• Energy Research

The effect of sugarcane molasses on lipid content and fatty acids methyl ester (FAME) profile by Chromochloris zofingiensis is investigated in this work. For this purpose, the strain has been cultivated under mixotrophic conditions in a medium amended with specific concentrations of molasses (0.5 g/L, 1 g/L, and 2 g/L) able to sustain microalgae growth. Better biomass concentration, lipid content, and lipid productivity (1.6 g/L, 38% wt, and 286 mg/L/day) than the control (1.32 g/L, 16% wt, and 139 mg/L/day) were obtained with 2 g/L of molasses. The highest value of the total lipid content (42% wt) was reached with 1 g/L of molasses. FAME profile revealed a 97% composition in C16-C18 with no statistically meaningful differences among the three concentrations of molasses tested. The most represented fatty acids were C18:1 oleic (> 38% wt), C18:2 linoleic (> 21% wt), and C16:0 palmitic (> 14% wt). When using 2 g/L of molasses unsaturated fatty acids reached the highest portion (77%) than the control (61%). Specifically, all FAMEs have been quantitatively and qualitatively analyzed in order to improve biodiesel properties. The main characteristics of biodiesel obtainable from the algal lipids appeared in compliance with ASTM standards for unblended biodiesel and fulfilled European regulations (EN 14,214 and EN 590) for the quality of biodiesel. Owing the compliance of the corresponding biodiesel characteristics with international standards, a profitable biodiesel can be obtained under mixotrophic conditions triggered by the use of a food industry waste. Graphical abstract: [Figure not available: see fulltext.]

Arthrospira platensis holds promise for biotechnological applications due to its rapid growth and ability to produce valuable bioactive compounds like phycocyanin (PC). This study explores the impact of salinity and brewery wastewater (BWW) on the mixotrophic cultivation of A. platensis. Utilizing BWW as an organic carbon source and seawater (SW) for salt stress, we aim to optimize PC production and biomass composition. Under mixotrophic conditions with 2% BWW and SW, A. platensis showed enhanced biomass productivity, reaching a maximum of 3.70 g L−1 and significant increases in PC concentration. This study also observed changes in biochemical composition, with elevated protein and carbohydrate levels under salt stress that mimics the use of seawater. Mixotrophic cultivation with BWW and SW also influenced the FAME profile, enhancing the content of C16:0 and C18:1 FAMES. The purity (EP of 1.15) and yield (100 mg g−1) of PC were notably higher in mixotrophic cultures, indicating the potential for commercial applications in food, cosmetics, and pharmaceuticals. This research underscores the benefits of integrating the use of saline water with waste valorization in microalgae cultivation, promoting sustainability and economic efficiency in biotechnological processes.

The aviation industry is a “hard to electrify” sector with limited possibilities for alternative fuels such as green hydrogen. Therefore, there is a call for sustainable fuel alternatives which is driving intensive research into bio-jet fuels (BJF) that could be used in aviation, without revamping the aircraft fleets and the aviation infrastructures. This review evaluates the potential of photosynthetic microorganisms, focusing on the most challenging downstream processes, i.e. bio-oil production and its catalytic upgrade. The main bottlenecks of such processes are identified, and the most recent solutions, offered to overcome them, are critically reviewed. Finally, a statistical analysis of the key characteristics of current BJF derived from microalgae and cyanobacteria is presented, along with a discussion on their suitability for the aviation industry and the primary areas for improvement.