Comparative Study Highlights the Potential of Spectral Deconvolution for Fucoxanthin Screening in Live Phaeodactylum tricornutum Cultures

Microalgal biotechnology shows considerable promise as a sustainable contributor to a broad range of industrial avenues. The field is however limited by processing methods that have commonly hindered the progress of high throughput screening, and consequently development of improved microalgal strains. We tested various microplate reader and flow cytometer methods for monitoring the commercially relevant pigment fucoxanthin in the marine diatom Phaeodactylum tricornutum. Based on accuracy and flexibility, we chose one described previously to adapt to live culture samples using a microplate reader and achieved a high correlation to HPLC (R2 = 0.849), effectively removing the need for solvent extraction. This was achieved by using new absorbance spectra inputs, reducing the detectable pigment library and changing pathlength values for the spectral deconvolution method in microplate reader format. Adaptation to 384-well microplates and removal of the need to equalize cultures by density further increased the screening rate. This work is of primary interest to projects requiring detection of biological pigments, and could theoretically be extended to other organisms and pigments of interest, improving the viability of microalgae biotechnology as a contributor to sustainable industry.

Recent Advancements and Future Perspectives of Microalgae-Derived Pharmaceuticals

Microalgal cells serve as solar-powered factories that produce pharmaceuticals, recombinant proteins (vaccines and drugs), and valuable natural byproducts that possess medicinal properties. The main advantages of microalgae as cell factories can be summarized as follows: they are fueled by photosynthesis, are carbon dioxide-neutral, have rapid growth rates, are robust, have low-cost cultivation, are easily scalable, pose no risk of human pathogenic contamination, and their valuable natural byproducts can be further processed. Despite their potential, there are many technical hurdles that need to be overcome before the commercial production of microalgal pharmaceuticals, and extensive studies regarding their impact on human health must still be conducted and the results evaluated. Clearly, much work remains to be done before microalgae can be used in the large-scale commercial production of pharmaceuticals. This review focuses on recent advancements in microalgal biotechnology and its future perspectives.

Microalgae as Sustainable Biofactories to Produce High-Value Lipids: Biodiversity, Exploitation, and Biotechnological Applications

Microalgae are often called “sustainable biofactories” due to their dual potential to mitigate atmospheric carbon dioxide and produce a great diversity of high-value compounds. Nevertheless, the successful exploitation of microalgae as biofactories for industrial scale is dependent on choosing the right microalga and optimum growth conditions. Due to the rich biodiversity of microalgae, a screening pipeline should be developed to perform microalgal strain selection exploring their growth, robustness, and metabolite production. Current prospects in microalgal biotechnology are turning their focus to high-value lipids for pharmaceutic, nutraceutic, and cosmetic products. Within microalgal lipid fraction, polyunsaturated fatty acids and carotenoids are broadly recognized for their vital functions in human organisms. Microalgal-derived phytosterols are still an underexploited lipid resource despite presenting promising biological activities, including neuroprotective, anti-inflammatory, anti-cancer, neuromodulatory, immunomodulatory, and apoptosis inductive effects. To modulate microalgal biochemical composition, according to the intended field of application, it is important to know the contribution of each cultivation factor, or their combined effects, for the wanted product accumulation. Microalgae have a vital role to play in future low-carbon economy. Since microalgal biodiesel is still costly, it is desirable to explore the potential of oleaginous species for its high-value lipids which present great global market prospects.

Biofixation of Air Emissions and Biomass Valorization – Evaluation of Microalgal Biotechnology

This research appraised the simultaneous biofixation of carbon dioxide (CO 2 ) and nitric oxides (NO x ) by microalgae species Chlorella vulgaris , Haematococcus pluvialis , and Scenedesmus subspicatus . The experimental design was established by five treatments with gas concentrations between control – 0.04% of CO 2 , 5 to 15% of CO 2 , and 30 to 100 ppm of NOx. Parameters such as pH, growth, productivity, lipids, protein, carbon/ nitrogen ratio, and astaxanthin were evaluated. For all species, the maximal growth was achieved with 5% of CO 2 and 30 ppm of NO x . Regarding protein content, for all the three species, better results were obtained at higher concentrations of CO 2 and NOx. These results prove the microalgae capacity for CO 2 and NO x biofixation and reuse of biomass as a source of high value-added products, such as lipids, proteins, and astaxanthin. These findings support the indication of these species for flue gas treatment process and use in biorefineries systems.

Microalgal Co-Cultivation Prospecting to Modulate Vitamin and Bioactive Compounds Production

Microalgal biotechnology is gaining importance. However, key issues in the pipeline from species selection towards large biomass production still require improvements to maximize the yield and lower the microalgal production costs. This study explores a co-cultivation strategy to improve the bioactive compounds richness of the harvested microalgal biomass. Based on their biotechnological potential, two diatoms (Skeletonema marinoi, Cyclotella cryptica) and one eustigmatophyte (Nannochloropsis oceanica) were grown alone or in combination. Concentrations of ten vitamins (A, B1, B2, B6, B12, C, D2, D3, E and H), carotenoids and polyphenols, together with total flavonoids, sterols, lipids, proteins and carbohydrates, were compared. Moreover, antioxidant capacity and chemopreventive potential in terms inhibiting four human tumor-derived and normal cell lines proliferation were evaluated. Co-cultivation can engender biomass with emergent properties regarding bioactivity or bioactive chemical profile, depending on the combined species. The high vitamin content of C. cryptica or N. oceanica further enhanced (until 10% more) when co-cultivated, explaining the two-fold increase of the antioxidant capacity of the combined C. cryptica and N. oceanica biomass. Differently, the chemopreventive activity was valuably enhanced when coupling the two diatoms C. cryptica and S. marinoi. The results obtained in this pilot study promote microalgal co-cultivation as a valuable strategy aiming to boost their application in eco-sustainable biotechnology.

Consumer Attitudes towards Microalgae Production and Microalgae-Based Agricultural Products: The Cases of Almería (Spain) and Livorno (Italy)

The production of microalgal biomass and products derived thereof for a wide variety of applications is a hot research topic, with the number of facilities being built and products and biologically active molecules launched into the market increasing every year. The aim of the current study was to identify the attitudes of citizens in Almería (Spain) and Livorno (Italy) towards the construction of a microalgae production plant and a biorefinery in their cities and also their opinions about the microalgae-based products that could be produced. Overall, in Almería (Spain), a NIMBY (not in my back yard) attitude towards the construction of a microalgal production facility and especially towards a microalgal biorefinery was observed, despite the strong microalgal industry in the region and the higher knowledge of citizens about microalgae. In both locations, but especially in Livorno (Italy), microalgae-based biostimulants, biofertilisers, and aquafeeds were well accepted. Proximity was the main factor affecting the acceptance of a microalgae producing facility. Consumer knowledge about microalgal biotechnology and the health and environmental benefits of this valuable raw material are scarce, and opinions are based on drivers other than knowledge. After gaining more knowledge about microalgal biorefineries, most of the responses in Almería (47%) and Livorno (61%) were more positive.

Photo-sequencing batch reactor with Klebsormidium nitens: a promising microalgal biotechnology for sustainable phosphorus management in WWTPs

This study aims at improving the existing algal-based wastewater treatment technologies by overcoming some of the major drawbacks of these systems such as large required land area, culture contamination and energy intensive algal harvesting. The experiments were carried out in an open photo-sequencing batch reactor (PSBR) at a laboratory scale for nearly two months. A specific strain ACUS00207 of the aero-terrestrial green microalga Klebsormidium nitens (Kützing) Lokhorst was used. The strain is native to Bulgaria and belongs to a species that has never been used before in suspended growth systems for wastewater treatment for phosphorus removal. The culture of Klebsormidium nitens showed promising results: phosphorus removal rates (PRRs) ranging from 0.4 to 1 mg TP L−1 d−1, efficient settling properties and resistance to culture contamination with native microalgae. On the basis of the observed phosphorus removal mechanism of ‘biologically mediated chemical precipitation/phosphorus precipitation’, an innovative working mode of the Sequencing Batch reactor (SBR) is suggested in regard to the potential for reduction of the Hydraulic Retention Time (HRT) and respectively the required land area.