Detrimental effects of UV-A radiation on antioxidant capacity and photosynthetic efficiency on a tropical microalga.

Antioxidants are molecules able to neutralize reactive oxygen species with potential applications in the cosmetic or nutraceutical industries. Abiotic stressors, such as light intensity, ultraviolet (UV) radiation, or nutrient availability, can influence their production. In the perspective of optimizing and understanding the antioxidant capacity of microalgae, we investigated the effects of UV-A radiation on growth, and antioxidant and photosynthetic activities on Tetraselmis, a microalga genus known for its high antioxidant capacity.

The effects of CO-induced acidification on Tetraselmis biomass production, photophysiology and antioxidant activity: A comparison using batch and continuous culture.

A Tetraselmis sp. was selected for its antioxidant activity owing to its high lipid peroxidation inhibition capacity. With the aim to monitor culture conditions to improve antioxidant activity, effects of CO-induced acidification on Tetraselmis growth, elemental composition, photosynthetic parameters and antioxidant activity were determined.

A method to assess algicidal activity of microalgal extracts coupling microalgae produced in stirred closed photobioreactor operating in continuous with pulse amplitude modulated (PAM) fluorometry.

We describe in the present study a quick and reliable method based on chlorophyll a fluorescence to assess putative algicidal effect of different microalgal extracts. We couple microalgal production under chemostat cultivation mode to continuously produce a given microalgae species (e.g.

Effects of Nitrogen Availability on the Antioxidant Activity and Carotenoid Content of the Microalgae sp.

sp. was previously identified as a species of interest for its antioxidant properties owing to its high carotenoid content. In addition, nitrogen availability can impact biomass and specific metabolites' production of microalgae.

Impact of Light Intensity on Antioxidant Activity of Tropical Microalgae.

Twelve microalgae species isolated in tropical lagoons of New Caledonia were screened as a new source of antioxidants. Microalgae were cultivated at two light intensities to investigate their influence on antioxidant capacity. To assess antioxidant property of microalgae extracts, four assays with different modes of action were used: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-éthylbenzothiazoline-6-sulphonique) (ABTS), oxygen radical absorbance capacity (ORAC), and thiobabituric acid reactive substances (TBARS).

Cell weight kinetics simulation in chemostat and batch culture of the rhodophyte Porphyridium cruentum.

Experimental observations of cell size variations in the proliferating rhodophyte Porphyridium cruentum cultured under fully controlled conditions showed significant decreases from inoculation to a steady state in the chemostat with 0.23 d(-1) dilution rate and to a minimum in batch, dropping in size by ratios of over 10. To numerically simulate these variations, we assumed that the cell is made up of two categories of components that behave differently during the interphase and mitosis.

Swirling flow implementation in a photobioreactor for batch and continuous cultures of Porphyridium cruentum.

Light is the main limiting factor in photoautotrophic-intensive production of microorganisms, and improvement of its use is an important concern for photobioreactor design and operation. Swirling flows, which are known to improve mass and photon transfers, were applied to annular light chambers of a photobioreactor and studied by simulation and microalgal culture. Two hydrodynamic conditions were compared: axial flow generating poor radial mixing, and tangential flow generating three-dimensional swirling motion.