Microalgae are sunlight-driven green cell factories for the production of potential bioactive products and biofuels. Nannochloropsis represents a genus of marine microalgae with high photosynthetic efficiency and can convert carbon dioxide to storage lipids mainly in the form of triacylglycerols and to the ω-3 long-chain polyunsaturated fatty acid eicosapentaenoic acid (EPA). Recently, Nannochloropsis has received ever-increasing interests of both research and public communities. This review aims to provide an overview of biology and biotechnological potential of Nannochloropsis, with the emphasis on lipid production. The path forward for the further exploration of Nannochloropsis for lipid production with respect to both challenges and opportunities is also discussed.

Fucoxanthin has been receiving ever-increasing interest due to its broad health beneficial effects. Currently, seaweeds are the predominant source of natural fucoxanthin. However, the disappointingly low fucoxanthin content has impeded their use, driving the exploration of alternative fucoxanthin producers. In the present study, thirteen diatom strains were evaluated with respect to growth and fucoxanthin production potential. Cyclotella cryptica (CCMP 333), which grew well for fucoxanthin production under both photoautotrophic and heterotrophic growth conditions, was selected for further investigation. The supply of nitrate and light individually or in combination were all found to promote growth and fucoxanthin accumulation. When transferring heterotrophic cultures to light, fucoxanthin responded differentially to light intensities and was impaired by higher light intensity with a concomitant increase in diadinoxanthin and diatoxanthin, indicative of the modulation of Diadinoxanthin Cycle to cope with the light stress. Taken together, we, for the first time, performed the screening of diatom strains for fucoxanthin production potential and investigated in detail the effect of nutritional and environmental factors on C. cryptica growth and fucoxanthin accumulation. These results provide valuable implications into future engineering of C. cryptica culture parameters for improved fucoxanthin production and C. cryptica may emerge as a promising microalgal source of fucoxanthin.

Extracellular polysaccharides (EPS) produced by marine microalgae have the potential to be used as antioxidants, antiviral agents, immunomodulators, and anti-inflammatory agents. Although the marine microalga Crypthecodinium cohnii releases EPS during the process of docosahexaenoic acid (DHA) production, the yield of EPS remains relatively low. To improve the EPS production, a novel mutagenesis of C. cohnii was conducted by atmospheric and room temperature plasma (ARTP). Of the 12 mutants obtained, 10 mutants exhibited significantly enhanced EPS yield on biomass as compared with the wild type strain. Among them, mutant M7 was the best as it could produce an EPS volumetric yield of 1.02 g/L, EPS yield on biomass of 0.39 g/g and EPS yield on glucose of 94 mg/g, which were 33.85%, 85.35% and 57.17% higher than that of the wild type strain, respectively. Results of the present study indicated that mutagenesis of the marine microalga C. cohnii by ARTP was highly effective leading to the high-yield production of EPS.

The key properties of microalgal biodiesel are largely determined by the composition of its fatty acid methyl esters (FAMEs). The gas chromatography (GC) based techniques for fatty acid analysis involve energy-intensive and time-consuming procedures and thus are less suitable for high-throughput screening applications. In the present study, a novel quantification method for microalgal fatty acids was established based on the near-infrared spectroscopy (NIRS) technique. The lyophilized cells of oleaginous Chlorella containing different contents of lipids were scanned by NIRS and their fatty acid profiles were determined by GC-MS. NIRS models were developed based on the chemometric correlation of the near-infrared spectra with fatty acid profiles in algal biomass. The optimized NIRS models showed excellent performances for predicting the contents of total fatty acids, C16:0, C18:0, C18:1 and C18:3, with the coefficient of determination (R²) being 0.998, 0.997, 0.989, 0.991 and 0.997, respectively. Taken together, the NIRS method established here bypasses the procedures of cell disruption, oil extraction and transesterification, is rapid, reliable, and of great potential for high-throughput applications, and will facilitate the screening of microalgal mutants and optimization of their growth conditions for biodiesel production.

This study investigated anaerobically digested swine wastewater (ADSW) as a nutrient source for Chlorella vulgaris FACHB-8 cultivation under mixotrophic conditions with carbon supplementation. The microalgal strain was grown in ADSW supplemented with six carbon sources, followed by concentration optimization. Under optimized conditions (20 g/L glucose), FACHB-8 demonstrated a high biomass productivity (271.31 mg/L/day) and a specific growth rate of 0.42 per day. The system achieved an 88.70% total nitrogen removal and an 82.93% total phosphorus removal. The biomass contained 45.59% lipids, 29.72% proteins, and 13.05% carbohydrates, with fatty acid methyl esters showing balanced proportions of saturated (50.77%) and unsaturated fatty acids (49.23%). These findings highlight the potential of glucose-based mixotrophic cultivation for simultaneous wastewater treatment, renewable biomass production, and value-added lipid production. This work proposes a scalable swine wastewater treatment system that synergizes bioremediation and renewable energy production via carbon-enhanced microalgae cultivation, offering a dual-functional strategy for sustainable livestock wastewater reuse.