Salinity as an Abiotic Stressor for Eliciting Bioactive Compounds in Marine Microalgae.

This study investigated the impact of culture medium salinity (5-50 PSU) on the growth and maximum photochemical yield of photosystem II (/) and the composition of carotenoids, fatty acids, and bioactive substances in three marine microalgae (, , and ). The microalgae were photoautotrophically cultured in discontinuous mode in a single stage (S1) and a two-stage culture with salt shock (S2). A growth model was developed to link biomass productivity with salinity for each species.

Long-lasting biofouling formation on transparent fouling-release coatings for the construction of efficient closed photobioreactors.

In order to build an efficient closed-photobioreactor (PBR) in which biofouling formation is avoided, a non-toxic coating with high transparency is required, which can be applied to the interior surface of the PBR walls. Nowadays, amphiphilic copolymers are being used to inhibit microorganism adhesion, so poly(dimethylsiloxane)-based coatings mixed with poly(ethylene glycol)-based copolymers could be a good option. The 7 poly(dimethylsiloxane)-based coatings tested in this work contained 4% w/w of poly(ethylene glycol)-based copolymers.

Bioactives Overproduction through Operational Strategies in the Ichthyotoxic Microalga Culture.

The red tide-forming microalga has been associated with massive events of fish deaths, both wild and cultured. Culture conditions are responsible for the synthesis or accumulation of some metabolites with different interesting bioactivities. LC269919 strain was grown in a 10 L bubble column photobioreactor artificially illuminated with multi-coloured LED lights.

Adsorption Analysis of Exopolymeric Substances as a Tool for the Materials Selection of Photobioreactors Manufacture.

An improved method that allows the robust characterization of surfaces is necessary to accurately predict the biofouling formation on construction materials of photobioreactors (PBR). Exopolymeric substances (EPS), such as proteins and polysaccharides, have been demonstrated to present a similar behavior to cells in terms of surface adhesion. In this work, these EPS were used to optimize parameters, such as EPS concentration or adsorption time, to evaluate accurately the adsorption capacity of surfaces and, with it, predict the biofouling formation in contact with microalgae cultures.

Effect of Nitrogen, Phosphorous, and Light Colimitation on Amphidinol Production and Growth in the Marine Dinoflagellate Microalga .

The marine dinoflagellate microalga is a source of amphidinols, a fascinating group of polyketide metabolites potentially useful in drug design. However, grows slowly and produces these toxins in tiny amounts, representing a hurdle for large-scale production. Understanding dinoflagellate growth kinetics under different photobioreactor conditions is imperative for promoting the successful implementation of a full-scale integrated bioproduct production system.

The Isolation of Specialty Compounds from Biomass by Two-Step Solid-Phase and Liquid-Liquid Extraction.

The two main methods for partitioning crude methanolic extract from biomass were compared. The objective was to obtain three enriched fractions containing amphidinols (APDs), carotenoids, and fatty acids. Since the most valuable bioproducts are APDs, their recovery was the principal goal.

Influence of abiotic conditions on the biofouling formation of flagellated microalgae culture.

This work analyses the adhesion of flagellated microalgae to seven surfaces that have different water adhesion tension characteristics. and , were cultivated in batch and fed-batch mode at four nitrogen/phosphorus (N/P) ratios (from 1.29 to 70) and subjected to four irradiance levels (50, 100, 200 and 400 µE·s·m) at 23 °C.

Production of Amphidinols and Other Bioproducts of Interest by the Marine Microalga Unraveled by Nuclear Magnetic Resonance Metabolomics Approach Coupled to Multivariate Data Analysis.

This study assessed the feasibility of an NMR metabolomics approach coupled to multivariate data analysis to monitor the naturally present or stresses-elicited metabolites from a long-term (>170 days) culture of the dinoflagellate marine microalgae grown in a fiberglass paddlewheel-driven raceway photobioreactor. Metabolic contents, in particular, in two members of the amphidinol family, amphidinol A and its 7-sulfate derivative amphidinol B (referred as APDs), and other compounds of interest (fatty acids, carotenoids, oxylipins, etc.) were evaluated by altering concentration levels of the f/2 medium nutrients and daily mean irradiance.

NMR Metabolomics as an Effective Tool To Unravel the Effect of Light Intensity and Temperature on the Composition of the Marine Microalgae Isochrysis galbana.

NMR spectroscopy coupled with multivariate data analysis techniques was applied to obtain meaningful information about nontargeted metabolic changes on  Isochrysis galbana upon acclimation to different environmental conditions at indoor lab-scale. The effects of temperature (from 15 to 30 °C) and incident irradiance (from 250 to 1600 μmol m s) at a constant dilution rate of 0.3 h were evaluated.

Preparative Recovery of Carotenoids from Microalgal Biomass.

Carotenoids are widespread substances with important physiological roles, and some of them, such as lutein, astaxanthin, or vaucherioxanthin, are high-value products that can be used as high-quality food color and antioxidants, and some have an alleged role in the prevention of disorders such as AMD. Carotenoid extracts are currently obtained from plant sources, but microalgae have been demonstrated to be a competitive source likely to become an alternative. The extraction of carotenoids from microalgae possesses specific problems that arise from the different structure and composition of the source biomass.

Biofouling in photobioreactors for marine microalgae.

The economic and/or energetic feasibility of processes based on using microalgae biomass requires an efficient cultivation system. In photobioreactors (PBRs), the adhesion of microalgae to the transparent PBR surfaces leads to biofouling and reduces the solar radiation penetrating the PBR. Light reduction within the PBR decreases biomass productivity and, therefore, the photosynthetic efficiency of the cultivation system.

Simultaneous effect of temperature and irradiance on growth and okadaic acid production from the marine dinoflagellate Prorocentrum belizeanum.

Benthic marine dioflagellate microalgae belonging to the genus Prorocentrum are a major source of okadaic acid (OA), OA analogues and polyketides. However, dinoflagellates produce these valuable toxins and bioactives in tiny quantities, and they grow slowly compared to other commercially used microalgae. This hinders evaluation in possible large-scale applications.

Protein measurements of microalgal and cyanobacterial biomass.

The protein content of dry biomass of the microalgae Porphyridium cruentum, Scenedesmus almeriensis, and Muriellopsis sp. and of the cyanobacteria Synechocystis aquatilis and Arthrospira platensis was measured by the Lowry method following disruption of the cells by milling with inert ceramic particles. The measurements were compared with the Kjeldahl method and by elemental analysis.

Stability of carotenoids in Scenedesmus almeriensis biomass and extracts under various storage conditions.

Scenedesmus almeriensis biomass is a source of carotenoids, particularly lutein, and is considered to be promising as an alternative source to marigold. One key question concerning alternative sources of lutein is the loss of carotenoids that takes place between harvesting and processing, which in the case of marigold is frequently up to 50%. The work described here involved a study into the stability of the main carotenoids (lutein, violaxanthin, and beta-carotene), as well as other components, under different storage conditions.

New culture approaches for yessotoxin production from the dinoflagellate Protoceratium reticulatum.

Fed-batch and perfusion cultures were carried out in a traditional glass 2-L bioreactor with the toxic dinoflagellate Protoceratium reticulatum. The maximum cell concentration obtained was 2.3 x 105 cell.