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Koenraad Muylaert - One of the best experts on this subject based on the ideXlab platform.
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optimization of negatively charged polysulfone membranes for concentration and purification of extracellular polysaccharides from Arthrospira platensis using the response surface methodology
Separation and Purification Technology, 2020Co-Authors: Zhenyu Zhao, Koenraad Muylaert, Sara Paulina Cuellar Bermudez, Ayesha Ilyas, Ivo F J VankelecomAbstract:Abstract Arthrospira platensis (A. platensis), one of the successfully commercialized microalgae, can generate abundant extracellular polysaccharides (EPS). Separating the EPS from the culture medium is important to recycle the medium and further process the polysaccharide resource. To separate EPS from spent Arthrospira platensis culture medium, a negatively charged polysulfone (PSf) membrane was prepared by lending PSf with sulfonated PSf (sPSf), and was optimized using the response surface methodology. The optimal preparation conditions were found to be a PSf concentration of 12.5 w%, sPSf of 1.9 w% and PEG of 5.5 w% in N,N-dimetylacetamide. The hydrophilicity, porosity, mean pore size, infrared absorption spectrum, water uptake (WU), thickness and clean water permeability (CWP) were determined to characterize the membrane, and critical pressure was used to evaluate the fouling resistance of the membrane. The results show that sPSf was successfully incorporated in the optimized PSf/sPSf, and it had higher hydrophilicity, porosity, larger mean pore size, WU, CWP, thickness and higher EPS retention and lower protein retention than the pristine PSf membrane. The final EPS retention of the optimized membrane was higher than 96%.
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Harvesting of Arthrospira platensis with helicoidal and straight trichomes using filtration and centrifugation
Separation Science and Technology, 2019Co-Authors: Sara P. Cuellar-bermudez, Ruddy Wattiez, Evmorfia Kilimtzidi, Jolien Devaere, Koen Goiris, Cristina González-fernández, Koenraad MuylaertAbstract:is the most widely cultivated strain of all microalgae and cyanobacteria. Arthrospira forms helical trichomes that, under certain circumstances, can switch to a straight morphology. This study comp...
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trade off between growth and carbohydrate accumulation in nutrient limited Arthrospira sp pcc 8005 studied by integrating transcriptomic and proteomic approaches
PLOS ONE, 2015Co-Authors: Orily Depraetere, Imogen Foubert, Frédéric Deschoenmaeker, Hanène Badri, Natalie Leys, Ruddy Wattiez, Pieter Monsieurs, Koenraad MuylaertAbstract:Cyanobacteria have a strong potential for biofuel production due to their ability to accumulate large amounts of carbohydrates. Nitrogen (N) stress can be used to increase the content of carbohydrates in the biomass, but it is expected to reduce biomass productivity. To study this trade-off between carbohydrate accumulation and biomass productivity, we characterized the biomass productivity, biomass composition as well as the transcriptome and proteome of the cyanobacterium Arthrospira sp. PCC 8005 cultured under N-limiting and N-replete conditions. N limitation resulted in a large increase in the carbohydrate content of the biomass (from 14 to 74%) and a decrease in the protein content (from 37 to 10%). Analyses of fatty acids indicated that no lipids were accumulated under N-limited conditions. Nevertheless, it did not affect the biomass productivity of the culture up to five days after N was depleted from the culture medium. Transcriptomic and proteomic analysis indicated that de novo protein synthesis was down-regulated in the N-limited culture. Proteins were degraded and partly converted into carbohydrates through gluconeogenesis. Cellular N derived from protein degradation was recycled through the TCA and GS-GOGAT cycles. In addition, photosynthetic energy production and carbon fixation were both down-regulated, while glycogen synthesis was up-regulated. Our results suggested that N limitation resulted in a redirection of photosynthetic energy from protein synthesis to glycogen synthesis. The fact that glycogen synthesis has a lower energy demand than protein synthesis might explain why Arthrospira is able to achieve a similar biomass productivity under N-limited as under N-replete conditions despite the fact that photosynthetic energy production was impaired by N limitation.
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Influence of culture medium recycling on the performance of Arthrospira platensis cultures
Algal Research - Biomass Biofuels and Bioproducts, 2015Co-Authors: Orily Depraetere, Imogen Foubert, Guillaume Pierre, Philippe Michaud, Wim Noppe, Dries Vandamme, Koenraad MuylaertAbstract:To reduce the water footprint of microalgae biomass production, it is essential to recycle the culture medium. The influence of medium recycling on the performance of the cyanobacterium Arthrospira platensis, the most widely cultivated microalgae, was investigated. Arthrospira was harvested with a 20 μm mesh size microstrainer, which is the benchmark harvesting technology for Arthrospira production. Repeated recycling of the culture medium resulted in a decline in growth rate and the maximum quantum yield of photosynthesis (Fv/Fm) when compared to a control culture in fresh medium. This decline was accompanied by accumulation of organic matter in the culture medium (up to 104 mg C L− 1). This organic matter consists of 70% of sugars, mostly rhamnose-rich polysaccharides with uronic acids. Accumulation of polysaccharides resulted in a decrease in the filtration rate through the microstrainer used for harvesting. Part of the biomass escaped harvesting and was returned to the culture with the recycled medium. This resulted in a change in the Arthrospira population and reduction in the harvesting efficiency, but this change in population had no effect on the growth rate. The growth rate of Arthrospira in the recycled culture medium was primarily influenced by organic matter that accumulated in the medium.
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Harvesting carbohydrate-rich Arthrospira platensis by spontaneous settling
Bioresource Technology, 2015Co-Authors: Orily Depraetere, Giorgos Markou, Imogen Foubert, Guillaume Pierre, Frédéric Deschoenmaeker, Hanène Badri, Natalie Leys, Ruddy Wattiez, Philippe Michaud, Koenraad MuylaertAbstract:The filamentous cyanobacterium Arthrospira platensis is an attractive feedstock for carbohydrate-based biofuels because it accumulated up to 74% of carbohydrates when nitrogen stressed. Nitrogen stressed A. platensis also settled spontaneously, and this occurred simultaneously with carbohydrates accumulation, suggesting a link between both phenomena. The increased settling velocity was neither due to production of extracellular carbohydrates, nor due to degradation of gas vacuoles, but was caused by an increase in the specific density of the filaments as a result of accumulation of carbohydrates under the form of glycogen. Settling velocities of carbohydrate-rich A. platensis reached 0.64 m h−1, which allowed the biomass to be harvested using a lamella separator. The biomass could be concentrated at least 15 times, allowing removal of 94% of the water using gravity settling, thus offering a potential application as a low-cost and high-throughput method for primary dewatering of carbohydrate-rich A. platensis.
Ruddy Wattiez - One of the best experts on this subject based on the ideXlab platform.
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Harvesting of Arthrospira platensis with helicoidal and straight trichomes using filtration and centrifugation
Separation Science and Technology, 2019Co-Authors: Sara P. Cuellar-bermudez, Ruddy Wattiez, Evmorfia Kilimtzidi, Jolien Devaere, Koen Goiris, Cristina González-fernández, Koenraad MuylaertAbstract:is the most widely cultivated strain of all microalgae and cyanobacteria. Arthrospira forms helical trichomes that, under certain circumstances, can switch to a straight morphology. This study comp...
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trade off between growth and carbohydrate accumulation in nutrient limited Arthrospira sp pcc 8005 studied by integrating transcriptomic and proteomic approaches
PLOS ONE, 2015Co-Authors: Orily Depraetere, Imogen Foubert, Frédéric Deschoenmaeker, Hanène Badri, Natalie Leys, Ruddy Wattiez, Pieter Monsieurs, Koenraad MuylaertAbstract:Cyanobacteria have a strong potential for biofuel production due to their ability to accumulate large amounts of carbohydrates. Nitrogen (N) stress can be used to increase the content of carbohydrates in the biomass, but it is expected to reduce biomass productivity. To study this trade-off between carbohydrate accumulation and biomass productivity, we characterized the biomass productivity, biomass composition as well as the transcriptome and proteome of the cyanobacterium Arthrospira sp. PCC 8005 cultured under N-limiting and N-replete conditions. N limitation resulted in a large increase in the carbohydrate content of the biomass (from 14 to 74%) and a decrease in the protein content (from 37 to 10%). Analyses of fatty acids indicated that no lipids were accumulated under N-limited conditions. Nevertheless, it did not affect the biomass productivity of the culture up to five days after N was depleted from the culture medium. Transcriptomic and proteomic analysis indicated that de novo protein synthesis was down-regulated in the N-limited culture. Proteins were degraded and partly converted into carbohydrates through gluconeogenesis. Cellular N derived from protein degradation was recycled through the TCA and GS-GOGAT cycles. In addition, photosynthetic energy production and carbon fixation were both down-regulated, while glycogen synthesis was up-regulated. Our results suggested that N limitation resulted in a redirection of photosynthetic energy from protein synthesis to glycogen synthesis. The fact that glycogen synthesis has a lower energy demand than protein synthesis might explain why Arthrospira is able to achieve a similar biomass productivity under N-limited as under N-replete conditions despite the fact that photosynthetic energy production was impaired by N limitation.
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Harvesting carbohydrate-rich Arthrospira platensis by spontaneous settling
Bioresource Technology, 2015Co-Authors: Orily Depraetere, Giorgos Markou, Imogen Foubert, Guillaume Pierre, Frédéric Deschoenmaeker, Hanène Badri, Natalie Leys, Ruddy Wattiez, Philippe Michaud, Koenraad MuylaertAbstract:The filamentous cyanobacterium Arthrospira platensis is an attractive feedstock for carbohydrate-based biofuels because it accumulated up to 74% of carbohydrates when nitrogen stressed. Nitrogen stressed A. platensis also settled spontaneously, and this occurred simultaneously with carbohydrates accumulation, suggesting a link between both phenomena. The increased settling velocity was neither due to production of extracellular carbohydrates, nor due to degradation of gas vacuoles, but was caused by an increase in the specific density of the filaments as a result of accumulation of carbohydrates under the form of glycogen. Settling velocities of carbohydrate-rich A. platensis reached 0.64 m h−1, which allowed the biomass to be harvested using a lamella separator. The biomass could be concentrated at least 15 times, allowing removal of 94% of the water using gravity settling, thus offering a potential application as a low-cost and high-throughput method for primary dewatering of carbohydrate-rich A. platensis.
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proteome wide analysis and diel proteomic profiling of the cyanobacterium Arthrospira platensis pcc 8005
PLOS ONE, 2014Co-Authors: Sabine Matallanasurget, Frédéric Deschoenmaeker, Hanène Badri, Baptiste Leroy, Jeremy Derock, Ruddy WattiezAbstract:The filamentous cyanobacterium Arthrospira platensis has a long history of use as a food supply and it has been used by the European Space Agency in the MELiSSA project, an artificial microecosystem which supports life during long-term manned space missions. This study assesses progress in the field of cyanobacterial shotgun proteomics and light/dark diurnal cycles by focusing on Arthrospira platensis. Several fractionation workflows including gel-free and gel-based protein/peptide fractionation procedures were used and combined with LC-MS/MS analysis, enabling the overall identification of 1306 proteins, which represents 21% coverage of the theoretical proteome. A total of 30 proteins were found to be significantly differentially regulated under light/dark growth transition. Interestingly, most of the proteins showing differential abundance were related to photosynthesis, the Calvin cycle and translation processes. A novel aspect and major achievement of this work is the successful improvement of the cyanobacterial proteome coverage using a 3D LC-MS/MS approach, based on an immobilized metal affinity chromatography, a suitable tool that enabled us to eliminate the most abundant protein, the allophycocyanin. We also demonstrated that cell growth follows a light/dark cycle in A. platensis. This preliminary proteomic study has highlighted new characteristics of the Arthrospira platensis proteome in terms of diurnal regulation.
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Genome Sequence of the Edible Cyanobacterium Arthrospira sp. PCC 8005
Journal of bacteriology, 2010Co-Authors: Paul Janssen, Ruddy Wattiez, Annick Wilmotte, Baptiste Leroy, Nicolas Morin, Tatiana Vallaeys, Malgorzata Waleron, Krzysztof Waleron, Max Mergeay, Philippe QuillardetAbstract:We determined the genome sequence of Arthrospira sp. PCC 8005, a cyanobacterial strain of great interest to the European Space Agency for its nutritive value and oxygenic properties in the Micro-Ecological Life Support System Alternative (MELiSSA) biological life support system for long-term manned missions into space.
Orily Depraetere - One of the best experts on this subject based on the ideXlab platform.
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trade off between growth and carbohydrate accumulation in nutrient limited Arthrospira sp pcc 8005 studied by integrating transcriptomic and proteomic approaches
PLOS ONE, 2015Co-Authors: Orily Depraetere, Imogen Foubert, Frédéric Deschoenmaeker, Hanène Badri, Natalie Leys, Ruddy Wattiez, Pieter Monsieurs, Koenraad MuylaertAbstract:Cyanobacteria have a strong potential for biofuel production due to their ability to accumulate large amounts of carbohydrates. Nitrogen (N) stress can be used to increase the content of carbohydrates in the biomass, but it is expected to reduce biomass productivity. To study this trade-off between carbohydrate accumulation and biomass productivity, we characterized the biomass productivity, biomass composition as well as the transcriptome and proteome of the cyanobacterium Arthrospira sp. PCC 8005 cultured under N-limiting and N-replete conditions. N limitation resulted in a large increase in the carbohydrate content of the biomass (from 14 to 74%) and a decrease in the protein content (from 37 to 10%). Analyses of fatty acids indicated that no lipids were accumulated under N-limited conditions. Nevertheless, it did not affect the biomass productivity of the culture up to five days after N was depleted from the culture medium. Transcriptomic and proteomic analysis indicated that de novo protein synthesis was down-regulated in the N-limited culture. Proteins were degraded and partly converted into carbohydrates through gluconeogenesis. Cellular N derived from protein degradation was recycled through the TCA and GS-GOGAT cycles. In addition, photosynthetic energy production and carbon fixation were both down-regulated, while glycogen synthesis was up-regulated. Our results suggested that N limitation resulted in a redirection of photosynthetic energy from protein synthesis to glycogen synthesis. The fact that glycogen synthesis has a lower energy demand than protein synthesis might explain why Arthrospira is able to achieve a similar biomass productivity under N-limited as under N-replete conditions despite the fact that photosynthetic energy production was impaired by N limitation.
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Influence of culture medium recycling on the performance of Arthrospira platensis cultures
Algal Research - Biomass Biofuels and Bioproducts, 2015Co-Authors: Orily Depraetere, Imogen Foubert, Guillaume Pierre, Philippe Michaud, Wim Noppe, Dries Vandamme, Koenraad MuylaertAbstract:To reduce the water footprint of microalgae biomass production, it is essential to recycle the culture medium. The influence of medium recycling on the performance of the cyanobacterium Arthrospira platensis, the most widely cultivated microalgae, was investigated. Arthrospira was harvested with a 20 μm mesh size microstrainer, which is the benchmark harvesting technology for Arthrospira production. Repeated recycling of the culture medium resulted in a decline in growth rate and the maximum quantum yield of photosynthesis (Fv/Fm) when compared to a control culture in fresh medium. This decline was accompanied by accumulation of organic matter in the culture medium (up to 104 mg C L− 1). This organic matter consists of 70% of sugars, mostly rhamnose-rich polysaccharides with uronic acids. Accumulation of polysaccharides resulted in a decrease in the filtration rate through the microstrainer used for harvesting. Part of the biomass escaped harvesting and was returned to the culture with the recycled medium. This resulted in a change in the Arthrospira population and reduction in the harvesting efficiency, but this change in population had no effect on the growth rate. The growth rate of Arthrospira in the recycled culture medium was primarily influenced by organic matter that accumulated in the medium.
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Harvesting carbohydrate-rich Arthrospira platensis by spontaneous settling
Bioresource Technology, 2015Co-Authors: Orily Depraetere, Giorgos Markou, Imogen Foubert, Guillaume Pierre, Frédéric Deschoenmaeker, Hanène Badri, Natalie Leys, Ruddy Wattiez, Philippe Michaud, Koenraad MuylaertAbstract:The filamentous cyanobacterium Arthrospira platensis is an attractive feedstock for carbohydrate-based biofuels because it accumulated up to 74% of carbohydrates when nitrogen stressed. Nitrogen stressed A. platensis also settled spontaneously, and this occurred simultaneously with carbohydrates accumulation, suggesting a link between both phenomena. The increased settling velocity was neither due to production of extracellular carbohydrates, nor due to degradation of gas vacuoles, but was caused by an increase in the specific density of the filaments as a result of accumulation of carbohydrates under the form of glycogen. Settling velocities of carbohydrate-rich A. platensis reached 0.64 m h−1, which allowed the biomass to be harvested using a lamella separator. The biomass could be concentrated at least 15 times, allowing removal of 94% of the water using gravity settling, thus offering a potential application as a low-cost and high-throughput method for primary dewatering of carbohydrate-rich A. platensis.
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decolorisation of piggery wastewater to stimulate the production of Arthrospira platensis
Bioresource Technology, 2013Co-Authors: Orily Depraetere, Imogen Foubert, Koenraad MuylaertAbstract:The aim of this study was to evaluate the potential of color removal methods for enhancing the growth rate and biomass yield of Arthrospira produced using piggery wastewater as a nutrient source. Color could be removed from the piggery wastewater by means of oxidation (H2O2–UV) or by means of positively charged flocculants (e.g., ferric chloride, magnesium hydroxide), biopolymers (chitosan, cationic starch) or adsorbents (hydrotalcite). Some methods remove not only color but also phosphate (e.g., hydrotalcite) while other do not affect phosphate concentrations (e.g., chitosan). Color removal using chitosan resulted in a doubling of initial growth rate and a 50% increase in final biomass yield of Arthrospira produced on piggery wastewater. Color removal using hydrotalcite resulted in a low biomass yield of Arthrospira due to phosphate limitation.
Moheimani N.r. - One of the best experts on this subject based on the ideXlab platform.
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Outdoor phycocyanin production in a standalone thermally-insulated photobioreactor
'Elsevier BV', 2020Co-Authors: Nwoba E.g., Laird D.w., Alameh K., Parlevliet D.a., Moheimani N.r.Abstract:The operation of solar microalgal photobioreactors requires sufficient cooling and heating to maintain reliable high productivity year-round. These operations are energy-intensive and expensive. Growth characteristics and phycocyanin production of Arthrospira platensis were investigated during the austral winter using a thermally-insulated photobioreactor with photovoltaic panel integration for electricity generation. This was compared with a control photobioreactor under a cycle of heating (13-hour night) and thermostat-regulated cooling, and continuously heated raceway pond. Average temperature in the photovoltaic photobioreactor (21.0 ± 0.03 °C) was similar to that in the heated control. Biomass productivity of Arthrospira in the novel photobioreactor was 67% higher than in the raceway pond but significantly lower than the control. Phycocyanin productivity (16.3 ± 1.43 mgg−1d−1 and purity (1.2 ± 0.03) showed no variation between photobioreactors but was significantly lower in the raceway pond. Electrical energy output of the photovoltaic photobioreactor exceeded mixing energy needs by 75%. These results indicate that the novel photobioreactor offers a reliable, energy-efficient platform for large-scale production of high-value chemicals from microalgae
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Effect of organic carbon source and nutrient depletion on the simultaneous production of a high value bioplastic and a specialty pigment by Arthrospira platensis
'Elsevier BV', 2020Co-Authors: Laird D.w., Hughes L.j., Raeisossadati M., Moheimani N.r.Abstract:Many studies have shown enhanced production of single high value products from microalgal cultivation can be achieved by employing nutrient limitation and/or organic carbon supplementation. The possibility of exploiting multiple high value microalgal biosynthetic products has rarely been examined, even though it is widely acknowledged that such systems are likely to improve the economics of chemical production from this source. The co-production of two high value microalgal products, phycocyanin and polyhydroxybutyrate (PHB), was investigated under photoautotrophic and mixotrophic conditions, with and without nutrient limitation, in Arthrospira (Spirulina) platensis MUR126 cultures. Cultures accumulated PHB under nutrient replete phototrophic conditions while maintaining phycocyanin levels. Supplementing Arthrospira platensis cultures with additional CO2 increased PHB (33% at day 14), biomass (23 %) and phycocyanin productivity (30%). The results from cultures grown mixotrophically using organic carbon sources commonly found in agricultural and industrial waste streams (acetate, formate, glycerol and oxalate), and under nutrient limitation, did not show a definitive trend. When Arthrospira platensis was cultured in media devoid of both N and P, supplementing with glycerol and acetate led to a significant increase in biomass productivity compared to a photoautotrophic reference culture, but negatively affected both phycocyanin and PHB production. The poor co-production results for Arthrospira platensis under mixotrophic conditions suggest that a minimum level of N is required to maintain phycocyanin levels and a greater concentration of the organic C source is needed to create a redox balance within the cells that enhances PHB production
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Sustainable phycocyanin production from Arthrospira platensis using solar-control thin film coated photobioreactor
'Elsevier BV', 2019Co-Authors: Nwoba E.g., Laird D.w., Alameh K., Parlevliet D.a., Moheimani N.r.Abstract:Solar irradiance consists of photosynthetically-active visible photons that can be transformed to valuable biomolecules by microalgae. Light also has undesirable non-photosynthetic photons, such as ultraviolet and infrared wavelengths that heat up algal closed photobioreactors above optimum temperatures for growth. In this study, a solar control infrared blocking film (IRF) is applied to an algal flat plate photobioreactor to block excessive non-photosynthetic photons and regulate the temperature profile of Arthrospira platensis cultures for the production of C-phycocyanin (C-PC). The performance of the IRF is compared against other cooling mechanisms such as insulated-glazed photovoltaic (IGP), conventional water-jacket (CWJ) and a no heat control (NHC) photobioreactors. Experimental results show that the maximum temperature (30.94 ± 0.09 °C) in the IRF culture is only 5% higher than that in CWJ culture but 33% lower than that in NHC cultures. No significant differences were found in C-PC content or biomass productivity when Arthrospira is grown using IGP, CWJ or IRF but is significantly lower in NHC photobioreactors. Chlorophyll a fluorescence probing of A. platensis shows that IRF, IGP and CWJ cultures are not thermally stressed, however, NHCs cultures are highly stressed due to supraoptimal temperatures. Our results clearly indicate that solar control film is a potential tool for blocking non-photosynthetic photons and managing culture temperature in flat plate photobioreactors for sustainable C-phycocyanin production from A. platensis
Imogen Foubert - One of the best experts on this subject based on the ideXlab platform.
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trade off between growth and carbohydrate accumulation in nutrient limited Arthrospira sp pcc 8005 studied by integrating transcriptomic and proteomic approaches
PLOS ONE, 2015Co-Authors: Orily Depraetere, Imogen Foubert, Frédéric Deschoenmaeker, Hanène Badri, Natalie Leys, Ruddy Wattiez, Pieter Monsieurs, Koenraad MuylaertAbstract:Cyanobacteria have a strong potential for biofuel production due to their ability to accumulate large amounts of carbohydrates. Nitrogen (N) stress can be used to increase the content of carbohydrates in the biomass, but it is expected to reduce biomass productivity. To study this trade-off between carbohydrate accumulation and biomass productivity, we characterized the biomass productivity, biomass composition as well as the transcriptome and proteome of the cyanobacterium Arthrospira sp. PCC 8005 cultured under N-limiting and N-replete conditions. N limitation resulted in a large increase in the carbohydrate content of the biomass (from 14 to 74%) and a decrease in the protein content (from 37 to 10%). Analyses of fatty acids indicated that no lipids were accumulated under N-limited conditions. Nevertheless, it did not affect the biomass productivity of the culture up to five days after N was depleted from the culture medium. Transcriptomic and proteomic analysis indicated that de novo protein synthesis was down-regulated in the N-limited culture. Proteins were degraded and partly converted into carbohydrates through gluconeogenesis. Cellular N derived from protein degradation was recycled through the TCA and GS-GOGAT cycles. In addition, photosynthetic energy production and carbon fixation were both down-regulated, while glycogen synthesis was up-regulated. Our results suggested that N limitation resulted in a redirection of photosynthetic energy from protein synthesis to glycogen synthesis. The fact that glycogen synthesis has a lower energy demand than protein synthesis might explain why Arthrospira is able to achieve a similar biomass productivity under N-limited as under N-replete conditions despite the fact that photosynthetic energy production was impaired by N limitation.
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Influence of culture medium recycling on the performance of Arthrospira platensis cultures
Algal Research - Biomass Biofuels and Bioproducts, 2015Co-Authors: Orily Depraetere, Imogen Foubert, Guillaume Pierre, Philippe Michaud, Wim Noppe, Dries Vandamme, Koenraad MuylaertAbstract:To reduce the water footprint of microalgae biomass production, it is essential to recycle the culture medium. The influence of medium recycling on the performance of the cyanobacterium Arthrospira platensis, the most widely cultivated microalgae, was investigated. Arthrospira was harvested with a 20 μm mesh size microstrainer, which is the benchmark harvesting technology for Arthrospira production. Repeated recycling of the culture medium resulted in a decline in growth rate and the maximum quantum yield of photosynthesis (Fv/Fm) when compared to a control culture in fresh medium. This decline was accompanied by accumulation of organic matter in the culture medium (up to 104 mg C L− 1). This organic matter consists of 70% of sugars, mostly rhamnose-rich polysaccharides with uronic acids. Accumulation of polysaccharides resulted in a decrease in the filtration rate through the microstrainer used for harvesting. Part of the biomass escaped harvesting and was returned to the culture with the recycled medium. This resulted in a change in the Arthrospira population and reduction in the harvesting efficiency, but this change in population had no effect on the growth rate. The growth rate of Arthrospira in the recycled culture medium was primarily influenced by organic matter that accumulated in the medium.
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Harvesting carbohydrate-rich Arthrospira platensis by spontaneous settling
Bioresource Technology, 2015Co-Authors: Orily Depraetere, Giorgos Markou, Imogen Foubert, Guillaume Pierre, Frédéric Deschoenmaeker, Hanène Badri, Natalie Leys, Ruddy Wattiez, Philippe Michaud, Koenraad MuylaertAbstract:The filamentous cyanobacterium Arthrospira platensis is an attractive feedstock for carbohydrate-based biofuels because it accumulated up to 74% of carbohydrates when nitrogen stressed. Nitrogen stressed A. platensis also settled spontaneously, and this occurred simultaneously with carbohydrates accumulation, suggesting a link between both phenomena. The increased settling velocity was neither due to production of extracellular carbohydrates, nor due to degradation of gas vacuoles, but was caused by an increase in the specific density of the filaments as a result of accumulation of carbohydrates under the form of glycogen. Settling velocities of carbohydrate-rich A. platensis reached 0.64 m h−1, which allowed the biomass to be harvested using a lamella separator. The biomass could be concentrated at least 15 times, allowing removal of 94% of the water using gravity settling, thus offering a potential application as a low-cost and high-throughput method for primary dewatering of carbohydrate-rich A. platensis.
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decolorisation of piggery wastewater to stimulate the production of Arthrospira platensis
Bioresource Technology, 2013Co-Authors: Orily Depraetere, Imogen Foubert, Koenraad MuylaertAbstract:The aim of this study was to evaluate the potential of color removal methods for enhancing the growth rate and biomass yield of Arthrospira produced using piggery wastewater as a nutrient source. Color could be removed from the piggery wastewater by means of oxidation (H2O2–UV) or by means of positively charged flocculants (e.g., ferric chloride, magnesium hydroxide), biopolymers (chitosan, cationic starch) or adsorbents (hydrotalcite). Some methods remove not only color but also phosphate (e.g., hydrotalcite) while other do not affect phosphate concentrations (e.g., chitosan). Color removal using chitosan resulted in a doubling of initial growth rate and a 50% increase in final biomass yield of Arthrospira produced on piggery wastewater. Color removal using hydrotalcite resulted in a low biomass yield of Arthrospira due to phosphate limitation.
