Maximization of cyanobacterial growth and cyanotoxin productivity

Cyanobacteria group comprises more than 2000 species of prokaryotic organisms and they are commonly named "blue-green algae", in spite of being nowadays classified as Gramnegative bacteria. The worldwide occurrence of hepatotoxic cyanobacterium Microcystis aeruginosa and the accumulation of its toxin microcystin, the most widespread cyanotoxin, have been responsible for several human deaths and various animal intoxication incidents. In recognition to its toxicity, the World Health Organization (WHO) and several national governments established guidelines and recommendation values for this toxin in water, which gave rise to an increasing demand for microcystin's analytical standards. These standards might be used either as laboratory standards in human and environmental risk assessment or as tools for molecular and cell biology studies. However, their availability is still limited due to constrains found in production and purification processes, which inflate the final price to values as high as 28000/mg. Thus, the optimization of cyanobacterial cultivation and toxin purification techniques is needed to decrease production cost of such high added-value product. Since the variation of cyanobacterial blooms toxicity is influenced by environmental factors, the aim of this project is to i) evaluate the effect of environmental factors on Microcystis aeruginosa LEGE 91094 growth and microcystin-LR accumulation; ii) develop cultivation strategies to optimize cyanobacteria growth and maximize toxin productivity; iii) optimize downstream processing steps in order to obtain high yields of cyanotoxin

Study of up- and downstream processes in Microcystis aeruginosa cultivation - One approach, two distinct objectives

BioTech 2017 and 7th Czech-Swiss Symposium with Exhibition[Excerpt] The cyanobacterium Microcystis aeruginosa and the accumulation of its cyanotoxin microcystin (MC) have been responsible for several human/animal deaths and intoxication incidents. Therefore, the World Health Organization established recommendation values for MC in water, givingrisetoanincreasingdemandforMC’s analytical standards to be used as laboratory standards both in human and environmental risk assessment studies. These Cyanotoxinsarealsoconsideredpromising anticancer/antitumor drugs as well as antifungal, antialgal and insecticide agents. Despite the interest, commercial MC availability is still limited due to constraints found in production, which inflate the final price to values as high as 28000 e/mg. [...]info:eu-repo/semantics/publishedVersio

Cultivation systems of Coelastrella sp. isolated from lichens collected in the north of Portugal

There is a growing interest towards finding new bioactive compounds from natural, safe and sustainable sources and extremophilic microalgae have emerged as one of the most promising options. Lichens are constituted by microalgae/cyanobacteria cells associated with a fungus that are subjected to especially extreme conditions, resulting in the production of a great variety of specific biologically active metabolites. However, lichens have not been considered so far as a potential commercial source of bioactive compounds mostly due to their extremely low growth rates. In this work microalgae of the genus Coelastrella sp were isolated from lichens collected in the northern region of Portugal and the optimal conditions for biomass productivity were identified: temperature of 18 ºC, pH 7 and light intensity of 250 m. Three cultivation systems were evaluated, namely the bubble column (BC), flat panel (FP) and split cylinder airlift (SCA) photobioreactors, in order to evaluate and compare their influence on the growth and productivity of microalgae. The BC photobioreactor showed the lowest biomass productivity (Pmax) and specific growth rate (max), and the biomass concentration reached by FP and SCA was, respectively, 14.4 and 35.4% higher than that of BC. The SCA presented the highest Pmax of 0.113 ± 0.019 g.L-1.d-1 and max of 0.187 ± 0.00913 d-1. These values are a very significant advance in otherwise very slow-growing cultures, and point at the possibility of using these strains in larger scale cultivation systems in the near future.info:eu-repo/semantics/publishedVersio

Optimization of Microcystis aeruginosa cell disruption to enhance microcystin extraction and purification processes

[Excerpt] Worldwide occurrence of cyanobacterium Microcystis aeruginosa and accumulation of its hepatotoxin microcystin (MC) have been responsible for several incidents, leading the World Health Organization to implement guideline values for this toxin in water thus boosting the demand for MC’s analytical standards. Furthermore, cyanotoxins are also considered promising anticancer/antitumor drugs as well as antifungal, antialgal and insecticide agents. Consequently, the U.S. Environmental Protection Agency has introduced cyanotoxins in its list of substances to be studied as a precursor to regulatory action between 2018 and 2020. [...]info:eu-repo/semantics/publishedVersio

Microalgae biomass as an alternative source of biocompounds: New insights and future perspectives of extraction methodologies

Microalgae have characteristics that make them unique and full of potential. Their capacity to generate interesting bioactive molecules can add value to various industrial applications. However, most of these valuable compounds are intracellular, which makes their extraction a major bottleneck. Conventional extraction methodologies have some drawbacks, such as low eco-friendly character, high costs and energy demand, long treatment times, low selectivity and reduced extraction yields, as well as degradation of extracted compounds. The gaps found for these methods demonstrate that emergent approaches, such as ohmic heating, pulsed electric fields, ionic liquids, deep eutectic solvents, or high-pressure processing, show potential to overcome the current drawbacks in the release and extraction of added-value compounds from microalgae. These new processing techniques can potentially extract a variety of compounds, making the process more profitable and applicable to large scales. This review provides an overview of the most important and promising factors to consider in the extraction methodologies applied to microalgae. Additionally, it delivers broad knowledge of the present impact of these methods on biomass and its compounds, raising the possibility of applying them in an integrated manner within a biorefinery concept.Vitor Sousa acknowledges the Portuguese Foundation for Science and Technology (FCT) for their fellowship UI/BD/151238/2021. This study was supported by the FCT under the scope of the strategic funding of UIDB/04469/2020 and UIDP/04469/2020 unit, by LABBELS – Associate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems (LA/P/0029/2020). This research work was supported by ALGAVALOR - Lisboa-01-0247-FEDER-035234, supported by Operational Programme for Competitiveness and Internationalization (COMPETE2020), Lisbon Portugal Regional Operational Programme (Lisboa 2020) and Algarve Regional Operational Programme (Algarve 2020) under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work was funded by NORTE2020 Funds through the SUPPORT SYSTEM FOR SCIENTIFIC AND TECHNOLOGICAL RESEARCH - “STRUCTURED R & D & I PROJECTS” - HORIZON EUROPE under the project NORTE-01-0145-FEDER-000070. Ricardo Pereira and Oscar Dias acknowledge FCT for the Assistant Research contract obtained under CEEC Individual 2017 and 2018, respectively.info:eu-repo/semantics/publishedVersio

Screening of key abiotic factors for biomass production of Pavlova gyrans

Microalgae biomass is an important source of bioactive compounds with commercial interest (e.g., polyunsaturated fatty acids, proteins, pigments) for several industrial sectors such as cosmetics, pharmaceutical, food, and feed. Known for their plasticity and high growth rates under different environments, a precise control of microalgae cultivation is of the utmost importance to maximize biomass productivity and its biochemical composition, reducing, at the same time, the production costs involved. Nutritional conditions and abiotic parameters (e.g., temperature, light) are well-documented in bibliography as the main responsible factors for significant variations in microalgae biomass productivities and bioactive compounds profile. The aim of this study was to evaluate the main culture variables impacting the biomass growth of marine microalga Pavlova gyrans, an interesting species commonly used as feed in aquaculture due to its biochemical profile, which presents high concentrations of polyunsaturated fatty acids (e.g., eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA)) and several valuable phytosterols and pigments (e.g., carotenoids). The study was carried out by the application of a Plackett-Burman design (PB) as a screening tool to identify the physicochemical factors that favour biomass productivities (p-value<0.1). Using PB, it was possible to assess the impact of 17 independent variables in the biomass productivity, namely the concentration of each nutrient of the growth medium (13 in total), as well as the salinity, airflow, inoculum size, and light intensity. Biomass productivity ranged from 72 to 256 mg ash-free dry weight (AFDW).L-1.d-1, while the maximum biomass produced ranged from 0.8 to 2.2 g AFDW.L-1.Light intensity (p-value<0.001) and NaNO3 concentration (p-value=0.001) were found to have a positive effect on this parameter. On the contrary, the use of higher concentrations of CuSO4.5H2O negatively affected the growth of P. gyrans (p-value=0.073).This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit. The author Filipe Maciel thanks to the FCT its financial grant (SFRH/BD/133005/2017). This work is funded by the European Regional Development Fund (ERDF) through the Competitiveness factors Operational program – COMPETE and by National Funds through the FCT under the project AgriFood XXI (NORTE- 01-0145-FEDER-000041). This research work was supported by ALGAVALOR - Lisboa-01-0247-FEDER-035234, supported by Operational Programme for Competitiveness and Internationalization (COMPETE2020), by Lisbon Portugal Regional Operational Programme (Lisboa 2020) and by Algarve Regional Operational Programme (Algarve 2020) under the Portugal 2020 Partnership Agreement, through the ERDF.info:eu-repo/semantics/publishedVersio

Assessment of synergistic interactions between environmental factors on Microcystis aeruginosa growth and microcystin production

The combined effect of four abiotic factors on Microcystis aeruginosa growth and toxin production was assessed by culturing the cyanobacterium under different light intensities (10190 mol photons·m 2·s 1), CO2 concentrations (010% (v/v)), temperatures (1540 °C), and pH values (6.59.5). Results indicate a significant influence caused by the synergistic effect of environmental factors over growth-related parameters and cyanobacteria toxicity. The combined use of low to medium light intensities (50120 mol photons·m 2·s 1) and CO2 concentration (16% v/v) led to higher cell concentrations, while specific growth rate and biomass productivity were favoured by medium to high light intensities (110190 mol photons·m 2·s 1), CO2 concentrations (49.5% v/v) and temperatures (2939 °C). Regarding microcystin (MC) production, higher concentrations were obtained at low light intensities and low CO2 concentrations while approximately 2000-fold lower MC concentrations were achieved by simultaneous use of high values of light intensity, CO2 concentration and temperature.info:eu-repo/semantics/publishedVersio

Monitoring and mapping of intertidal macroalgae using low-cost geospatial automated techniques

The global extent of macroalgae is declining with important consequences on marine biodiversity and ecosystem processes. Tracking the status and trends of macroalgal cover is, therefore, an emerging priority for ocean and coastal management. A remote sensing technique combining UAVs surveys with in situ data acquisition was developed to map intertidal macroalgae from rocky shores in a marine protected area, the Atlantic Islands of Galicia National Park (Illas Cíes, NW Spain). The classifcation by groups (brown and green macroalgae) achieved a good precision. A more precise classifcation would be achieved by focusing on those spectral bands where the highest diferences between species appeared.Peer Reviewe

Combined effect of light intensity and CO2 concentration on Microcystis aeruginosa growth

[Excerpt] Worldwide occurrence of hepatotoxic cyanobacterium Microcystis aeruginosa and the accumulation of its toxin (microcystin), have been responsible for several human deaths and animal intoxication incidents. In recognition to its toxicity, the WHO and national governments established recommendation values for this toxin in water, which gave rise to an increasing demand for microcystin's analytical standards. These standards might be used either as laboratory standards in human and environmental risk assessment or as tools for molecular and cell biology studies. However, their availability is limited due to constraints found in production and purification processes, which inflate the final price to values as high as 28000€/mg. [...

Enhancing extraction of food-grade pigments from the microalgae Chlorella Vulgaris through application of ohmic heating

[Excerpt] Introduction: The use of ohmic heating (OH) with the associated non-thermal effects due to the presence of an electrical field and frequency, has been suggested for extraction of compounds from biological matrices. Microalgae are considered as a very valuable source of compounds of interest for food sector (i.e. pigments, lipids, carbohydrates, and proteins) and the selection of extraction technique to recover these compounds is very challenging due to the intrinsic nature of the microalgae cell walls, which limits the mass transfer through it. The main objective of this study is to investigate the effects of OH on the extraction of pigmented solutes from Chlorella vulgaris. [...