Special Issue "Extraction, Exploitation and Application of Algae Biomass"

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: 28 February 2022.

Special Issue Editors

Prof. Dr. Juan Luis Gomez Pinchetti
E-Mail Website
Guest Editor
Spanish Bank of Algae (BEA), Institute of Oceanography and Global Change (IOCAG), University of Las Palmas de Gran Canaria, Muelle de Taliarte s/n, 35214 Telde, Canary Islands, Spain
Interests: physiology; biochemistry; transformation and potential applications of algal biomass produced under different cultivation approaches; including the development of biofiltration systems using algae. He has got a wide experience in cultivation, under controlled conditions, of marine macro-, microalgae, and cyanobacteria at different laboratory- and pilot-scale systems.
Prof. Dr. Francisco Gabriel Acién Fernández
E-Mail Website
Guest Editor
Department of Chemical Engineering, University of Almería, 04120 Almería, Spain
Interests: microalgae biotechnology; photosynthesis; sustainability; biomass production; waste valorization; agricultural products
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

In the last 25 years, the highest percentages of algal biomass produced and processed by the industry were mostly generated through cultivation activities. Previous overexploitation and, nowadays, control mechanisms in a scenario of climate change make natural populations difficult to exploit in a sustainable way. This fact drives to the necessity to develop algae culture techniques, at an industrial scale, mainly based on the use of sunlight, seawater and non-arable land.

New production efforts and developments are focused on techniques and systems that allow increasing biomass yields for both macro- and microalgae (including cyanobacteria) at the same time than improving biomass quality with industrial interest and potential. Under controlled conditions, activities related to species and strain selection based on growth performance, sustainable yields, biomass quality, downstream possibilities, including the concept of a biorefinery, security and/or traceability, together with the possibilities for wastewater nutrients and CO2 gases recycling, are being strongly considered to become key factors for the future success of industrial algae production.

This special issue on “Extraction, Exploitation and Application of Algae Biomass” seeks high quality works focusing on the latest novel advances related to algae production, biomass processed and industrial developments. Topics include, but are not limited to:

- Algae species and strains selection, characterization and potential applications;

- Cultivation improvements: biological and technical approaches;

- Bioremediation processes and circular economy by using algae;

- Algae as climate change mitigation tools;

- Developments on downstream processes and biorefinery;

- Applications and future possibilities

- The Nagoya protocol and the access and use of algae genetic resources

Prof. Dr. Juan Luis Gomez Pinchetti
Prof. Dr. Francisco Gabriel Acién Fernández
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Alga
  • applications, biomass
  • biotechnology
  • bioremediation
  • cultivation
  • downstream processes
  • macroalgae
  • microalgae
  • production

Published Papers (8 papers)

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Research

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Article
Study of Biocrudes Obtained via Hydrothermal Liquefaction (HTL) of Wild Alga Consortium under Different Conditions
Processes 2021, 9(9), 1494; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9091494 - 25 Aug 2021
Viewed by 608
Abstract
Microalga-based fuels are promising solutions for replacing fossil fuels. This feedstock presents several advantages such as fast growth in a harsh environment and an ability to trap gases emitted from industries, thus reducing global warming effects. An efficient way to convert harvested microalgae [...] Read more.
Microalga-based fuels are promising solutions for replacing fossil fuels. This feedstock presents several advantages such as fast growth in a harsh environment and an ability to trap gases emitted from industries, thus reducing global warming effects. An efficient way to convert harvested microalgae into biofuels is hydrothermal liquefaction (HTL), which yields an intermediate product called biocrude. In this study, the elemental and molecular compositions of 15 different HTL biocrudes were determined by means of different techniques. Wild algae were cultivated in an industrial environment with plant emissions as a carbon source in fresh or seawater. It was notably observed that the culture medium had an influence on the biochemical composition and mineral matter content of algae. Thus, seawater algae were characterized by larger amounts of carbohydrates and mineral matter than freshwater ones, which also affected the oil yields and the light and heavy fractions of biocrudes. Full article
(This article belongs to the Special Issue Extraction, Exploitation and Application of Algae Biomass)
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Article
Long-Term Cultivation of a Native Arthrospira platensis (Spirulina) Strain in Pozo Izquierdo (Gran Canaria, Spain): Technical Evidence for a Viable Production of Food-Grade Biomass
Processes 2021, 9(8), 1333; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9081333 - 30 Jul 2021
Viewed by 490
Abstract
Microalgae cultivation is a promising alternative to traditional agriculture in arid—semi-arid areas. The aim of this study is to assess the viability of long-term cultivation of native Arthrospira platensis in Gran Canaria. Maximum culture productivity (0.08 g/L/day) and optimal concentration range (0.6–0.9 g/L) [...] Read more.
Microalgae cultivation is a promising alternative to traditional agriculture in arid—semi-arid areas. The aim of this study is to assess the viability of long-term cultivation of native Arthrospira platensis in Gran Canaria. Maximum culture productivity (0.08 g/L/day) and optimal concentration range (0.6–0.9 g/L) were firstly determined in 8000 L raceway under a greenhouse. Afterwards, a stable productivity of 0.06 g/L/day (6.0 g/m2/day) was obtained by reusing the culture medium during 26 days of cultivation, with consistent biomass biochemical composition. Outdoor temperature and daily solar irradiation ranged between 17.9–30.7 °C and 79.2–274.8 W/m2, while culture pH and salinity were in the range 9.42–10.77 and 11.2–14.9 g/L, respectively. Protein (>60%), potassium (1.8 g/100 g) and C-phycocyanin (7.2%) content is in the high-range of commercial Spirulina, which makes BEA 1257B promising for food and extraction of natural pigments/antioxidants. The dried biomass complies with international standards for human consumption, because of low heavy metal content and no pathogens presence. Product quality can be improved by reducing ash (≃12%) and sodium (1.5%) content through biomass washing optimization and/or further dewatering step. Other microorganisms can be prevented by high alkaline conditions and mild chemical treatments. These results pave the way for a sustainable microalgae-based blue bioeconomy in the Canary Islands. Full article
(This article belongs to the Special Issue Extraction, Exploitation and Application of Algae Biomass)
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Article
Scaling-Up and Semi-Continuous Cultivation of Locally Isolated Marine Microalgae Tetraselmis striata in the Subtropical Island of Gran Canaria (Canary Islands, Spain)
Processes 2021, 9(8), 1326; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9081326 - 29 Jul 2021
Cited by 1 | Viewed by 552
Abstract
The goal of this study was to determine the feasibility of the large-scale cultivation of locally isolated Tetraselmis striata in different open ponds in Gran Canaria. The biomass productivities were 24.66 ± 0.53 kgDW in 32 days (28.9 t/ha/year) for 8000 L [...] Read more.
The goal of this study was to determine the feasibility of the large-scale cultivation of locally isolated Tetraselmis striata in different open ponds in Gran Canaria. The biomass productivities were 24.66 ± 0.53 kgDW in 32 days (28.9 t/ha/year) for 8000 L indoors, 42.32 ± 0.81 kgDW in 43 days (38.8 t/ha/year) for an 8000 L pond outdoors, and 54.9 ± 0.58 kgDW in 28 days (19.6 t/ha/year) for a 45,000 L pond outdoors. The photosynthetic efficiencies were 1.45 ± 0.03% for an 8000 L pond indoors, 1.95 ± 0.04% for 8000 L outdoors. and 1.10 ± 0.01% for a 45,000 L pond outdoors. The selected strain was fast-growing (µ = 0.21 day−1) and could be rapidly scaled up to 45,000 L; it formed healthy cultures that maintained high photosynthetic activity during long-term cultivation and provided stable biomass productivities, able to grow on urea, which acted as a cheap and effective grazer control. The obtained biomass is a good source of proteins and has an FA profile with a high content of some nutritionally important fatty acids: oleic, α-linolenic (ALA) and EPA. The high ash content in the biomass (>35%) can be reduced by the implementation of additional washing steps after the centrifugation of the culture. Full article
(This article belongs to the Special Issue Extraction, Exploitation and Application of Algae Biomass)
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Article
Role of Microalgae in the Recovery of Nutrients from Pig Manure
Processes 2021, 9(2), 203; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9020203 - 21 Jan 2021
Cited by 6 | Viewed by 1028
Abstract
Animal production inevitably causes the emission of greenhouse gases and the generation of large amounts of slurry, both representing a serious environmental problem. Photosynthetic microorganisms such as microalgae and cyanobacteria have been proposed as alternative strategies to bioremediate agricultural waste while consuming carbon [...] Read more.
Animal production inevitably causes the emission of greenhouse gases and the generation of large amounts of slurry, both representing a serious environmental problem. Photosynthetic microorganisms such as microalgae and cyanobacteria have been proposed as alternative strategies to bioremediate agricultural waste while consuming carbon dioxide and producing valuable biomass. The current study assessed the potential of the microalga Scenedesmus sp. to remove nutrients from piggery wastewater (PWW) and the influence of the microalga on the microbial consortia. Maximum N-NH4+ consumption was 55.3 ± 3.7 mg·L−1·day−1 while P-PO43− removal rates were in the range 0.1–1.9 mg·L−1·day−1. N-NH4+ removal was partially caused by the action of nitrifying bacteria, which led to the production of N-NO3. N-NO3 production values where lower when microalgae were more active. This work demonstrated that the photosynthetic activity of microalgae allows us to increase nutrient removal rates from PWW and to reduce the coliform bacterial load of the effluent, minimising both their environmental impact and health risks. Microalgae assimilated part of the N-NH4+ present in the media to produce biomass and did not to convert it into N-NO3 as in traditional processes. Full article
(This article belongs to the Special Issue Extraction, Exploitation and Application of Algae Biomass)
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Article
Green Synthesis of Copper Oxide Nanoparticles Using Protein Fractions from an Aqueous Extract of Brown Algae Macrocystis pyrifera
Processes 2021, 9(1), 78; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9010078 - 31 Dec 2020
Cited by 1 | Viewed by 1315
Abstract
Amongst different living organisms studied as potential candidates for the green synthesis of copper nanoparticles, algal biomass is presented as a novel and easy-to-handle method. However, the role of specific biomolecules and their contribution as reductant and capping agents has not yet been [...] Read more.
Amongst different living organisms studied as potential candidates for the green synthesis of copper nanoparticles, algal biomass is presented as a novel and easy-to-handle method. However, the role of specific biomolecules and their contribution as reductant and capping agents has not yet been described. This contribution reports a green synthesis method to obtain copper oxide nanoparticles (CuO-NPs) using separated protein fractions from an aqueous extract of brown algae Macrocystis pyrifera through size exclusion chromatography (HPLC-SEC). Proteins were detected by a UV/VIS diode array, time-based fraction collection was carried out, and each collected fraction was used to evaluate the synthesis of CuO-NPs. The characterization of CuO-NPs was evaluated by Dynamic Light Scattering (DLS), Z-potential, Fourier Transform Infrared (FTIR), Transmission Electron Microscope (TEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS) detector. Low Molecular Weight (LMW) and High Molecular Weight (HMW) protein fractions were able to synthesize spherical CuO-NPs. TEM images showed that the metallic core present in the observed samples ranged from 2 to 50 nm in diameter, with spherical nanostructures present in all containing protein samples. FTIR measurements showed functional groups from proteins having a pivotal role in the reduction and stabilization of the nanoparticles. The highly negative zeta potential average values from obtained nanoparticles suggest high stability, expanding the range of possible applications. This facile and novel protein-assisted method for the green synthesis of CuO-NPs may also provide a suitable tool to synthesize other nanoparticles that have different application areas. Full article
(This article belongs to the Special Issue Extraction, Exploitation and Application of Algae Biomass)
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Article
Potential Impact of Biodegradable Surfactants on Foam-Based Microalgal Cultures
Processes 2020, 8(12), 1640; https://0-doi-org.brum.beds.ac.uk/10.3390/pr8121640 - 12 Dec 2020
Cited by 2 | Viewed by 638
Abstract
Microalgae cultivation in liquid foams is a promising concept which requires the use of a surfactant as a foam stabilizing agent. The biodegradable character of a surfactant is a key aspect regarding its applicability in a liquid foam-bed photobioreactor (LF-PBR), since it might [...] Read more.
Microalgae cultivation in liquid foams is a promising concept which requires the use of a surfactant as a foam stabilizing agent. The biodegradable character of a surfactant is a key aspect regarding its applicability in a liquid foam-bed photobioreactor (LF-PBR), since it might influence microalgal growth and the stability of the foam-based cultivation. In this work, the effects of the biodegradable surfactants bovine serum albumin (BSA), Saponin and Tween 20 on the whole microbial community of microalgal cultures (i.e., microalgal and bacterial populations) were studied. The three surfactants enhanced bacterial and microalgal growth in non-axenic microalgal cultures, but they differed in their efficiency to sustain bacterial growth. In this sense, Saponin was proven to enhance the growth of S. obliquus-associated bacteria in microalgae-free cultures, and to sustain it even when other nutrients were lacking, suggesting that Saponin can be used as an energy and nutrients source by these bacteria. The degradation and consumption of Saponin by S. obliquus-associated bacteria was also confirmed by the foaming capacity decrease in Saponin-added bacterial cultures. The biodegradable character of BSA, Saponin and Tween 20 reduces their suitability to be used in a LF-PBR since they would not be able to maintain stable foaming. Full article
(This article belongs to the Special Issue Extraction, Exploitation and Application of Algae Biomass)
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Article
Optimisation of Protein Recovery from Arthrospira platensis by Ultrasound-Assisted Isoelectric Solubilisation/Precipitation
Processes 2020, 8(12), 1586; https://0-doi-org.brum.beds.ac.uk/10.3390/pr8121586 - 01 Dec 2020
Cited by 4 | Viewed by 612
Abstract
A response surface methodology was used to optimise the solubilisation and precipitation of proteins from the cyanobacterium Arthrospira platensis. Two separate experiments were designed and conducted in a sequential manner. Protein solubilisation was affected by pH, extraction time, and biomass to solvent ratio [...] Read more.
A response surface methodology was used to optimise the solubilisation and precipitation of proteins from the cyanobacterium Arthrospira platensis. Two separate experiments were designed and conducted in a sequential manner. Protein solubilisation was affected by pH, extraction time, and biomass to solvent ratio (p < 0.001). Although spray-drying and the osmotic shock suffered when resuspending the dried biomass into distilled water led to a certain degree of cell wall disruption, the amount of protein that could be solubilised without an additional disruption step was in the range 30–60%. Sequential extractions improved protein solubilisation by less than 5%. For this reason, a pre-treatment based on sonication (400 W, 24 kHz, 2 min) had to be used, allowing the solubilisation of 96.2% of total proteins. Protein precipitation was affected by both pH and extraction time (p < 0.001). The optimised precipitation conditions, which were pH 3.89 over 45 min, led to a protein recovery of 75.2%. The protein content of the extract was close to 80%, which could be further increased by using different purification steps. The proteins extracted could be used in the food industry as technofunctional ingredients or as a source of bioactive hydrolysates and peptides for functional foods and nutraceuticals. Full article
(This article belongs to the Special Issue Extraction, Exploitation and Application of Algae Biomass)
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Review

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Review
Variables Governing Photosynthesis and Growth in Microalgae Mass Cultures
Processes 2021, 9(5), 820; https://0-doi-org.brum.beds.ac.uk/10.3390/pr9050820 - 08 May 2021
Viewed by 621
Abstract
Since the 1950s, microalgae have been grown commercially in man-made cultivation units and used for biomass production as a source of food and feed supplements, pharmaceuticals, cosmetics and lately biofuels, as well as a means for wastewater treatment and mitigation of atmospheric CO [...] Read more.
Since the 1950s, microalgae have been grown commercially in man-made cultivation units and used for biomass production as a source of food and feed supplements, pharmaceuticals, cosmetics and lately biofuels, as well as a means for wastewater treatment and mitigation of atmospheric CO2 build-up. In this work, photosynthesis and growth affecting variables—light intensity, pH, CO2/O2 exchange, nutrient supply, culture turbulence, light/dark cell cycling, biomass density and culture depth (light path)—are reviewed as concerns in microalgae mass cultures. Various photosynthesis monitoring techniques were employed to study photosynthetic performance to optimize the growth of microalgae strains in outdoor cultivation units. The most operative and reliable techniques appeared to be fast-response ones based on chlorophyll fluorescence and oxygen production monitoring, which provide analogous results. Full article
(This article belongs to the Special Issue Extraction, Exploitation and Application of Algae Biomass)
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