Molybdenum disulfide nanoparticles concurrently stimulated biomass and ß-carotene accumulation in Dunaliella salina.

Molybdenum disulfide nanoparticles (MoS2 NPs) hold tremendous properties in wide domain of applications. In this study, the impact of MoS2 NPs was investigated on algal physiological and metabolic properties and a two-stage strategy was acquired to enhance the commercial potential of Dunaliella salina. With 50 µg/L of MoS2 NPs exposure, cellular growth and biomass production were promoted by 1.47- and 1.33-fold than that in control, respectively. MoS2 NPs treated cells were subject to high light intensity for 7 days after 30 days of normal light cultivation, which showed that high light intensity gradually increased ß-carotene content by 1.48-fold. Furthermore, analyses of primary metabolites showed that combinatorial approach significantly altered the biochemical composition of D. salina. Together, these findings demonstrated that MoS2 NPs at an optimum concentration combined with high light intensity could be a promising approach to concurrently enhance biomass and ß-carotene production in microalgae.

Physiological and molecular responses in halotolerant Dunaliella salina exposed to molybdenum disulfide nanoparticles.

Molybdenum disulfide nanoparticles (MoS2 NPs) has emerged as the promising nanomaterial with a wide array of applications in the biomedical, industrial and environmental field. However, the potential effect of MoS2 NPs on marine organisms has yet to be reported. In this study, the effect of MoS2 NPs on the physiological index, subcellular morphology, transcriptomic profiles of the marine microalgae Dunaliella salina was investigated for the first time. exhibited "doping-like" effects on marine microalgae; Growth stimulation was 193.55%, and chlorophyll content increased 1.61-fold upon the addition of 50 µg/L MoS2 NPs. Additionally, exposure to MoS2 NPs significantly increased the protein and carbohydrate content by 2.03- and 1.56-fold, respectively. The antioxidant system was activated as well to eliminate the adverse influence of reactive oxygen species (ROS). Transcriptomic analysis revealed that genes involved in porphyrin synthesis, glycolysis/gluconeogenesis, tricarboxylic acid cycle and DNA replication were upregulated upon MoS2 NPs exposure, which supports the mechanistic role of MoS2 NPs in improving cellular growth and photosynthesis. The "doping-like" effects on marine algae suggest that the low concentration of MoS2 NPs might change the rudimentary ecological composition in the ocean.

Ethanol induced jasmonate pathway promotes astaxanthin hyperaccumulation in Haematococcus pluvialis.

Haematococcus pluvialis is a main biological resource for the antioxidant astaxanthin production, however, potential modulators and molecular mechanisms underpinning astaxanthin accumulation remain largely obscured. We discovered that provision of ethanol (0.4%) significantly triggered the cellular astaxanthin content up to 3.85% on the 4th day of treatment. Amongst, 95% of the accumulated astaxanthin was esterified, particularly enriched with monoesters. Ultrastructural analysis revealed that ethanol altered cell wall structure and physiological properties. Antioxidant analyses revealed that astaxanthin accumulation offset the ethanol induced oxidative stress. Ethanol treatment reduced carbohydrates while increased lipids and jasmonic acid production. Transcriptomic analysis uncovered that ethanol orchestrated the expression of crucial genes involved in carotenogenesis, e.g. PSY, BKT and CRTR-b were significantly upregulated. Moreover, methyl jasmonic acid synthesis was induced and played a major role in regulating the carotenogenic genes. The findings uncovered the novel viewpoint in the intricate transcriptional regulatory mechanisms of astaxanthin biosynthesis.

Adaptive evolution of microalgal strains empowered by fulvic acid for enhanced polyunsaturated fatty acid production.

Microalgae have emerged as the potential source for value-added products such as polyunsaturated fatty acids (PUFAs). Metabolic engineering of multiple metabolic pathways has promoted eicosapentaenoic acid (EPA) production in microalgae, however, further improvement is warranted owing to the burgeoning demand. Here we improved the microalgal strains by adaptive evolution under hyposalinity treatment, which showed that 70% salinity potentiated the algae to enhance PUFAs. To exploit the maximal PUFA production potential of evolved strains, we subjected evolved algae to light, temperature and fulvic acid treatment. Amongst, fulvic acid (15 mg/L) enhanced growth and achieved the highest EPA content (13.9%) in the evolved diatom. Fulvic acid enhanced antioxidant potential and unprecedently governed the expression of PUFA and lipid biosynthetic genes. Collectively, this investigation demonstrates the efficacy of adaptive evolution empowered by fulvic acid and exemplifies a feasible strain improving strategy to harness the biotechnological potential of microalgae.