native of Lago de Chapala, Mexico, from biogas, as well as the effect of high CO2 and methane concentrations on the physiological performance to grow, capture CO2 and biochemical composition of both microalgae cultured under different biogas compositions. The results show that both microalgae have the biotechnological potential to endure biogas compositions of 25% CO2-75% CH4. Under this condition, the biomass production attained by Chlorella sp. and Scenedesmus sp. was 1.77 ± 0.32 and 2.25 ± 0.20 g L-1, respectively, with a biochemical composition mainly of carbohydrates and proteins. Overall, this study demonstrates that both microalgae have the ability to endure the stressful biogas composition without affecting their physiological capacity to capture CO2 and biosynthesize high-value metabolites. Moreover, it is worth highlighting the importance of screening wild-type microalgae from local ecosystems to determine their physiological capacity for each biotechnological application.