Title: Microalgae-Based Biofuels and Bioproducts, 1st Edition
Editors: Raul Muñoz Cristina Gonzalez-Fernandez (55 EUALGAE COST Action participants from 18 different countries listed among the authors)
Microalgae-Based Biofuels and Bioproducts: From Feedstock Cultivation to End Products compiles contributions from authors from different areas and backgrounds who explore the cultivation and utilization of microalgae biomass for sustainable fuels and chemicals.
With a strong focus in emerging industrial and large scale applications, the book summarizes the new achievements in recent years in this field by critically evaluating developments in the field of algal biotechnology, whilst taking into account sustainability issues and techno-economic parameters. It includes information on microalgae cultivation, harvesting, and conversion processes for the production of liquid and gaseous biofuels, such as biogas, bioethanol, biodiesel and biohydrogen. Microalgae biorefinery and biotechnology applications, including for pharmaceuticals, its use as food and feed, and value added bioproducts are also covered.
Readership: Researchers, professionals and graduate students in energy engineering, chemical engineering, biotechnology, environmental engineering and industrial engineering working with algal biofuels and bioproducts.
Title: Evolution and structural diversity of metacaspases
Authors: Klemencic, M., Funk, C.
Publication: Journal of Experimental Botany, Volume 70, Issue 7, Pages 2039–2047
Published: 15 March 2019
Caspases are metazoan proteases, best known for their involvement in programmed cell death in animals. In higher plants genetically controlled mechanisms leading to the selective death of individual cells also involve the regulated interplay of various types of proteases. Some of these enzymes are structurally homologous to caspases and have therefore been termed metacaspases. In addition to the two well-studied metacaspase variants found in higher plants, type I and type II, biochemical data have recently become available for metacaspases of type III and metacaspase-like proteases, which are present only in certain algae. Although increasing in vitro and in vivo data suggest the existence of further sub-types, a lack of structural information hampers the interpretation of their distinct functional properties. However, the identification of key amino acid residues involved in the proteolytic mechanism of metacaspases, as well as the increased availability of plant genomic and transcriptomic data, is increasingly enabling in-depth analysis of all metacaspase types found in plastid-containing organisms. Here, we review the structural distribution and diversification of metacaspases and in doing so try to provide comprehensive guidelines for further analyses of this versatile family of proteases in organisms ranging from simple unicellular species to flowering plants.
Title: Phylogenetic distribution and diversity of bacterial pseudo-orthocaspases underline their putative role in photosynthesis
Authors: Klemencic, M., Asplund-Samuelsson, J., Dolinar, M., Funk, C.
Publication: Frontiers in Plant Science, March 2019, Volume 10, Article 293
Published: 14 March 2019
Orthocaspases are prokaryotic caspase homologs – proteases, which cleave their substrates after positively charged residues using a conserved histidine – cysteine (HC) dyad situated in a catalytic p20 domain. However, in orthocaspases pseudo-variants have been identified, which instead of the catalytic HC residues contain tyrosine and serine, respectively. The presence and distribution of these presumably proteolytically inactive p20-containing enzymes has until now escaped attention. We have performed a detailed analysis of orthocaspases in all available prokaryotic genomes, focusing on pseudo-orthocaspases. Surprisingly we identified type I metacaspase homologs in filamentous cyanobacteria. While genes encoding pseudo-orthocaspases seem to be absent in Archaea, our results show conservation of these genes in organisms performing either anoxygenic photosynthesis (orders Rhizobiales, Rhodobacterales, and Rhodospirillales in Alphaproteobacteria) or oxygenic photosynthesis (all sequenced cyanobacteria, except Gloeobacter, Prochlorococcus, and Cyanobium). Contrary to earlier reports, we were able to detect pseudo-orthocaspases in all sequenced strains of the unicellular cyanobacteria Synechococcus and Synechocystis. In silico comparisons of the primary as well as tertiary structures of pseudo-p20 domains with their presumably proteolytically active homologs suggest that differences in their amino acid sequences have no influence on the overall structures. Mutations therefore affect most likely only the proteolytic activity. Our data provide an insight into diversification of pseudo-orthocaspases in Prokaryotes, their taxa-specific distribution, and allow suggestions on their taxa-specific function.
Title: Elucidating the symbiotic interactions between a locally isolated microalga Chlorella vulgaris and its co-occurring bacterium Rhizobium sp. in synthetic municipal wastewater
Authors: L. Ferro, M. Colombo, E. Posadas, C. Funk, R. Muñoz
Publication: Journal of Applied Phycology, 2019
Published on-line: 02 February 2019
Co-cultivation of microalgae and bacteria during municipal wastewater treatment can boost carbon and nutrient recovery as a result of their synergistic interactions. The symbiotic relationships between the locally isolated microalga Chlorella vulgaris and the bacterium Rhizobium sp., co-isolated from municipal wastewater, were investigated batchwise under photoautotrophic, heterotrophic, and mixotrophic conditions in a synthetic municipal wastewater medium. During photoautotrophic growth in BG11 medium, photosynthetic algal oxygenation and organic carbon production supported bacterial activity but no significant beneficial effects on microalgal growth were observed. In synthetic wastewater, a twofold higher biomass concentration was achieved in the axenic algal culture compared with the co-culture under heterotrophic conditions, suggesting a competition for nutrients. A comparable carbon removal was observed in all cultures (83–79% TOC), but a faster nitrogen consumption (59% TN) and complete phosphate assimilation (100% TP) was only achieved in the co-culture. A positive synergistic relationship was found under mixotrophic conditions, clearly supported by an in situ O2/CO2 exchange between the microorganisms. This mutualism led to a threefold higher biomass production with a 13-fold higher fatty acid content compared with the axenic algal culture, as well as a superior wastewater treatment performance (+ 58% TOC, + 41% TN and + 44% TP). The co-cultivation of C. vulgaris and Rhizobium is therefore suggested as a potential microbial consortium for a cost-efficient biomass generation during municipal wastewater reclamation, especially under mixotrophic conditions.
Title: Microalgal Bioactive Compounds Including Protein, Peptides, and Pigments: Applications, Opportunities, and Challenges During Biorefinery Processes. In: Novel Proteins for Food, Pharmaceuticals and Agriculture: Sources
Authors: Maria Hayes, Leen Bastiaens, Luisa Gouveia, Spyros Gkelis, Hanne Skomedal, Kari Skjanes, Patrick Murray, Marco García‐Vaquero, Muge Isleten Hosoglu, John Dodd, Despoina Konstantinou, Ivo Safarik, Graziella Chini Zittelli, Vytas Rimkus, Victόria del Pino, Koenraad Muylaert, Christine Edwards, Morten Laake, Joana Gabriela Laranjeira da Silva, Hugo Pereira, Joana Abelho
Publication: Applications and Advances (Hayes,M., Ed.), John Wiley and Sons, Ltd., 2019, pp. 239-255
First published: 03 October 2018
Microalgae accumulate a variety of compounds that form the basis for potential marketable products as whole cell biomass or as fractions after an extraction process. A cascading biorefinery approach aims at recovering and separating multiple algae compounds to valorise the complete biomass and to improve the economics of the value chain. This chapter discusses the extraction, characterisation, and current and potential applications, markets, and legislation surrounding the use of microalgal proteins as food, feed, and functional food products and ingredients.
Title: Effect of Increased Temperature on Native and Alien Nuisance Cyanobacteria from Temperate Lakes: An Experimental Approach
Authors: Savadova K., Mazur-Marzec H., Karosienė J., Kasperovičienė J., Vitonytė I., A. Torúnska-Sitarz, Koreivienė J.
Publication: Toxins 2018, Volume 10, Issue 11, 445.
Published: 30 October 2018
In response to global warming, an increase in cyanobacterial blooms is expected. In this work, the response of two native species of Planktothrix agardhii and Aphanizomenon gracile, as well as the response of two species alien to Europe—Chrysosporum bergii and Sphaerospermopsis aphanizomenoides—to gradual temperature increase was tested. The northernmost point of alien species distribution in the European continent was recorded. The tested strains of native species were favoured at 20–28 °C. Alien species acted differently along temperature gradient and their growth rate was higher than native species. Temperature range of optimal growth rate for S. aphanizomenoides was similar to native species, while C. bergii was favoured at 26–30 °C but sensitive at 18–20 °C. Under all tested temperatures, non-toxic strains of the native cyanobacteria species prevailed over the toxic ones. In P. agardhii, the decrease in concentration of microcystins and other oligopeptides with the increasing temperature was related to higher growth rate. However, changes in saxitoxin concentration in A. gracile under different temperatures were not detected. Accommodating climate change perspectives, the current work showed a high necessity of further studies of temperature effect on distribution and toxicity of both native and alien cyanobacterial species.
Title: Nutrients utilization and contaminants removal. A review of two approaches of algae and cyanobacteria in wastewater
Authors: Cuellar-Bermudez Sara P., Gibran S. Aleman-Nava, Rashmi Chandra, J. Saul Garcia-Perez, Jose R. Contreras-Angulo, Giorgos Markou, Koenraad Muylaert, Bruce E. Rittmann, and Roberto Parra-Saldivar
Publication: Algal Research, Volume 24, Part B, June 2017, Pages 438-449
Published: September 2016
The detection of new pollutants, stricter environmental regulations, and advancements in treatment technologies are driving improvements in bioprocesses for treating wastewater. Specifically, special concern is being placed on phosphorus and nitrogen forms, which spur eutrophication of water bodies, and emerging micropollutants such as pharmaceuticals and person-care products. Algae and cyanobacteria cultivation requirements include water and nutrient sources that currently are supplied by fertilizers, which provide poor sustainability and economics. Using wastewater as a source of nitrogen and phosphorus represents an attractive option to cultivate microalgae simultaneous with contaminant removal. Phycoremediation refers to the assimilation or disintegration of organic and inorganic compounds (carbon, nitrogen, or phosphorus), metals, and emerging contaminants in wastewater by microalgae – algae and cyanobacteria. In addition, added value comes when the microalgae are harvested to become feedstock for biofuels such as biogas. Although promising studies have been published for algal growth in wastewater while simultaneously removing contaminants, limitations in the scale-up process still have to be addressed. In this work, we summarize biological mechanisms by which nutrients and contaminants are removed by microalgae. We specifically address the interactions that the microalgae have with other microorganisms and the production of extracellular polymeric substances, a mechanism well known in the literature, but hardly studied in microalgae. Finally, we discuss different strategies reported to improve the scale up of microalgae cultivation in wastewater.
Title: Advanced nutrient removal from surface water by a consortium of attached microalgae and bacteria: A review
Authors: Junzhuo Liu, Yonghong Wu, Chenxi Wu, Koenraad Muylaert, Wim Vyverman, Han-Qing Yu, Raúl Muñoz, Bruce Rittmann
Publication: Bioresource Technology, Volume 241, Pages 1127-1137
Published: October 2017
Innovative and cost-effective technologies for advanced nutrient removal from surface water are urgently needed for improving water quality. Conventional biotechnologies, such as ecological floating beds, or constructed wetlands, are not effective in removing nutrients present at low-concentration. However, microalgae-bacteria consortium is promising for advanced nutrient removal from wastewater. Suspended algal-bacterial systems can easily wash out unless the hydraulic retention time is long, attached microalgae-bacteria consortium is more realistic. This critical review summarizes the fundamentals and status of attached microalgae-bacteria consortium for advanced nutrient removal from surface water. Key advantages are the various nutrient removal pathways, reduction of nutrients to very low concentration, and diversified photobioreactor configurations. Challenges include poor identification of functional species, poor control of the community composition, and long start-up times. Future research should focus on the selection and engineering of robust microbial species, mathematical modelling of the composition and functionality of the consortium, and novel photobioreactor configurations.
Title: CO2 utilization in the production of biomass and biocompounds by three different microalgae
Authors: Joana Assuncao, Ana Paula Batista, Joao Manoel, Teresa Lopes da Silva, Paula Marques, Alberto Reis, Luisa Gouveia
Publication: Eng. Life Sci. 2017, 17, 1126-1135
Published: 24 July 2017
The atmospheric CO2 increase is considered the main cause of global warming. Microalgae are photosynthetic microorganisms that can help in CO2 mitigation and at the same time produce value‐added compounds. In this study, Scenedesmus obliquus, Chlorella vulgaris, and Chlorella protothecoides were cultivated under 0.035 (air), 5 and 10% (v/v) of CO2 concentrations in air to evaluate the performance of the microalgae in terms of kinetic growth parameters, theoretical CO2 biofixation rate, and biomass composition. Among the microalgae studied, S. obliquus presented the highest values of specific growth rate (μ = 1.28 d−1), maximum productivities (Pmax = 0.28 g L−1d−1), and theoretical CO2 biofixation rates (0.56 g L−1d−1) at 10% CO2. The highest oil content was found at 5% CO2, and the fatty acid profile was not influenced by the concentration of CO2 in the inflow gas mixture and was in compliance with EN 14214, being suitable for biodiesel purposes. The impact of the CO2 on S. obliquus cells’ viability/cell membrane integrity evaluated by the in‐line flow cytometry is quite innovative and fast, and revealed that 86.4% of the cells were damaged/permeabilized in cultures without the addition of CO2.
Title: Structural and functional diversity of caspase homologues in non-metazoan organisms
Authors: Marina Klemenčič, Christiane Funk
Publication: Protoplasma, January 2018, Volume 255, Issue 1, pp 387–397
Published: 25 July 2017
Caspases, the proteases involved in initiation and execution of metazoan programmed cell death, are only present in animals, while their structural homologues can be found in all domains of life, spanning from simple prokaryotes (orthocaspases) to yeast and plants (metacaspases). All members of this wide protease family contain the p20 domain, which harbours the catalytic dyad formed by the two amino acid residues, histidine and cysteine. Despite the high structural similarity of the p20 domain, metacaspases and orthocaspases were found to exhibit different substrate specificities than caspases. While the former cleave their substrates after basic amino acid residues, the latter accommodate substrates with negative charge. This observation is crucial for the re-evaluation of non-metazoan caspase homologues being involved in processes of programmed cell death. In this review, we analyse the structural diversity of enzymes containing the p20 domain, with focus on the orthocaspases, and summarise recent advances in research of orthocaspases and metacaspases of cyanobacteria, algae and higher plants. Although caspase homologues were initially proposed to be involved in execution of cell death, accumulating evidence supports the role of metacaspases and orthocaspases as important contributors to cell homeostasis during normal physiological conditions or cell differentiation and ageing.
Title: Type III metacaspases: calcium‐dependent activity proposes new function for the p10 domain
Authors: Marina Klemenčič, Christiane Funk
Publication: New Phytologist, Volume 218, Issue 3, May 2018, Pages 1179-1191
Published: 23 June 2017
Title: Evaluation of Marine Microalga Diacronema vlkianum Biomass Fatty Acid
Assimilation in Wistar Rats
Authors: Cristina de Mello-Sampayo, Angela Paterna, Ambra Polizzi, Diana Duarte, Irineu Batista, Rui Pinto, Patrícia Gonçalves, Anabela Raymundo, Ana P. Batista, Luísa Gouveia, Beatriz Silva-Lima and Narcisa M. Bandarra
Publication: Molecules 2017, 22(7), 1097
Published: 1 July 2017
Diacronema vlkianum is a marine microalgae for which supposed health promoting effects have been claimed based on its phytochemical composition. The potential use of its biomass as health ingredient, including detox-shakes, and the lack of bioavailability studies were the main concerns. In order to evaluate the microalgae-biomass assimilation and its health-benefits, single-dose (CD1-mice) studies were followed by 66-days repeated-dose study in Wistar rats with the highest tested single-dose of microalgae equivalent to 101 mg/kg eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA). Microalgae-supplementation modulated EPA and docosapentaenoic acid enrichment at arachidonic acid content expenditure in erythrocytes and liver, while increasing EPA content of heart and adipose tissues of rats. Those fatty acid (FA) changes confirmed the D. vlkianum-biomass FA assimilation. The principal component analyses discriminated brain from other tissues, which formed two other groups (erythrocytes, liver, and heart separated from kidney and adipose tissues), pointing to a distinct signature of FA deposition for the brain and for the other organs. The improved serum lipid profile, omega-3 index and erythrocyte plasticity support the cardiovascular benefits of D. vlkianum. These results bolster the potential of D. vlkianum-biomass to become a “heart-healthy” food supplement providing a safe and renewable source of bioavailable omega-3 FA.
Title: Effect of ammonia on the photosynthetic activity of Arthrospira and Chlorella: a study on chlorophyll fluorescence and electron transport
Authors: Markou Giorgos, Orily Depraetere, and Koenraad Muylaert
Publication: Algal Research, Volume 16, June 2016, Pages 449-457
Published: 23 April 2016
Although ammoniacal nitrogen is the preferred nitrogen source for microalgae/cyanobacteria, at elevated concentrations and high pH values it may negatively impact photosynthesis and growth. Chlorophyll (Chl) fluorescence analysis is a useful tool to monitor the influence of various stress conditions on the photosynthetic activity of plants or microalgae/cyanobacteria. In this study, we investigated the effect of ammoniacal nitrogen on Chl fluorescence in microalgae/cyanobacteria. Chl fluorescence analysis revealed that the parameters related to flux ratios and specific energy fluxes of photochemistry were gradually inhibited as the free ammonia (FA) concentration increased. Photosynthetic electron transport activity was measured using artificial electron acceptors, donors or inhibitors. These analyses suggest that ammonia has multiple impacts on the photosynthetic apparatus; photosystems I (PSI) and II (PSII), the electron transport chain, the oxygen-evolution complex (OEC) as well the dark respiration were gradually inhibited by increasing FA concentration. At high FA concentration, the PSI/PSII activity increased, suggesting that PSI was more tolerant to FA than PSII. Non-photochemical quenching (NPQ) decreased to zero at elevated FA concentrations. The Chl fluorescence data obtained in the presence of DCMU (diuron) suggest that the decrease of NPQ under ammonia inhibition/toxicity is due to the increase of PSI/PSII activity. The rapid response of Chl fluorescence transients to increases in FA may allow one to use pulse amplitude modulation (PAM) fluorescence as a tool to monitor ammonia inhibition/toxicity in cultures of microalgae/cyanobacteria.
Title: Applying raw poultry litter leachate for the cultivation of Arthrospira platensis and Chlorella vulgaris
Authors: Markou, Giorgos, Dimitris Iconomou, and Koenraad Muylaert
Publication: Algal Research, Volume 13, January 2016, Pages: 79-84.
Published: 7 December 2015
In the present paper, the use of raw poultry litter (PL) as a nutrient source for the cultivation of Arthrospira platensis and Chlorella vulgaris was investigated. PL was added to acid solution (62.5 mM H2SO4) for the extraction of nutrients contained in PL. After settling, the supernatant, called PL leachate (PLL) was diluted 25 ×, 20 ×, 15 ×, and 10 × and used as a medium for the cultivation of A. platensis and C. vulgaris. A. platensis could not survive in 15 × and 10 × diluted leachate and while in 20 × and 25 × dilutions the biomass production was only half of that in a control medium (Zarrouk). The biomass composition had a high carbohydrate content (37–44%), which suggests that A. platensis was stressed due to nutrient limitation. C. vulgaris grew well in PLL-based media and the biomass production was higher than in the control medium (BG-11). Biomass composition of C. vulgaris in PLL-based media had lower protein content and higher carbohydrate and lipid content than in the control medium. The overall process for producing microalgal biomass from PL that we propose includes: (i) acid extraction of nutrients through the generation of PL leachate (PLL), (ii) indoor PL composting and recovery of stripped ammonia and CO2, and (iii) use of recovered ammonia and CO2 along with the PLL for the cultivation of microalgae and cyanobacteria for the production of biomass.
Title: Isolation of a euryhaline microalgal strain, Tetraselmis sp. CTP4, as a robust feedstock for biodiesel production
Authors: Hugo Pereira, Katkam N. Gangadhar, Peter S. C. Schulze, Tamára Santos, Carolina Bruno de Sousa, Lisa M. Schueler, Luísa Custódio, F. Xavier Malcata, Luísa Gouveia, João C. S. Varela & Luísa Barreira
Publication: Scientific Reports volume 6, Article number: 35663 (2016)
Published: 21 October 2016
Bioprospecting for novel microalgal strains is key to improving the feasibility of microalgae-derived biodiesel production. Tetraselmis sp. CTP4 (Chlorophyta, Chlorodendrophyceae) was isolated using fluorescence activated cell sorting (FACS) in order to screen novel lipid-rich microalgae. CTP4 is a robust, euryhaline strain able to grow in seawater growth medium as well as in non-sterile urban wastewater. Because of its large cell size (9–22 μm), CTP4 settles down after a six-hour sedimentation step. This leads to a medium removal efficiency of 80%, allowing a significant decrease of biomass dewatering costs. Using a two-stage system, a 3-fold increase in lipid content (up to 33% of DW) and a 2-fold enhancement in lipid productivity (up to 52.1 mg L−1 d−1) were observed upon exposure to nutrient depletion for 7 days. The biodiesel synthesized from the lipids of CTP4 contained high levels of oleic acid (25.67% of total fatty acids content) and minor amounts of polyunsaturated fatty acids with ≥4 double bonds (<1%). As a result, this biofuel complies with most of the European (EN14214) and American (ASTM D6751) specifications, which commonly used microalgal feedstocks are usually unable to meet. In conclusion, Tetraselmis sp. CTP4 displays promising features as feedstock with lower downstream processing costs for biomass dewatering and biodiesel refining.
Title: Effect of Arthrospira platensis on the Shelf Life, Sensorial and Rheological Properties of strudel
Authors: KIANOUSH KHOSRAVI-DARANI, ZAHRA GHOLAMI, LUISA GOUVEIA
Publication: Romanian Biotechnological Letters 22/1 (2017) 12250–12258
Arthrospira platensis microalga is widely used in the food industry due to its nutritional value such as having high protein content, vitamins, essential amino acids, minerals and antimicrobial properties that inhibit the growth of mold and yeast. This study aimed to evaluate the effect of the addition of dried microalga at different levels (0, 0.5, 1 and 1.5% w/w) on the technological, sensorial, and rheological properties (texture and
color), as well as on the stability and the nutritional value of strudel. Results showed that the protein content of the enriched strudel was higher than control (p< 0.05) while its peroxide value reduced (p<0.01). Colorimetric analysis also showed that within 45 days, the color stability of enriched strudel samples was higher than control
(p<0.05). Results from sensorial analysis done by 10 panelists indicated that addition of powdered Arthrospira results in a brittle strudel and 0.5 and 1% fortification achieved the most popular preferences. The overall acceptance results showed that the best strudel can be obtained by adding 0.5 to 1 % Arthrospira platensis, which in addition to the improvement of the sensorial and rheological properties, also has antimicrobial properties that inhibit the growth of yeasts and molds.
Title: Scenedesmus obliquus mediated brewery wastewater remediation and
CO2 biofixation for green energy purposes
Authors: Alice Ferreira, Belina Ribeiro, Paula A.S.S. Marques, Ana F. Ferreira, Ana Paula Dias, Helena M. Pinheiro, Alberto Reis, Luisa Gouveia
Publication: Journal of Cleaner Production 165 (2017) 1316–1327
Published: Available online 31 July 2017
Microalgae can be used for wastewater bioremediation with simultaneous CO2 biofixation producing valuable biomass.
Wastewater from a brewery was treated using the Scenedesmus obliquus microalga in bubble-column photobioreactors (PBRs). The PBRs were fed with ambient air and the effect of a 10% (v/v) brewery CO2 supplement was studied. The PBRs were inoculated and a range of mean hydraulic residence time (HRT) values were tested (2.1-10.4 days). The maximum ash-free dry weight (AFDW) biomass productivity was obtained for a HRT of 3.5 days (0.29 d-1 dilution rate; 0.2 g L-1 d-1 (in terms of AFDW). The highest pollutant removal efficiencies were 92.9 and 88.5% for ammonia and total nitrogen, respectively, 40.8% for phosphorus, and 61.9% for COD. Except a dilution rate of 0.48 d-1 trial, the treated wastewater always met the Portuguese legislation quality standard for discharge into natural water bodies. Aiming to simultaneously maximize biomass volumetric productivity, CO2 biofixation rate and wastewater treatment efficiency, while minimizing residence time, 0.29 d-1 represents the optimal dilution rate value.
The potential of the produced Scenedesmus obliquus biomass was evaluated for the generation of biohydrogen through dark fermentation with Enterobacter aerogenes, and of bio-oil, bio-char and bio-gas through a pyrolysis process. The yields obtained were 67.1 mL H2 g-1 (in terms of volatile solids – VS) for bioH2 and 64, 30 and 6% for bio-oil, bio-char and bio-gas, respectively (dry mass content (%) calculated over freeze dryer biomass basis).
Title: Microalgae biomass as an alternative ingredient in cookies: Sensory, physical and chemical properties, antioxidant activity and in vitro digestibility
Authors: Ana Paula Batista, Alberto Niccolai, Patrícia Fradinho, Solange Fragoso, Ivana Bursic, Liliana Rodolfi, Natascia Biondi, Mario R. Tredici, Isabel Sousa, Anabela Raymundo
Publication: Algal Research 26 (2017) 161–171
Published: 24 July 2017
Microalgae can be regarded as an alternative and promising food ingredient due to their nutritional composition, richness in bioactive compounds, and because they are considered a sustainable protein source for the future. The aim of this work was to evaluate microalgae (Arthrospira platensis F & M-C256, Chlorella vulgaris Allma, Tetraselmis suecica F & M-M33 and Phaeodactylum tricornutum F & M-M40) as innovative ingredients to enhance functional properties of cookies. Two biomass levels were tested and compared to control: 2% (w/w) and 6% (w/w), to provide high levels of algae-bioactives. The cookies sensory and physical properties were evaluated during eight weeks showing high color and texture stability. Cookies prepared with A. platensis and C. vulgaris presented significantly (p < 0.05) higher protein content compared to the control, and by sensory analysis A. platensis cookies were preferred. Besides, A. platensis also provided a structuring effect in terms of cookies texture. All microalgae-based cookies showed significantly higher (p < 0.05) total phenolic content and in vitro antioxidant capacity compared to the control. No significant difference (p < 0.05) in in vitro digestibility between microalgae cookies and the control was found.
Title: Photodegradation and sorption govern tetracycline removal during wastewater treatment in algal ponds
Authors: Norvill Z, Toledo-Cervantes A, Blanco S, Shilton A, Guieysse B, Muñoz R
Publication: Bioresource Technology, Volume 232, Pages 35–43
Published: May 2017
The degradation of the antibiotic tetracycline, supplied at 100 µg L−1 in domestic wastewater, was studied in an outdoor, pilot scale, high rate algal pond (HRAP). Effective operation was demonstrated with the biomass concentration and the chemical oxygen demand removal efficiency averaging 1.2 ± 0.1 gTSS L−1 and 80 ± 4%, respectively, across all operational periods. Tetracycline removal exceeded 93% and 99% when the HRAP was operated at hydraulic retention times of 4 and 7 days, respectively. Batch tests and pulse testing during HRAP operation repeatedly evidenced the significance of photodegradation as a removal mechanism. Sorption dominated tetracycline removal during the night, but accounted for less than 6% of the total pollutant removal based on sorbed tetracycline extracted from biomass. Overall, these results provide the first demonstration of efficient antibiotic removal, occurring mainly via indirect photodegradation, during relevant HRAP operation (low pollutant concentration, domestic wastewater and natural sunlight).
Title: A study of photosynthetic biogas upgrading based on a high rate algal pond under alkaline conditions: Influence of the illumination regime
Authors: Franco M, Alcántara C, Noyola A, Muñoz R, Gonzalez-Sanchez A.
Publication: Science of The Total Environment, Volume 592, Pages 419–425
Published: 15 August 2017
Microalgal-bacterial processes have emerged as environmental friendly systems for the cost-effective treatment of anaerobic effluents such as biogas and nutrients-laden digestates. Environmental parameters such as temperature, irradiation, nutrient concentration and pH effect the performance of the systems. In this paper, the potential of a microalgal-bacterial photobioreactor operated under high pH (≈ 9.5) and high alkalinity to convert biogas into biomethane was evaluated. The influence of the illumination regime (continuous light supply vs 12 h/12 h light/dark cycles) on the synthetic biogas upgrading efficiency, biomass productivity and nutrient removal efficiency was assessed in a High-Rate Algal Pond interconnected to a biogas absorption bubble column. No significant differences in the removal efficiency of CO2 and H2S (91.5 ± 2% and 99.5% ± 0.5, respectively) were recorded regardless of the illumination regime. The high fluctuations of the dissolved oxygen concentration during operation under light/dark cycles allowed to evaluate the specific growth rate and the specific partial degradation rate of the microalgae biomass by photosynthesis and respiration, respectively. The respiration reduced the net microalgae biomass productivity under light/dark cycles compared with process operation under the continuous light supply.
Title: Influence of the gas-liquid flow configuration in the absorption column on photosynthetic biogas upgrading in algal-bacterial photobioreactors
Authors: Toledo-Cervantes A, Madrid-Chirinos C, Cantera S, Lebrero R, Muñoz R
Publication: Bioresource Technology, Volume 225, Pages 336–342
Published: February 2017
The potential of an algal-bacterial system consisting of a high rate algal pond (HRAP) interconnected to an absorption column (AC) via recirculation of the cultivation broth for the upgrading of biogas and digestate was investigated. The influence of the gas-liquid flow configuration in the AC on the photosynthetic biogas upgrading process was assessed. AC operation in a co-current configuration enabled to maintain a biomass productivity of 15 g m−2 d−1, while during counter-current operation biomass productivity decreased to 8.7 ± 0.5 g m−2 d−1 as a result of trace metal limitation. A bio-methane composition complying with most international regulatory limits for injection into natural gas grids was obtained regardless of the gas-liquid flow configuration. Furthermore, the influence of the recycling liquid to biogas flowrate (L/G) ratio on bio-methane quality was assessed under both operational configurations obtaining the best composition at an L/G ratio of 0.5 and co-current flow operation.
Title: Toluene biodegradation in an algal-bacterial airlift photobioreactor: Influence of the biomass concentration and of the presence of an organic phase
Authors: Lebrero R, Angeles R, Perez R, Muñoz R
Publication: Journal of Environmental Management, Volume 183, Part 3, Pages 585–593
Published: 1 December 2016
The potential of algal-bacterial symbiosis for off-gas abatement was investigated for the first time by comparatively evaluating the performance of a bacterial (CB) and an algal-bacterial (PB) airlift bioreactors during the treatment of a 6 g m−3 toluene laden air emission. The influence of biomass concentration and of the addition of a non-aqueous phase was also investigated. A poor and fluctuating performance was recorded during the initial stages of the experiment, which was attributed to the low biomass concentration present in both reactors and to the accumulation of toxic metabolites. In this sense, an increase in the dilution rate from 0.23 to 0.45 d−1 and in biomass concentration from ∼1 to ∼5 g L−1 resulted in elimination capacities (ECs) of 300 g m−3h−1 (corresponding to removal efficiencies ∼ 90%). Microalgae activity allowed for a reduction in the emitted CO2 and an increase in dissolved O2 concentration in the PB. However, excess biomass growth over 11 g L−1 hindered light penetration and severely decreased photosynthetic activity. The addition of silicone oil at 20% (on a volume basis) stabilized system performance, leading to dissolved O2 concentrations of 7 mg L−1 and steady ECs of 320 g m−3 h−1 in the PB. The ECs here recorded were considerably higher than those previously reported in toluene-degrading bioreactors. Finally, microbial population analysis by DGGE-sequencing demonstrated the differential specialization of the microbial community in both reactors, likely resulting in different toluene degradation pathways and metabolites production.
Title: Influence of different degrees of N limitation on photosystem II performance and heterogeneity of Chlorella vulgaris
Authors: Giorgos Markou, Ly HT Dao, Koenraad Muylaert, and John Beardall
Publication: Algal Research, Volume 26, September 2017, Pages 84-92
Published: 12 July 2017
Nitrogen (N) limitation is considered as the most efficient strategy to induce the accumulation of lipids, carbohydrates or other target compounds in microalgal biomass. However, along with biomass biochemical composition, alterations in N limitation affect the photosynthetic apparatus and result in decreased growth. In this study, Chlorella vulgaris was cultivated in semi-continuous mode with different degrees of N limitation and chlorophyll (Chl) fluorescence analyses were used to investigate the effect of N limitation on photosystem II (PSII) performance, in terms of structural and functional heterogeneity. As expected, N limitation resulted in the decrease of quantum yield and calculated OJIP parameters related to PSII performance. N limitation resulted in a significant increase of trapped energy per reaction center (RC) and subsequently to higher dissipation of excess energy. However, despite the negative effect of N limitation on the number of RCs, the electron transport beyond QA as well the capacity of reducing/re-oxidation of plastiquinone were not negatively affected, implying that performance of RCs was not affected by N limitation. Photochemical quenching (qp) increased of as N limitation increased while the curve of non-photochemical quenching (NPQ) was unimodal, i.e. increased up to a level of N limitation and then decreased as N limitation degree increased further. The overall results of the present study suggest that the decrease of PSII performance was due to a reduction of the number of RCs accompanied with higher energy dissipation a probable outcome of the decreased need for reductant by cells due to lower metabolic activity under N limitation.
Title: Saccharification of microalgae biomass obtained from wastewater treatment by enzymatic hydrolysis. Effect of alkaline-peroxide pretreatment
Authors: Martin-Juárez J, Lorenzo-Hernando A, Muñoz-Torre R, Blanco-Lanza S, Bolado-Rodríguez S
Publication: Bioresource Technology, Volume 218, Pages 265–271
Published: October 2016
An enzymatic method for the carbohydrate hydrolysis of different microalgae biomass cultivated in domestic (DWB) and pig manure (PMWB) wastewaters, at different storage conditions (fresh, freeze-dried and reconstituted), was evaluated. The DWB provided sugars yields between 40 and 63%, although low xylose yields (< 23.5%). Approximately 2% of this biomass was converted to byproducts as succinic, acetic and formic acids. For PMWB, a high fraction of the sugars (up to 87%) was extracted, but mainly converted into acetic, butyric and formic acids, which was attributed to the bacterial action. In addition, the performance of an alkaline-peroxide pretreatment, conducted for 1 h, 50 °C and H2O2 concentrations from 1 to 7.5% (w/w), was essayed. The hydrolysis of pretreated microalgae supported a wide range of sugars extraction for DWB (55–90%), and 100% for PMWB. Nevertheless, a large fraction of these sugars (∼30% for DWB and 100% for PMWB) was transformed to byproducts.
Title: Effect of light intensity on the degree of ammonia toxicity on PSII activity of Arthrospira platensis and Chlorella vulgaris
Authors: Giorgos Markou, and Koenraad Muylaert
Publication: Bioresource Technology, Volume 216, September 2016, Pages 453-461
Published: 25 May 2016
Herein the effect of increasing light intensity on the degree of ammonia toxicity and its impact on the photosynthetic performance of Arthrospira and Chlorella was investigated using Chl fluorescence as a technique to characterize their photosystem II (PSII) activity. The results revealed that the increase of light intensity amplifies the ammonia toxicity on PSII. Chl fluorescence transients shown that at a given free ammonia (FA) concentration (100 mg-N/L), the photochemistry potential decreased by increasing light intensity. The inhibition of the PSII was not reversible either by re-incubating the cells under dark or under decreased FA concentration. Moreover, the decrease of photochemical and non-photochemical quenching (NPQ) of fluorescence suggest that ammonia toxicity decreases the open available PSII centers, as well the inability of PSII to transfer the generated electrons beyond QA. The collapse of NPQ suggests that ammonia toxicity inhibits the photoprotection mechanism(s) and hence renders PSII more sensitive to photoinhibition.
Title: The Diatom Staurosirella pinnata for Photoactive Material Production
Authors: Roberta De Angelis, Sonia Melino, Paolo Prosposito, Mauro Casalboni, Francesca Romana Lamastra, Francesca Nanni, Laura Bruno, Roberta Congestri
Publication: PLoS ONE 11(11): e0165571
Published: November 9, 2016
A native isolate of the colonial benthic diatom Staurosirella pinnata was cultivated for biosilica production. The silicified cell walls (frustules) were used as a source of homogeneous and structurally predictable porous biosilica for dye trapping and random laser applications. This was coupled with the extraction of lipids from biomass showing potential to fabricate photoactive composite materials sustainably. The strain was selected for its ease of growth in culture and harvesting. Biosilica and lipids were obtained at the end of growth in indoor photobioreactors. Frustules were structurally characterized microscopically and their chemistry analyzed with Fourier Transform Infrared Spectroscopy. Frustule capacity of binding laser dyes was evaluated on a set of frustules/Rhodamine B (Rho B) solutions and with respect to silicon dioxide and diatomite by Fluorescence Spectroscopy demonstrating a high affinity for the organic dye. The effect of dye trapping property in conveying Rho B emission to frustules, with enhancement of scattering events, was analyzed on Rho B doped polyacrylamide gels filled or not with frustules. Amplified spontaneous emission was recorded at increasing pump power indicating the onset of a random laser effect in frustule filled gels at lower power threshold compared to unfilled matrices.
Title: Microalga Nannochloropsis sp. biomass for biodiesel production: conventional (cell disruption) and in situ transesterification
Authors: Gouveia, L.; Janelas, J.; Torpecelo, A.; Oliveira, A.C.
Publication: Journal of Marine Biology & Oceanography
Published: April 19, 2016
The potential of Nannochloropsis sp. microalga to biodiesel production was assessed. The work deals with the optimization of the cell disruption, a required step when the lipid extraction followed by the transesterification reaction is the option to produce biodiesel, as well as the optimization of the reaction parameters (catalyst, alcohol, temperature and time) of the in situ transesterification (direct conversion of the saponifiable lipids into FAME – fatty acid metyl esters, usually called as biodiesel, in one step). The cell rupture of wet and dried biomass (by oven and freezedryer) using different methods (physical – coffee grinder and ball-mill; and thermodynamic – microwaves and autoclave) was evaluated. The highest lipid recovery (42.4 ± 0.2% g of lipids /g of oven dried biomass) was attained from the oven dried biomass pretreated in a coffee grinder followed by a ball milling. The microalgal oil quality (fatty acid profile, acid value and iodine value) was determined and was not influenced by the biomass state (oven or freeze-dried) nor by the cell rupture method, being mainly composed of palmitic (C16:0), palmitoleic (C16:1) and oleic (C18:1) acids. The linoleic acid (C18:3) content is quite low (< 0.35% w/w) which results in a high quality biodiesel in terms of this parameter. The viability of the in situ transesterification, in order to reduce technological challenges, energy, time, environmental negative impacts and costs of the traditional processes, was studied and optimized The most favourable conditions were found to be 3.16 g of methanol / 100 g of dry biomass, 1.2% v/v of catalyst (H2SO4), for 6 h at 50°C, which allows of 95% esters formation. In terms of the cell rupture, the coffee grinder followed by the ball mill, proved again, to be the most efficient process, promoting an increase in the transesterification reaction rate.
Title: Microalgae biomass production using wastewater: treatment and costs. Scaleup considerations
Authors: Gouveia, L.; G raça, S.; Sousa, C.; Ambrosano, L; Ribeiro, B.; Botrel E.P.; Neto, P.C.; Ferreira, Ana F.; Silva, CM.
Publication: Algal Research 16, 167–176
Published: June 2016
This work is part of a LIFE project to treat urban wastewater from Águas da Figueira (AdF, Figueira da Foz, PT) using a vertical tubular photobioreactor (PBR) prototype (150 L), to be scaled up and integrated in a waste water treatment plant (WWTP). The PBR was inoculated with three different microalgae: Chlorella vulgaris (Cv), Scenedesmus obliquus (Sc) and Consortium C (ConsC), isolated from the effluent. The study intends to find the best microalga in terms of wastewater remediation, biomass productivity and quality, for further uses, such as biofuel, biofertilizer and bioplastic production.
Title: Capturing biodiversity: linking a cyanobacteria culture collection to the “scratchpads” virtual research environment enhances biodiversity knowledge
Authors: Spyros Gkelis, Manthos Panou
Publication: Biodiversity Data Journal 4: e7965
Published: 06 Apr 2016 (Open-Access)
Currently, cyanobacterial diversity is examined using a polyphasic approach by assessing morphological and molecular data (Komárek 2015). However, the comparison of morphological and genetic data is sometimes hindered by the lack of cultures of several cyanobacterial morphospecies and inadequate morphological data of sequenced strains (Rajaniemi et al. 2005). Furthermore, in order to evaluate the phenotypic plasticity within defined taxa, the variability observed in cultures has to be compared to the range in natural variation (Komárek and Mareš 2012). Thus, new tools are needed to aggregate, link and process data in a meaningful way, in order to properly study and understand cyanodiversity.
An online database on cyanobacteria has been created, namely the Cyanobacteria culture collection (CCC) (http://cyanobacteria.myspecies.info/) using as case studies cyanobacterial strains isolated from lakes of Greece, which are part of the AUTH culture collection (School of Biology, Aristotle University of Thessaloniki). The database hosts, for the first time, information and data such as morphology/morphometry, biogeography, phylogeny, microphotographs, distribution maps, toxicology and biochemical traits of the strains. All this data are structured managed, and presented online and are publicly accessible with a recently developed tool, namely “Scratchpads”, a taxon-centric virtual research environment allowing browsing the taxonomic classification and retrieving various kinds of relevant information for each taxon.
cyanobacteria, database, Scratchpads, taxonomy, morphology, phylogeny, biodiversity informatics
Title: EUALGAE: Microalgae proteins and ingredients
Author: Maria Hayes, Teagasc Food Research Centre, Ashtown
Publication: TResearch, Volume 11: Number 1. Spring 2016, 32‐33.
Authors: Cristina Gonzalez-Fernandez, Bruno Sialve, Beatriz Molinuevo-Salces
Publication: Bioresource Technology, 2015, 198, 896‐906.
• Microalgae biomass has a huge potential as feedstock for biogas production.
• Novel pretreatments, reactor designs and operation parameters are addressed.
• The microbial community carrying out anaerobic digestion is reviewed.
• Research on intermediate compounds exploitation is discussed.
• Integration of microalgae culture and anaerobic digestion is outlined.