Articles de revues : « Microalgal culture »

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Gonzalez, Luz E., et Yoav Bashan. « Increased Growth of the Microalga Chlorella vulgariswhen Coimmobilized and Cocultured in Alginate Beads with the Plant-Growth-Promoting Bacterium Azospirillum brasilense ». Applied and Environmental Microbiology 66, n^o 4 (1 avril 2000) : 1527–31. http://dx.doi.org/10.1128/aem.66.4.1527-1531.2000.

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ABSTRACT Coimmobilization of the freshwater microalga Chlorella vulgaris and the plant-growth-promoting bacteriumAzospirillum brasilense in small alginate beads resulted in a significantly increased growth of the microalga. Dry and fresh weight, total number of cells, size of the microalgal clusters (colonies) within the bead, number of microalgal cells per cluster, and the levels of microalgal pigments significantly increased. Light microscopy revealed that both microorganisms colonized the same cavities inside the beads, though the microalgae tended to concentrate in the more aerated periphery while the bacteria colonized the entire bead. The effect of indole-3-acetic acid addition to microalgal culture prior to immobilization of microorganisms in alginate beads partially imitated the effect of A. brasilense. We propose that coimmobilization of microalgae and plant-growth-promoting bacteria is an effective means of increasing microalgal populations within confined environments.

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Wang, Hui, Haywood D. Laughinghouse, Matthew A. Anderson, Feng Chen, Ernest Willliams, Allen R. Place, Odi Zmora, Yonathan Zohar, Tianling Zheng et Russell T. Hill. « Novel Bacterial Isolate from Permian Groundwater, Capable of Aggregating Potential Biofuel-Producing Microalga Nannochloropsis oceanica IMET1 ». Applied and Environmental Microbiology 78, n^o 5 (22 décembre 2011) : 1445–53. http://dx.doi.org/10.1128/aem.06474-11.

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ABSTRACTIncreasing petroleum costs and climate change have resulted in microalgae receiving attention as potential biofuel producers. Little information is available on the diversity and functions of bacterial communities associated with biofuel-producing algae. A potential biofuel-producing microalgal strain,Nannochloropsis oceanicaIMET1, was grown in Permian groundwater. Changes in the bacterial community structure at three temperatures were monitored by two culture-independent methods, and culturable bacteria were characterized. After 9 days of incubation,N. oceanicaIMET1 began to aggregate and precipitate in cultures grown at 30°C, whereas cells remained uniformly distributed at 15°C and 25°C. The bacterial communities in cultures at 30°C changed markedly. Some bacteria isolated only at 30°C were tested for their potential for aggregating microalgae. A novel bacterium designated HW001 showed a remarkable ability to aggregateN. oceanicaIMET1, causing microalgal cells to aggregate after 3 days of incubation, while the total lipid content of the microalgal cells was not affected. Direct interaction of HW001 andN. oceanicais necessary for aggregation. HW001 can also aggregate the microalgaeN. oceanicaCT-1,Tetraselmis suecica, andT. chuiias well as the cyanobacteriumSynechococcusWH8007. 16S rRNA gene sequence comparisons indicated the great novelty of this strain, which exhibited only 89% sequence similarity with any previously cultured bacteria. Specific primers targeted to HW001 revealed that the strain originated from the Permian groundwater. This study of the bacterial communities associated with potential biofuel-producing microalgae addresses a little-investigated area of microalgal biofuel research and provides a novel approach to harvest biofuel-producing microalgae by using the novel bacterium strain HW001.

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Yu, Hyeonjung, Jaai Kim, Chaeyoung Rhee, Juhee Shin, Seung Gu Shin et Changsoo Lee. « Effects of Different pH Control Strategies on Microalgae Cultivation and Nutrient Removal from Anaerobic Digestion Effluent ». Microorganisms 10, n^o 2 (3 février 2022) : 357. http://dx.doi.org/10.3390/microorganisms10020357.

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This study investigated nutrient removal from anaerobic digestion effluent by cultivating mixed-culture microalgae enriched from anaerobic sludge under different pH conditions: RUC (uncontrolled), R7–8 (maintained at 7–8), and R<8 (maintained below 8). Significant amounts of NH4+-N were lost by volatilization in RUC cultures due to increased pH values (≤8.6) during the early period of cultivation. The pH control strategies significantly affected the biological NH4+-N removal (highest in R7–8), microalgal growth (highest in R7–8), biomass settleability (highest in R<8), and microalgal growth relative to bacteria (highest in R<8) in the cultures. Parachlorella completely dominated the microalgal communities in the inoculum and all of the cultures, and grew well at highly acidic pH (<3) induced by culture acidification with microalgal growth. Microalgae-associated bacterial community structure developed very differently among the cultures. The findings call for more attention to the influence and control of pH changes during cultivation in microalgal treatment of anaerobic digestion effluent.

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Postaue, Najla, Leila Cristina Moraes et Rosa Maria Farias Asmus. « CHORUME COMO FONTE DE NUTRIENTE NA PRODUÇÃO DA BIOMASSA MICROALGAL ». e-xacta 12, n^o 2 (9 mars 2020) : 11. http://dx.doi.org/10.18674/exacta.v12i2.2746.

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A biomassa de microalgas tem apresentado potencial para produção de biodiesel, contudo a viabilidade do cultivo de microalgas depende de fonte de nutrientes de baixo custo. O presente estudo objetivou utilizar o chorume como fonte de nutrientes para microalgas. Os experimentos foram conduzidos visando avaliar a obtenção da biomassa microalgal, conversão de lipídios e rendimento em ésteres metílicos de ácidos graxos, para os meios de cultivos utilizando 5%, 12% e 20% de chorume, com concentrações de 0,02, 0,05 e 0,08 g N. L-1 e para meio de controle contendo 1% de, Nitrogênio (N), Fósforo (P) e Potássio (K), na concentração de 20 g L-1, 5 g L-1 e 20 g L-1, respectivamente. A microalga utilizada neste trabalho foi a de classe Chlorophyceae e família Coccomyxaceae. Os resultados demonstraram que o meio com concentração de 12% de chorume obteve melhores resultados, possibilitando alcançar 1,19 g de biomassa, conversão de 108,15 mg g-1 de lipídios e conteúdo de ésteres de 410,77mg g-1, a microalga utilizada apresentou ainda predominância dos ácidos graxos palmítico e oleico, apresentando baixa quantidade de ácidos graxos saturados o que pode fornecer ao combustível, resistência ao frio. E tais aspectos demonstraram que o chorume pode ser uma fonte promissora de nutrientes para o cultivo das microalgas estudadas. AbstractMicroalgae biomass has presented potential for biodiesel production, however the viability of microalgae cultivation depends on low cost nutrient source. The present study aimed to use leachate as a source of nutrients for microalgae. The experiments were conducted to evaluate the microalgal biomass, lipid conversion and yield in fatty acid methyl esters, for the culture media using 5%, 12% and 20% leachate, with concentrations of 0.02, 0.05 and 0.08 g N. L-1 and for control medium containing 1% Nitrogen (N), Phosphorus (P) and Potassium (K), at a concentration of 20 g L-1, 5 g L-1 and 20 g L-1, respectively. The microalgae used in this work was Chlorophyceae class and Coccomyxaceae family. The results showed that the medium with a concentration of 12% of leachate obtained better results, allowing to reach 1.19 g of biomass, conversion of 108.15 mg g-1 of lipids and esters content of 410,77 mg g-1. The microalgae used also presented predominance of palmitic and oleic fatty acids, presenting low amount of saturated fatty acids which can provide the fuel with cold resistance. And these aspects demonstrated that the leachate can be a promising source of nutrients for the cultivation of the studied microalgae.

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Van Anh, Le Thi, Tran Ngoc Anh Thu et Nguyen Thi Dong Phuong. « Investigation of microalgae culture by autoflocculation methodologies ». Vietnam Journal of Biotechnology 20, n^o 3 (30 septembre 2022) : 487–94. http://dx.doi.org/10.15625/1811-4989/17059.

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Harvesting of microalgae from their different cultivation media has pointed out challenges in resolving the problems of flocculation. These challenges must be faced with a suitable method for inducing flocculation that avoid or limit the microalgae’s contamination. This study developed the fundamental experiments with a support of chemicals and some bacteria strains inducing the flocculation of Chlorella vulgaris SAG 211-19. Particularly, the determination of minimum content of Mg2+, Ca2+, E. coli ATCC 85922 and Bacillus subtilis MT300405 was effectuated with co-cultivation of microalgae and set up in batch culture in Bold’s Basal Medium. As a result, the adjustment in 25 minutes of 199.2 mg/L CaCl2.2H2O, 50 mg/L KH2PO4, and of 141 mg/L MgSO4.7H2O induced a microalgal settling efficiency of 81% and 70%, respectively. Meanwhile, the perfomance of microalgal removing reached up to 83.6% and 84% by the inoculation into microalgal culture media of a minimum initial cell density of 8.1 ´ 105 CFU/mL of Bacillus subtilis MT300405 and 12 ´ 105 CFU/mL of E. coli ATCC 85922, respectively. The flocculation of microalgal cells by bacterial inoculation did not require a high pH adjustment as in the case of salt addition.

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Sauvage, Justine, Gary H. Wikfors, Xiaoxu Li, Mark Gluis, Nancy Nevejan, Koen Sabbe et Alyssa Joyce. « Effect of pluronic block polymers and N-acetylcysteine culture media additives on growth rate and fatty acid composition of six marine microalgae species ». Applied Microbiology and Biotechnology 105, n^o 5 (12 février 2021) : 2139–56. http://dx.doi.org/10.1007/s00253-021-11147-8.

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Abstract The efficiency of microalgal biomass production is a determining factor for the economic competitiveness of microalgae-based industries. N-acetylcysteine (NAC) and pluronic block polymers are two compounds of interest as novel culture media constituents because of their respective protective properties against oxidative stress and shear-stress-induced cell damage. Here we quantify the effect of NAC and two pluronic (F127 and F68) culture media additives upon the culture productivity of six marine microalgal species of relevance to the aquaculture industry (four diatoms-Chaetoceros calcitrans, Chaetoceros muelleri, Skeletonema costatum, and Thalassiosira pseudonana; two haptophytes-Tisochrysis lutea and Pavlova salina). Algal culture performance in response to the addition of NAC and pluronic, singly or combined, is dosage- and species-dependent. Combined NAC and pluronic F127 algal culture media additives resulted in specific growth rate increases of 38%, 16%, and 24% for C. calcitrans, C. muelleri, and P. salina, respectively. Enhanced culture productivity for strains belonging to the genus Chaetoceros was paired with an ~27% increase in stationary-phase cell density. For some of the species examined, culture media enrichments with NAC and pluronic resulted in increased omega-3-fatty acid content of the algal biomass. Larval development (i.e., growth and survival) of the Pacific oyster (Crassostrea gigas) was not changed when fed a mixture of microalgae grown in NAC- and F127-supplemented culture medium. Based upon these results, we propose that culture media enrichment with NAC and pluronic F127 is an effective and easily adopted approach to increase algal productivity and enhance the nutritional quality of marine microalgal strains commonly cultured for live-feed applications in aquaculture. Key points • Single and combined NAC and pluronic F127 culture media supplementation significantly enhanced the productivity of Chaetoceros calcitrans and Chaetoceros muelleri cultures. • Culture media enrichments with NAC and F127 can increase omega-3-fatty acid content of algal biomass. • Microalgae grown in NAC- and pluronic F127-supplemented culture media are suitable for live-feed applications.

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Zhang, Xin Ru, Ze Yi Jiang, Hao Yuan, Yuan Xiang Lu, Liang Chen, Ai Hui Chou, Hai Yan et Xin Xin Zhang. « Influence of Surface Zeta Potential on Adhesion of Chlorella sp. to Substratum Surfaces ». Advanced Materials Research 690-693 (mai 2013) : 1431–34. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.1431.

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Microalgae, in wet conditions, tend to grow on surfaces and form biofilms. The adhesion of microalgae to surfaces is very important for algal mass culture. The formation and development of microalgal biofims are in large denpend on the properties of cell surface, substratum surface and gowth medium. In this paper, the influence of substratum surface zeta potential on the microalgal biofilms was particularly investigated. We focused on a widely-used microalgal strain, the freshwater autotrophicChlorella sp..The adhesion phenomena ofChlorella sp.to surfaces with different zeta potential were observed microscopically. It was found thatChlorella sp.adhered easily to the surface with a positive zeta potential and difficultly to the surface with a negative zeta potential. We concluded that the surface zeta potential had a greater influence on the adhesion of microalgal cells to substratum surfaces. Our findings have important implications for microalgae mass culture and harvesting.

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Jeevanandam, Jaison, Mohd Razif Harun, Sie Yon Lau, Divine D. Sewu et Michael K. Danquah. « Microalgal Biomass Generation via Electroflotation : A Cost-Effective Dewatering Technology ». Applied Sciences 10, n^o 24 (18 décembre 2020) : 9053. http://dx.doi.org/10.3390/app10249053.

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Microalgae are an excellent source of bioactive compounds for the production of a wide range of vital consumer products in the biofuel, pharmaceutical, food, cosmetics, and agricultural industries, in addition to huge upstream benefits relating to carbon dioxide biosequestration and wastewater treatment. However, energy-efficient, cost-effective, and scalable microalgal technologies for commercial-scale applications are limited, and this has significantly impacted the full-scale implementation of microalgal biosystems for bioproduct development, phycoremediation, and biorefinery applications. Microalgae culture dewatering continues to be a major challenge to large-scale biomass generation, and this is primarily due to the low cell densities of microalgal cultures and the small hydrodynamic size of microalgal cells. With such biophysical characteristics, energy-intensive solid–liquid separation processes such as centrifugation and filtration are generally used for continuous generation of biomass in large-scale settings, making dewatering a major contributor to the microalgae bioprocess economics. This article analyzes the potential of electroflotation as a cost-effective dewatering process that can be integrated into microalgae bioprocesses for continuous biomass production. Electroflotation hinges on the generation of fine bubbles at the surface of an electrode system to entrain microalgal particulates to the surface. A modification of electroflotation, which combines electrocoagulation to catalyze the coalescence of microalgae cells before gaseous entrainment, is also discussed. A technoeconomic appraisal of the prospects of electroflotation compared with other dewatering technologies is presented.

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Gonzalez-Bashan, Luz E., Vladimir K. Lebsky, Juan P. Hernandez, Jose J. Bustillos et Yoav Bashan. « Changes in the metabolism of the microalga Chlorella vulgaris when coimmobilized in alginate with the nitrogen-fixing Phyllobacterium myrsinacearum ». Canadian Journal of Microbiology 46, n^o 7 (1 juillet 2000) : 653–59. http://dx.doi.org/10.1139/w00-041.

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In an agroindustrial wastewater pond, a naturally occurring unicellular microalga, Chlorella vulgaris, was closely associated with the terrestrial plant-associative N2-fixing bacterium Phyllobacterium myrsinacearum. When the two microorganisms were artificially coimmobilized in alginate beads, they shared the same internal bead cavities, and the production of five microalgal pigments increased, but there were no effects on the number of the cells or the biomass of the microalga. The association, however, reduces the ability of C. vulgaris to remove ammonium ions and phosphorus from water. The bacterium produced nitrate from ammonium in synthetic wastewater with or without the presence of the microalga, and fixed nitrogen in two culture media. Our results suggest that interactions between microalgae and associative bacteria should be considered when cultivating microalgae for wastewater treatment.Key words: alginate, bacterial immobilization, microalgae, nitrogen fixation, Phyllobacterium, wastewater treatment.

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Khaw, Yam Sim, Hui Teng Tan, Arissara Sopawong, Noor Azmi Shaharuddin, Abdul Rahman Omar et Fatimah Md Yusoff. « A Recommendation for a Pre-Standardized Marine Microalgal Dry Weight Determination Protocol for Laboratory Scale Culture Using Ammonium Formate as a Washing Agent ». Biology 10, n^o 8 (19 août 2021) : 799. http://dx.doi.org/10.3390/biology10080799.

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Microalgal biomass is one of the crucial criteria in microalgal studies. Many reported methods, even the well-established protocol on microalgal dry weight (DW) determination, vary greatly, and reliable comparative assessment amongst published results could be problematic. This study aimed to determine the best condition of critical parameters in marine microalgal DW determination for laboratory-scale culture using four different marine microalgal species. These parameters included the washing process, grades of glass microfiber filter (GMF), GMF pretreatment conditions, washing agent (ammonium formate) concentrations, culture: washing agent ratios (v:v) and washing cycles. GMF grade GF/A with precombustion at 450 °C provided the most satisfactory DW and the highest ash-free dry weight (AFDW)/DW ratio. Furthermore, 0.05 M ammonium formate with 1:2 culture: washing agent ratio and a minimum of two washing cycles appeared to be the best settings of microalgal DW determination. The present treatment increased the AFDW/DW ratio of the four respective microalgae by a minimum of 19%. The findings of this study could serve as a pivotal reference in developing a standardized protocol of marine microalgal DW determination to obtain veracious and reliable marine microalgal DW.

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Kovalev, N. N., S. E. Leskova, E. V. Mikheev, Yu M. Pozdnyakova et R. V. Esipenko. « CULTURAL AND BIOCHEMICAL PARAMETERS OF TWO MICROALGAE, PHAEODACTYLUM TRICORNUTUM AND TETRASELMIS SUECIACA, IN CUMULATIVE CULTURES ». Bulletin оf Kamchatka State Technical University, n^o 53 (2020) : 54–65. http://dx.doi.org/10.17217/2079-0333-2020-53-54-65.

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A comparative study of cultural and biochemical parameters of two microalgal species, Tetraselmis sueciaca and Phaeodactylum tricornutum, was performed. Cell density in the storage culture was 2.88 million cells per one ml for T. sueciaca and 20.37 million cells per one ml for Ph. tricornutum. As shown, determination of op-tical density of the culture medium is a more objective characteristic of the cumulative culture growth. For T. sueciaca, cell growth rate during the course of experiment made 400% and for Ph. tricornutum – 700%. Dif-ference in the chemical composition of microalgal biomass was revealed. The microalgae did not differ in their energy value. The prospects of cumulative culture of microalgae in mariculture farms are discussed.

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Wang, Jing Han, Hai Zhen Yang et Feng Wang. « Potential of Mixotrophic Cultivation of Chlorella sorokiniana for Biodiesel Production ». Advanced Materials Research 779-780 (septembre 2013) : 1509–13. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1509.

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Biodiesel from microalgae provides a promising alternative for biofuel production. Microalgal biodiesel can be produced under three major cultivation modes, namely, photoautotrophic, heterotrophic, and mixotrophic cultivation. Studies of biodiesel production from microalgae have been reported mostly focusing on photoautotrophic cultivation, mixotrophic cultivation has rarely been researched. This paper compared the biomass productivity, lipid content, and lipid productivity ofChlorella sorokinianaunder photoautotrophic, heterotrophic, and mixotrophic cultivation. Glucose was adopted as organic carbon source at five concentrations (0.1, 0.5, 1.0, 2.0, 5.0% glucose w/v). Results displayed that microalgal growth was significantly improved in glucose supplied cultures. Synergetic effect of photoautotrophy and heterotrophy existed in mixotrophic cultivation except for 5.0% culture. Highest biomass productivity of 1.178 g·L-1·d-1and highest lipid productivity of 582 mg·L-1·d-1was observed under mixotrophic cultivation with 2.0% (w/v) glucose addition. Lipid content ofC. sorokinianawas mostly higher in stationary phase than in exponential phase. Highest lipid content of 49.37% was observed in 2.0% mixotrophic culture, followed by 47.09% in 2.0% heterotrophic culture.

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Li, Shu Wen, Sheng Jun Luo et Rong Bo Guo. « Influence of Carbon Dioxide Concentration on Microalgal Growth in a Bubble Column Photobioreactor ». Advanced Materials Research 599 (novembre 2012) : 137–40. http://dx.doi.org/10.4028/www.scientific.net/amr.599.137.

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The CO2 sequestration by microalgae is thought to be one of the most sustainable strategies to relieve global warming. To produce 1 ton of microalgal dry biomass, 2 ton of CO2 is required. However, insufficient supply of CO2 will limit microalgal growth, and excessive CO2 both means wasting and inhibits microalgal growth. In the present study, the dissolved CO2 concentration in culture limiting and inhibiting microalgal growth (Chlorella vulgaris) in a bubble column photobioreactor was studied. The experimental results showed that the dissolved CO2 concentration ranging from 107μmol/L to 1500 μmol/L could meet microalgal growth’s need, which provides the guidance for microalgal CO2 biofixation with high efficiency.

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Bertolini, Marta, et Fosca Conti. « Algae Culture Conditions and Process Parameters for Phycoremediation and Biomaterials Production ». Environmental and Climate Technologies 26, n^o 1 (1 janvier 2022) : 1092–105. http://dx.doi.org/10.2478/rtuect-2022-0082.

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Abstract Climate change and increasing world population call for careful utilization of water and energy sources. Microalgae to treat wastewater in a coupled process to produce biofuels and other value-added products for human consumption are promising solutions. An analysis of culture parameters and cultivation processes is presented as essential to achieve economical sustainability from the algae. Results of the activity of microalgal strains in detoxification of wastewater are compared and discussed, particularly in remediation of nitrogen and phosphorous compounds, heavy metal, pharmaceuticals and personal care products. Phycoremediation mechanisms and culture conditions to obtain optimal microalgal growth are discussed. Finally, valuable products that can be produced by microalgae and ecological problems of untreated wastewater are presented.

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Fitriyah, F., Y. Faramitha, D. A. Sari, I. Kresnawaty, T. Panji et D. Santoso. « Improved direct lysis PCR amplification method of microalgal culture for sequencing and species identification ». IOP Conference Series : Earth and Environmental Science 948, n^o 1 (1 décembre 2021) : 012013. http://dx.doi.org/10.1088/1755-1315/948/1/012013.

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Abstract Molecular approach plays important role in species identification for microalgae which involves sequencing of specific DNA barcode present in the genome. This approach involved preparation of template DNA for polymerase chain reaction (PCR) which is time consuming and requires large amounts of algal cells. Microalgal direct PCR have been used frequently for species identification, which simplified the DNA isolation procedure. However, the recent attempts to amplify the rbcL gene of microalga using the previously reported protocol led to poor repeatability. In this study, Nannochloropsis gaditana NIES-2587 was cultured in f/2 liquid medium. The culture growth was estimated on optical density value and the lysis process was improved using gradual temperature procedure during the PCR process. The same culture was extracted using manual DNA extraction method for comparison. The DNA obtained from both methods were amplified using RbclN primer pair to amplify 1486 bp partial sequence of Nannochloropsis rbcL gene, followed by the sequencing of the PCR product. Molecular identification based on the sequence result and BLAST analysis indicated that direct PCR and manual DNA extraction methods successfully produced high sequences result and confirmed the identity of microalgae species into N. gaditana strain CCMP527 with a genetic similarity of >99%.

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Wang, Jing Han, Hai Zhen Yang et Feng Wang. « Mixotrophic Cultivation of Scenedesmus sp. as Biodiesel Feedstock ». Advanced Materials Research 777 (septembre 2013) : 268–73. http://dx.doi.org/10.4028/www.scientific.net/amr.777.268.

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Microalgae are a promising feedstock for biodiesel production. Microalgal biodiesel can be obtained under three major cultivation modes, namely, photoautotrophic, heterotrophic, and mixotrophic cultivation. Reported studies of microalgal biodiesel production are mainly based on photoautotrophic cultivation, mixotrophic cultivation has rarely been researched. This paper compared the biomass productivity, lipid content, and lipid productivity of Scenedesmus sp. under photoautotrophic, heterotrophic, and mixotrophic cultivation. Glucose was added as organic carbon source at five concentrations (0.1, 0.5, 1.0, 2.0, 5.0% glucose w/v). Results displayed that microalgal growth was significantly improved in glucose supplied cultures. Synergetic effect of photoautotrophy and heterotrophy existed in all mixotrophic cultures. Highest biomass productivity of 1.307 g·L-1·d-1 and highest lipid productivity of 316 mg·L-1·d-1 was respectively observed under mixotrophic cultivation with 5.0% and 1.0% (w/v) glucose addition. Lipid content of Scenedesmus sp. under mixotrophic cultivation was mostly higher in stationary phase than in exponential phase. Highest lipid content of 27.73% was observed in 1.0% mixotrophic culture, followed by 24.66% in 1.0% heterotrophic culture.

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Branyikova, Irena, Gita Prochazkova, Tomas Potocar, Zuzana Jezkova et Tomas Branyik. « Harvesting of Microalgae by Flocculation ». Fermentation 4, n^o 4 (9 novembre 2018) : 93. http://dx.doi.org/10.3390/fermentation4040093.

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Due to increasing demands for microalgal biomass and products originating from microalgae, large-scale production systems are necessary. However, current microalgal production technologies are not cost-effective and are hindered by various bottlenecks, one of which is the harvesting of microalgal biomass. Cell separation is difficult because of the low sedimentation velocity of microalgae, their colloidal character with repelling negative surface charges, and low biomass concentrations in culture broths; therefore, large volumes need to be processed in order to concentrate the cells. Flocculation is considered to be one of the most suitable methods for harvesting microalgal biomass. This article provides an overview of flocculation methods suitable for microalgal harvesting, their mechanisms, advantages and drawbacks. Special attention is paid to the role of surface charge in the mechanism of flocculation. The novelty of the review lies in the interconnection between the context of technological applications and physico-chemical surface phenomena.

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Ermis, Hande, Ünzile Güven-Gülhan, Tunahan Çakır et Mahmut Altınbaş. « Microalgae growth and diversity in anaerobic digestate compared to synthetic media ». Biofuel Research Journal 9, n^o 1 (1 mars 2022) : 1551–61. http://dx.doi.org/10.18331/brj2022.9.1.2.

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Economizing microalgal cultivation is a considerable milestone targeted by efforts put into microalgal biorefineries. In light of that, the present study was aimed to explore the potential of using anaerobic liquid digestate (ALD) as culture media to grow microalgae and compared it with three different synthetic media (i.e., N8, BBM, and M8) in terms of biomass yield, fatty acid composition, and nutrient utilization/recovery. Moreover, a mixed culture of wild-type microalgae was employed in this study owing to the ability of mixed cultures to survive extreme conditions, eliminating the risk of losing the culture easily, as it mostly happens with pure cultures. The highest nutrient yield coefficients were achieved when the mixed microalgae culture was cultivated in ALD, where the yield coefficient for nitrogen (YN) and yield coefficient for phosphorus (YP) were 10.7 mg biomass mg-1 N and 98 mg biomass mg-1 P, respectively. The highest lipid content (34%) and the highest concentrations of C16:0 (114 mg L-1) and C18:0 (60.9 mg L-1) were also recorded when the mixed microalgae culture was cultivated in ALD. Furthermore, the polyunsaturated fatty acids (PUFA) content also increased significantly in ALD, a beneficial phenomenon as PUFAs in microalgae allow them to adapt more effectively to extreme conditions. Based on the microbial community analysis performed using the multi-marker metabarcoding approach, Diphylleia rotans, Synechocystis PCC-6803, Cyanobium gracile PCC 6307, and Chlorella sorokiniana were identified as the most abundant species in the ALD growth. Overall, based on the findings of the present study, ALD could be used as a promising cultivation medium for microalgae, offering a process integration approach to combine anaerobic digestion and algae cultivation as an effective way to simultaneously treat the high-strength dark-colored ALD and valorize it into profitable byproducts.

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Hao, Zong Di, Ping Huai Liu, Xun Yang, Jie Shi et Sen Zhang. « Screening Method for Lipid-Content Microalgae Based on Sulfo-Phospho-Vanillin Reaction ». Advanced Materials Research 610-613 (décembre 2012) : 3532–35. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.3532.

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Studies that address the use of microalgae as biofuels often require the frequent measurement of total lipid content. Traditional methods for the quantiﬁcation of lipid are time-consuming or involve the use of expensive analytical equipment that is not available in many labs. Here we investigated microalgal culture as the starting material and simple, colorimetric method for quantitative measurement of neutral lipids in microalgae with a relatively high correlation coefﬁcient (R2=0.9038) between gravimetric and spectrophotometric quantiﬁcation. Linear responses for triolein, vegetable oil and microalgal oil in a concentration range between 0.1 and 1 mg/l were observed. Using this method, Monoraphidium pusillum were screened out of several microalgal strains with the highest lipid content (25.52% dry weight). The color reaction for quantitation of microalgal lipids has significant advantages over traditional methods for screening of high lipid-content strains. Our data implied that the sensitivity and versatility enable this method a useful tool in screening of lipid-content microalgae.

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Tang, Zhixuan, Jiangbing Qiu, Guixiang Wang, Ying Ji, Philipp Hess et Aifeng Li. « Development of an Efficient Extraction Method for Harvesting Gymnodimine-A from Large-Scale Cultures of Karenia selliformis ». Toxins 13, n^o 11 (10 novembre 2021) : 793. http://dx.doi.org/10.3390/toxins13110793.

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Gymnodimine-A (GYM-A) is a fast-acting microalgal toxin and its production of certified materials requires an efficient harvesting technology from the large-scale cultures of toxigenic microalgae. In this study the recoveries of GYM-A were compared between several liquid-liquid extraction (LLE) treatments including solvents, ratios and stirring times to optimize the LLE technique for harvesting GYM-A from Karenia selliformis cultures, of which the dichloromethane was selected as the extractant and added to microalgal cultures at the ratio 55 mL L−1 (5.5%, v/v). The recovery of GYM-A obtained by the LLE technique was also compared with filtration and centrifugation methods. The stability of GYM-A in culture media were also tested under different pH conditions. Results showed that both the conventional filter filtration and centrifugation methods led to fragmentation of microalgal cells and loss of GYM-A in the harvesting processes. A total of 5.1 µg of GYM-A were obtained from 2 L of K. selliformis cultures with a satisfactory recovery of 88%. Interestingly, GYM-A obviously degraded in the culture media with the initial pH 8.2 and the adjusted pH of 7.0 after 7 days, but there was no obvious degradation in the acidic medium at pH 5.0. Therefore, the LLE method developed here permits the collection of large-volume cultures of K. selliformis and the high-efficiency extraction of GYM-A. This work provides a simple and valuable technique for harvesting toxins from large-scale cultures of GYM-producing microalgae.

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Ma, Wei, Chenchen Feng, Fachun Guan, Dianrong Ma et Jinling Cai. « Effective Chlorella vulgaris Biomass Harvesting through Sulfate and Chloride Flocculants ». Journal of Marine Science and Engineering 11, n^o 1 (29 décembre 2022) : 47. http://dx.doi.org/10.3390/jmse11010047.

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Efficient microalgae harvesting is a great challenge hindering diverse industrial applications of microalgae. Flocculation is regarded as an effective and promising technology for microalgae harvesting. In this study, sulfate (Al2(SO4)3 and Fe2(SO4)3) and chloride flocculants (AlCl3 and FeCl3) were used to harvest Chlorella vulgaris. Flocculation conditions, including flocculant dose, flocculation time, stirring speed, stirring time, and flocculation pH, were optimized, and flocculant effects on microalgal cell status, floc characteristics, biomass composition, algal cell re-culture, and media recycling were investigated. All flocculants exhibited efficient flocculation efficiency (93.5–98.8%) with lower doses of sulfate salts (60 mg/L algal culture) and higher doses of chloride salts (100 mg/L algal culture). The tested flocculants had no obvious influence on biomass composition (including lipids, carbohydrates, proteins, and carotenoids), and microalgal cells in flocs could efficiently regrow. The spent medium of all treatments was successfully recycled for subsequent cell growth, thus reducing dependency on fresh medium.

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Araújo, Fabíola Ornellas de, Reinaldo Giudici et João José Martins Simões de Sousa. « CULTIVATION OF THE MICROALGAE CHLORELLA PYRENOIDOSA USING THE PROCESSES OF BIOTECHNOLOGY ». Revista Eletrônica Acervo Científico 2 (26 mars 2019) : 121. http://dx.doi.org/10.25248/reac.e121.2019.

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The results obtained here, show that the use of Chlorella pyrenoidosa microalgae and biotechnology, using the discontinuous process, presented satisfactory results. With this, the study of the microalga Chlorella sp. has proved to be important because it has a wealth of proteins, carbohydrates, amino acids, fatty acids, carotenoids, vitamins and minerals in its constitution, which may represent commercial importance. This research revealed the best results for obtaining a lipoprotein-rich biomass, taking into account three different culture media, calculations of cell concentration, cell productivity, to the content (%) of protein, lipid, carbohydrate and ash present in the microalgal biomass.

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Journal, Baghdad Science. « Microalgae Chlorella Vulgaris Harvesting Via Co-Pelletization with Filamentous Fungus ». Baghdad Science Journal 15, n^o 1 (4 mars 2018) : 31–36. http://dx.doi.org/10.21123/bsj.15.1.31-36.

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The objective of this study was to progress another method for coagulation/flocculation of the microalga Chlorella vulgaris via pellet-forming of the fungal species Aspergillus niger which was isolated from municipal wastewater mud and the facultative heterotrophic microalga "C.vulgaris was used. The main factors studies were spore inoculums, organic carbon concentration in medium as well as pH variation which had considerably positive effects on microalgae/fungi co-pelletization formation. The process parameters are an inoculum1×104 spores/ML, 15 g/l sucrose as carbon source and pH ranged from 5 - 7.0 were found optimal for efficient microalgae/fungi co-pelletization formation. For autotrophic growth, when pH of culture broth was adjusted to 5.0 -7.0 with organic carbon addition (15 g/L sucrose), almost complete harvesting efficiency of the microalga was achieved. Furthermore, it was observed that diameter and the concentration of microalgae/fungi pellets were pretentious by the shaker rotation. The new harvesting technology established in this study will decrease the microalga harvesting cost and will be possible to adapt this technique to all microalgal species as an alternative to other old-style harvesting approaches.

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Sirohi, Priyanka, Hariom Verma, Sandeep Kumar Singh, Vipin Kumar Singh, Jyoti Pandey, Saksham Khusharia, Dharmendra Kumar, Kaushalendra, Pratibha Teotia et Ajay Kumar. « Microalgal Carotenoids : Therapeutic Application and Latest Approaches to Enhance the Production ». Current Issues in Molecular Biology 44, n^o 12 (9 décembre 2022) : 6257–79. http://dx.doi.org/10.3390/cimb44120427.

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Microalgae are microscopic photosynthetic organisms frequently found in fresh and marine water ecosystems. Various microalgal species have been considered a reservoir of diverse health-value products, including vitamins, proteins, lipids, and polysaccharides, and are broadly utilized as food and for the treatment of human ailments such as cancer, cardiovascular diseases, allergies, and immunodeficiency. Microalgae-derived carotenoids are the type of accessory pigment that possess light-absorbing potential and play a significant role in metabolic functions. To date, nearly a thousand carotenoids have been reported, but a very less number of microalgae have been used for the commercial production of carotenoids. This review article briefly discussed the carotenoids of microalgal origin and their therapeutic application. In addition, we have briefly compiled the optimization of culture parameters used to enhance microalgal carotenoid production. In addition, the latest biotechnological approaches used to improve the yields of carotenoid has also been discussed.

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Plyusnina, Tatiana Yu, Sergei S. Khruschev, Polina V. Fursova, Alexei E. Solovchenko, Taras K. Antal, Galina Yu Riznichenko et Andrei B. Rubin. « Simulating the Interplay between the Uptake of Inorganic Phosphate and the Cell Phosphate Metabolism under Phosphorus Feast and Famine Conditions in Chlorella vulgaris ». Cells 10, n^o 12 (17 décembre 2021) : 3571. http://dx.doi.org/10.3390/cells10123571.

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Using a mathematical simulation approach, we studied the dynamics of the green microalga Chlorella vulgaris phosphate metabolism response to shortage and subsequent replenishing of inorganic phosphate in the medium. A three-pool interaction model was used to describe the phosphate uptake from the medium, its incorporation into the cell organic compounds, its storage in the form of polyphosphates, and culture growth. The model comprises a system of ordinary differential equations. The distribution of phosphorous between cell pools was examined for three different stages of the experiment: growth in phosphate-rich medium, incubation in phosphate-free medium, and phosphate addition to the phosphorus-starving culture. Mathematical modeling offers two possible scenarios for the appearance of the peak of polyphosphates (PolyP). The first scenario explains the accumulation of PolyP by activation of the processes of its synthesis, and the decline in PolyP is due to its redistribution between dividing cells during growth. The second scenario includes a hysteretic mechanism for the regulation of PolyP hydrolysis, depending on the intracellular content of inorganic phosphate. The new model of the dynamics of P pools in the cell allows one to better understand the phenomena taking place during P starvation and re-feeding of the P-starved microalgal cultures with inorganic phosphate such as transient PolyP accumulation. Biotechnological implications of the observed dynamics of the polyphosphate pool of the microalgal cell are considered. An approach enhancing the microalgae-based wastewater treatment method based on these scenarios is proposed.

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Fuentes, Juan-Luis, Zaida Montero, María Cuaresma, Mari-Carmen Ruiz-Domínguez, Benito Mogedas, Inés Garbayo Nores, Manuel González del Valle et Carlos Vílchez. « Outdoor Large-Scale Cultivation of the Acidophilic Microalga Coccomyxa onubensis in a Vertical Close Photobioreactor for Lutein Production ». Processes 8, n^o 3 (10 mars 2020) : 324. http://dx.doi.org/10.3390/pr8030324.

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The large-scale biomass production is an essential step in the biotechnological applications of microalgae. Coccomyxa onubensis is an acidophilic microalga isolated from the highly acidic waters of Río Tinto (province of Huelva, Spain) and has been shown to accumulate a high concentration of lutein (9.7 mg g−1dw), a valuable antioxidant, when grown at laboratory-scale. A productivity of 0.14 g L−1 d−1 was obtained by growing the microalga under outdoor conditions in an 800 L tubular photobioreactor. The results show a stable biomass production for at least one month and with a lutein content of 10 mg g−1dw, at pH values in the range 2.5–3.0 and temperature in the range 10–25 °C. Culture density, temperature, and CO2 availability in highly acidic medium are rate-limiting conditions for the microalgal growth. These aspects are discussed in this paper in order to improve the outdoor culture conditions for competitive applications of C. onubensis.

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Moreira, Juliana Botelho, Suelen Goettems Kuntzler, Priscilla Quenia Muniz Bezerra, Ana Paula Aguiar Cassuriaga, Munise Zaparoli, Jacinta Lutécia Vitorino da Silva, Jorge Alberto Vieira Costa et Michele Greque de Morais. « Recent Advances of Microalgae Exopolysaccharides for Application as Bioflocculants ». Polysaccharides 3, n^o 1 (8 mars 2022) : 264–76. http://dx.doi.org/10.3390/polysaccharides3010015.

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Microalgae are used in flocculation processes because biopolymers are released into the culture medium. Microalgal cell growth under specific conditions (temperature, pH, luminosity, nutrients, and salinity) provides the production and release of exopolysaccharides (EPS). These biopolymers can be recovered from the medium for application as bioflocculants or used directly in cultivation as microalgae autoflocculants. The optimization of nutritional parameters, the control of process conditions, and the possibility of scaling up allow the production and industrial application of microalgal EPS. Therefore, this review addresses the potential use of EPS produced by microalgae in bioflocculation. The recovery, determination, and quantification techniques for these biopolymers are also addressed. Moreover, other technological applications of EPS are highlighted.

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de Morais, Michele Greque, Bruna da Silva Vaz, Etiele Greque de Morais et Jorge Alberto Vieira Costa. « Biologically Active Metabolites Synthesized by Microalgae ». BioMed Research International 2015 (2015) : 1–15. http://dx.doi.org/10.1155/2015/835761.

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Microalgae are microorganisms that have different morphological, physiological, and genetic traits that confer the ability to produce different biologically active metabolites. Microalgal biotechnology has become a subject of study for various fields, due to the varied bioproducts that can be obtained from these microorganisms. When microalgal cultivation processes are better understood, microalgae can become an environmentally friendly and economically viable source of compounds of interest, because production can be optimized in a controlled culture. The bioactive compounds derived from microalgae have anti-inflammatory, antimicrobial, and antioxidant activities, among others. Furthermore, these microorganisms have the ability to promote health and reduce the risk of the development of degenerative diseases. In this context, the aim of this review is to discuss bioactive metabolites produced by microalgae for possible applications in the life sciences.

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Li, Jiawei, Xinqing Zhao, Jo-Shu Chang et Xiaoling Miao. « A Two-Stage Culture Strategy for Scenedesmus sp. FSP3 for CO2 Fixation and the Simultaneous Production of Lutein under Light and Salt Stress ». Molecules 27, n^o 21 (3 novembre 2022) : 7497. http://dx.doi.org/10.3390/molecules27217497.

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In this study, Scenedesmus sp. FSP3 was cultured using a two-stage culture strategy for CO2 fixation and lutein production. During the first stage, propylene carbonate was added to the medium, with 5% CO2 introduced to promote the rapid growth and CO2 fixation of the microalgae. During the second stage of cultivation, a NaCl concentration of 156 mmol L−1 and a light intensity of 160 μmol m−2 s−1 were used to stimulate the accumulation of lutein in the microalgal cells. By using this culture method, high lutein production and CO2 fixation were simultaneously achieved. The biomass productivity and carbon fixation rate of Scenedesmus sp. FSP3 reached 0.58 g L−1 d−1 and 1.09 g L−1 d−1, with a lutein content and yield as high as 6.45 mg g−1 and 2.30 mg L−1 d−1, respectively. The results reveal a commercially feasible way to integrate microalgal lutein production with CO2 fixation processes.

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Babiak, Wioleta, et Izabela Krzemińska. « Extracellular Polymeric Substances (EPS) as Microalgal Bioproducts : A Review of Factors Affecting EPS Synthesis and Application in Flocculation Processes ». Energies 14, n^o 13 (2 juillet 2021) : 4007. http://dx.doi.org/10.3390/en14134007.

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Microalgae are natural resources of intracellular compounds with a wide spectrum of applications in, e.g., the food industry, pharmacy, and biofuel production. The extracellular polymeric substances (EPS) released by microalgal cells are a valuable bioproduct. Polysaccharides, protein, lipids, and DNA are the main constituents of EPS. This review presents the recent advances in the field of the determinants of the synthesis of extracellular polymeric substances by microalgal cells and the EPS structure. Physical and chemical culture conditions have been analyzed to achieve useful insights into the development of a strategy optimizing EPS production by microalgal cells. The application of microalgal EPS for flocculation and mechanisms involved in this process are also discussed in terms of biomass harvesting. Additionally, the ability of EPS to remove toxic heavy metals has been analyzed. With their flocculation and sorption properties, microalgal EPS are a promising bioproduct that can potentially be used in harvesting algal biomass and wastewater management.

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Iasimone, F., G. Zuccaro, V. D'Oriano, G. Franci, M. Galdiero, D. Pirozzi, V. De Felice et F. Pirozzi. « Combined yeast and microalgal cultivation in a pilot-scale raceway pond for urban wastewater treatment and potential biodiesel production ». Water Science and Technology 77, n^o 4 (14 décembre 2017) : 1062–71. http://dx.doi.org/10.2166/wst.2017.620.

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Abstract A mixed culture of oleaginous yeast Lipomyces starkeyi and wastewater native microalgae (mostly Scenedesmus sp. and Chlorella sp.) was performed to enhance lipid and biomass production from urban wastewaters. A 400 L raceway pond, operating outdoors, was designed and used for biomass cultivation. Microalgae and yeast were inoculated into the cultivation pond with a 2:1 inoculum ratio. Their concentrations were monitored for 14 continuous days of batch cultivation. Microalgal growth presented a 3-day initial lag-phase, while yeast growth occurred in the first few days. Yeast activity during the microalgal lag-phase enhanced microalgal biomass productivity, corresponding to 31.4 mgTSS m−2 d−1. Yeast growth was limited by low concentrations in wastewater of easily assimilated organic substrates. Organic carbon was absorbed in the first 3 days with a 3.7 mgC L−1 d−1 removal rate. Complete nutrient removal occurred during microalgal linear growth with 2.9 mgN L−1 d−1 and 0.96 mgP L−1 d−1 removal rates. Microalgal photosynthetic activity induced high pH and dissolved oxygen values resulted in natural bactericidal and antifungal activity. A 15% lipid/dry weight was measured at the end of the cultivation time. Fatty acid methyl ester (FAME) analysis indicated that the lipids were mainly composed of arachidic acid.

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Ortiz-Marquez, Juan Cesar Federico, Mauro Do Nascimento, Maria de los Angeles Dublan et Leonardo Curatti. « Association with an Ammonium-Excreting Bacterium Allows Diazotrophic Culture of Oil-Rich Eukaryotic Microalgae ». Applied and Environmental Microbiology 78, n^o 7 (20 janvier 2012) : 2345–52. http://dx.doi.org/10.1128/aem.06260-11.

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ABSTRACTConcerns regarding the depletion of the world's reserves of oil and global climate change have promoted an intensification of research and development toward the production of biofuels and other alternative sources of energy during the last years. There is currently much interest in developing the technology for third-generation biofuels from microalgal biomass mainly because of its potential for high yields and reduced land use changes in comparison with biofuels derived from plant feedstocks. Regardless of the nature of the feedstock, the use of fertilizers, especially nitrogen, entails a potential economic and environmental drawback for the sustainability of biofuel production. In this work, we have studied the possibility of nitrogen biofertilization by diazotrophic bacteria applied to cultured microalgae as a promising feedstock for next-generation biofuels. We have obtained anAzotobacter vinelandiimutant strain that accumulates several times more ammonium in culture medium than wild-type cells. The ammonium excreted by the mutant cells is bioavailable to promote the growth of nondiazotrophic microalgae. Moreover, this synthetic symbiosis was able to produce an oil-rich microalgal biomass using both carbon and nitrogen from the air. This work provides a proof of concept that artificial symbiosis may be considered an alternative strategy for the low-N-intensive cultivation of microalgae for the sustainable production of next-generation biofuels and other bioproducts.

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Barua, Visva Bharati, et Mariya Munir. « A Review on Synchronous Microalgal Lipid Enhancement and Wastewater Treatment ». Energies 14, n^o 22 (17 novembre 2021) : 7687. http://dx.doi.org/10.3390/en14227687.

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Microalgae are unicellular photosynthetic eukaryotes that can treat wastewater and provide us with biofuel. Microalgae cultivation utilizing wastewater is a promising approach for synchronous wastewater treatment and biofuel production. However, previous studies suggest that high microalgae biomass production reduces lipid production and vice versa. For cost-effective biofuel production from microalgae, synchronous lipid and biomass enhancement utilizing wastewater is necessary. Therefore, this study brings forth a comprehensive review of synchronous microalgal lipid and biomass enhancement strategies for biofuel production and wastewater treatment. The review emphasizes the appropriate synergy of the microalgae species, culture media, and synchronous lipid and biomass enhancement conditions as a sustainable, efficient solution.

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Savio, Saverio, Corrado di Natale, Roberto Paolesse, Larisa Lvova et Roberta Congestri. « Keeping Track of Phaeodactylum tricornutum (Bacillariophyta) Culture Contamination by Potentiometric E-Tongue ». Sensors 21, n^o 12 (12 juin 2021) : 4052. http://dx.doi.org/10.3390/s21124052.

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The large-scale cultivation of microalgae provides a wide spectrum of marketable bioproducts, profitably used in many fields, from the preparation of functional health products and feed supplement in aquaculture and animal husbandry to biofuels and green chemistry agents. The commercially successful algal biomass production requires effective strategies to maintain the process at desired productivity and stability levels. Hence, the development of effective early warning methods to timely indicate remedial actions and to undertake countermeasures is extremely important to avoid culture collapse and consequent economic losses. With the aim to develop an early warning method of algal contamination, the potentiometric E-tongue was applied to record the variations in the culture environments, over the whole growth process, of two unialgal cultures, Phaeodactylum tricornutum and a microalgal contaminant, along with those of their mixed culture. The E-tongue system ability to distinguish the cultures and to predict their growth stage, through the application of multivariate data analysis, was shown. A PLS regression method applied to the E-tongue output data allowed a good prediction of culture growth time, expressed as growth days, with R2 values in a range from 0.913 to 0.960 and RMSEP of 1.97–2.38 days. Moreover, the SIMCA and PLS-DA techniques were useful for cultures contamination monitoring. The constructed PLS-DA model properly discriminated 67% of cultures through the analysis of their growth media, i.e., environments, thus proving the potential of the E-tongue system for a real time monitoring of contamination in microalgal intensive cultivation.

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Marazzi, Francesca, Micol Bellucci, Tania Fantasia, Elena Ficara et Valeria Mezzanotte. « Interactions between Microalgae and Bacteria in the Treatment of Wastewater from Milk Whey Processing ». Water 12, n^o 1 (19 janvier 2020) : 297. http://dx.doi.org/10.3390/w12010297.

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Milk whey processing wastewaters (MWPWs) are characterized by high COD and organic nitrogen content; the concentrations of phosphorus are also relevant. A microalgal-based process was tested at lab scale in order to assess the feasibility of treating MWPW without any dilution or pre-treatment. Different microalgal strains and populations were tested. Based on the obtained results, Scenedesmus acuminatus (SA) and a mixed population (PM) chiefly made of Chlorella, Scenedesmus, and Chlamydomonas spp. were grown in duplicate for 70 days in Plexiglas column photobioreactors (PBRs), fed continuously (2.5 L culture volume, 7 days hydraulic retention time). Nutrient removal, microalgae growth, photosynthetic efficiency, and the composition of microalgal populations in the columns were monitored. At steady state, the microalgal growth was similar for SA and PM. The average removal efficiencies for the main pollutants were: 93% (SA), 94% (PM) for COD; 88% (SA) and 90% (PM) for total N; and 69% (SA) and 73% (PM) for total P. The residual pollution levels in the effluent from the PBRs were low enough to allow their discharge into surface waters; such good results were achieved thanks to the synergy between the microalgae and bacteria in the CO2 and oxygen production/consumption and in the nitrogen mineralization.

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Stemmler, Kevin, Rebecca Massimi et Andrea E. Kirkwood. « Growth and fatty acid characterization of microalgae isolated from municipal waste-treatment systems and the potential role of algal-associated bacteria in feedstock production ». PeerJ 4 (7 mars 2016) : e1780. http://dx.doi.org/10.7717/peerj.1780.

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Much research has focused on growing microalgae for biofuel feedstock, yet there remain concerns about the feasibility of freshwater feedstock systems. To reduce cost and improve environmental sustainability, an ideal microalgal feedstock system would be fed by municipal, agricultural or industrial wastewater as a main source of water and nutrients. Nonetheless, the microalgae must also be tolerant of fluctuating wastewater quality, while still producing adequate biomass and lipid yields. To address this problem, our study focused on isolating and characterizing microalgal strains from three municipal wastewater treatment systems (two activated sludge and one aerated-stabilization basin systems) for their potential use in biofuel feedstock production. Most of the 19 isolates from wastewater grew faster than two culture collection strains under mixotrophic conditions, particularly with glucose. The fastest growing wastewater strains included the generaChlorellaandDictyochloris. The fastest growing microalgal strains were not necessarily the best lipid producers. Under photoautotrophic and mixotrophic growth conditions, single strains ofChlorellaandScenedesmuseach produced the highest lipid yields, including those most relevant to biodiesel production. A comparison of axenic and non-axenic versions of wastewater strains showed a notable effect of commensal bacteria on fatty acid composition. Strains grown with bacteria tended to produce relatively equal proportions of saturated and unsaturated fatty acids, which is an ideal lipid blend for biodiesel production. These results not only show the potential for using microalgae isolated from wastewater for growth in wastewater-fed feedstock systems, but also the important role that commensal bacteria may have in impacting the fatty acid profiles of microalgal feedstock.

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Supono, Supono, Maria Mugica, Stefan Spreitzenbarth et Andrew Jeffs. « Potential for Concentrated Microalgae as Replacement Diets for Juvenile Green-Lipped Mussels, Perna canaliculus ». Aquaculture Research 2023 (21 février 2023) : 1–9. http://dx.doi.org/10.1155/2023/9841172.

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The nursery culture of bivalves typically relies on the feeding of costly live microalgae, while the use of natural sources of phytoplankton for feed is uncertain due to their variable quality and abundance. Replacement diets have been applied in bivalve nursery culture to replace live microalgae with varying success. This study investigated the potential use of two concentrated microalgal diets at a range of levels of substitution with live microalgae. Shellfish Diet 1800® (called SD) and LPB™ Frozen Shellfish Diet® (called LPB) were fed to juvenile green-lipped mussels (Perna canaliculus) at five levels of substitution for live microalgae (i.e., 0, 25, 50, 75, and 100%) for 27 days. The mortality of mussels fed with 100% LPB replacement was significantly higher than the mortality of mussels fed at the lower levels of replacement, i.e., 0 and 25%. The overall final size of spat tended to decrease with the increasing level replacement of live microalgae. Proximate analysis (i.e., crude ash-free dry weight, crude protein, crude lipid, and carbohydrate) showed that only the proportion of carbohydrate content of spat was influenced by feeding treatments, with the mean total carbohydrate content of mussels tending to decrease with increasing levels of replacement of live microalgae. The results indicate that both concentrated microalgal feeds (SD and LPB) are effective at replacing live microalgae by up to 50% without compromising the survival and nutritional profile (AFDW, protein, lipid, and carbohydrate content) of juvenile green-lipped mussels and are therefore a useful resource for improving the efficiency of production.

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Zieliński, Marcin, Marcin Dębowski et Joanna Kazimierowicz. « Outflow from a Biogas Plant as a Medium for Microalgae Biomass Cultivation—Pilot Scale Study and Technical Concept of a Large-Scale Installation ». Energies 15, n^o 8 (15 avril 2022) : 2912. http://dx.doi.org/10.3390/en15082912.

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Microalgae-based technologies have huge potential for application in the environment sector and the bio-energy industry. However, their cost-efficiency has to be improved by drawing on design and operation data for large-scale installations. This paper presents a technical concept of an installation for large-scale microalgae culture on digestate liquor, and the results of a pilot-scale study to test its performance. The quality of non-treated digestate has been shown to be insufficient for direct use as a growth medium due to excess suspended solids, turbidity, and organic matter content, which need to be reduced. To that end, this paper proposes a system based on mechanical separation, flotation, and pre-treatment on a biofilter. The culture medium fed into photobioreactors had the following parameters after the processing: COD—340 mgO2/dm3, BOD5—100 mgO2/dm3, TN—900 mg/dm3, and TP—70 mg/dm3. The installation can produce approx. 720 kgVS/day of microalgal biomass. A membrane unit and a thickening centrifuge (thickener) were incorporated into the design to separate and dehydrate the microalgal biomass, respectively. The total energy consumption approximated 1870 kWh/day.

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DeWreede, Robert E. « SEAWEEDS, MARINE AQUACULTURE, AND MICROALGAL CULTURE ». Journal of Phycology 40, n^o 5 (octobre 2004) : 998. http://dx.doi.org/10.1111/j.1529-8817.2004.40503.x.

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Avsiyan, Anna L., et Alexander S. Lelekov. « Dependence of microalgae culture specific endogenous loss rate and gross productivity on irradiance ». Issues of modern algology (Вопросы современной альгологии), n^o 1(22) (2020) : 8–16. http://dx.doi.org/10.33624/2311-0147-2020-1(22)-8-16.

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Microalgal growth rate is determined by the difference between gross productivity and endogenous biomass loss rate. Gross productivity is a function of surface irradiance and reaches the maximal value under saturating light intensity. Endogenous biomass consumption of microalgal cells is mainly due to the respiration which can be sub-divided into growth and maintenance respiration. The paper proposes equations for calculating microalgae culture gross productivity and specific loss rate based on production characteristics. Verification of the obtained equations was performed for Arthrospira platensis and Dunaliella salina cultivated under constant illumination with different irradiance. It was demonstrated that gross productivity and specific loss rate increase linearly with increasing irradiance. Specific loss rate varied from 0,01 to 0,58 h-1 in A. platensis and from 0,04 to 0,35 day-1 in D. salina. Specific maintenance respiration rate was determined to be 0,01 h-1 in A. platensis and 0,01–0,04 day-1 in D. salina. The proposed calculation method enables a sufficiently accurate determination of productivity and loss rates based on culture density dynamics measures.

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Hung, Ha Vinh. « RESEARCH ON HARVESTING OF MICROALGAE CHLORELLA SP. BY ELECTROCHEMICAL FLOTATION METHOD USING CORROSIVE ELECTRODES ». Vietnam Journal of Science and Technology 55, n^o 4C (24 mars 2018) : 14. http://dx.doi.org/10.15625/2525-2518/55/4c/12123.

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Microalgae are a promising feedstock for biodiesel production. Harvesting of microalgal biomass is still a bottleneck to its commercial scale application, due to small cell size, low culture densities, colloidal stability and thus economic disadvantage. The aim of this study was to evaluate the biomass separation of the small size microalgae Chlorella sp. by electrochemical flotation process with rectangle electrodes using aluminum or iron plates. The most effective conditions for this experiment involved the use of an aluminum electrode for 30 min with a current density of 1.5 mA/cm2, whereas the iron electrode has been used ineffectively with the same of conditions. The effect of current density (0.5–3 mA/cm2), concentration of microalgae biomass (0.29–1.5 g/L), and electrolyte (0–2 g/L) for aluminum electrode were analyzed. The highest recovery efficiency of 90 % was obtained for Chlorella sp. at 1.5 mA/cm2 in 30 min and concentration of microalgae biomass of 0.74 - 1.5 g/L with power consumption of 1.36 kWh/kg. The electrochemical flotation process with aluminum electrodes could be a possible harvesting step at commercial scale for microalgal biomass production.

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Jo, Seung-Woo, Jeong-Mi Do, Ho Na, Ji Won Hong, Il-Sup Kim et Ho-Sung Yoon. « Assessment of biomass potentials of microalgal communities in open pond raceways using mass cultivation ». PeerJ 8 (16 juillet 2020) : e9418. http://dx.doi.org/10.7717/peerj.9418.

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Metagenome studies have provided us with insights into the complex interactions of microorganisms with their environments and hosts. Few studies have focused on microalgae-associated metagenomes, and no study has addressed aquatic microalgae and their bacterial communities in open pond raceways (OPRs). This study explored the possibility of using microalgal biomasses from OPRs for biodiesel and biofertilizer production. The fatty acid profiles of the biomasses and the physical and chemical properties of derived fuels were evaluated. In addition, the phenotype-based environmental adaptation ability of soybean plants was assessed. The growth rate, biomass, and lipid productivity of microalgae were also examined during mass cultivation from April to November 2017. Metagenomics analysis using MiSeq identified ∼127 eukaryotic phylotypes following mass cultivation with (OPR 1) or without (OPR 3) a semitransparent film. Of these, ∼80 phylotypes were found in both OPRs, while 23 and 24 phylotypes were identified in OPRs 1 and 3, respectively. The phylotypes belonged to various genera, such as Desmodesmus, Pseudopediastrum, Tetradesmus, and Chlorella, of which, the dominant microalgal species was Desmodesmus sp. On average, OPRs 1 and 3 produced ∼8.6 and 9.9 g m−2 d−1 (0.307 and 0.309 DW L−1) of total biomass, respectively, of which 14.0 and 13.3 wt% respectively, was lipid content. Fatty acid profiling revealed that total saturated fatty acids (mainly C16:0) of biodiesel obtained from the microalgal biomasses in OPRs 1 and 3 were 34.93% and 32.85%, respectively; total monounsaturated fatty acids (C16:1 and C18:1) were 32.40% and 31.64%, respectively; and polyunsaturated fatty acids (including C18:3) were 32.68% and 35.50%, respectively. Fuel properties determined by empirical equations were within the limits of biodiesel standards ASTM D6751 and EN 14214. Culture solutions with or without microalgal biomasses enhanced the environmental adaptation ability of soybean plants, increasing their seed production. Therefore, microalgal biomass produced through mass cultivation is excellent feedstock for producing high-quality biodiesel and biofertilizer.

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Macdonald Miller, Sean, Raffaela M. Abbriano, Anna Segecova, Andrei Herdean, Peter J. Ralph et Mathieu Pernice. « Comparative Study Highlights the Potential of Spectral Deconvolution for Fucoxanthin Screening in Live Phaeodactylum tricornutum Cultures ». Marine Drugs 20, n^o 1 (23 décembre 2021) : 19. http://dx.doi.org/10.3390/md20010019.

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

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Policastro, Grazia, Alessandra Cesaro, Massimiliano Fabbricino et Francesco Pirozzi. « Opportunities and Challenges from Symbiosis of Agro-Industrial Residue Anaerobic Digestion with Microalgae Cultivation ». Sustainability 14, n^o 23 (23 novembre 2022) : 15607. http://dx.doi.org/10.3390/su142315607.

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During the last few years, many studies have tested microalgal systems for nitrogen removal from the digestate. However, most of these studies were carried out using pure culture microalgal strains, which require aseptic conditions and thus cannot be used in full-scale applications. The aim of the present study was to explore opportunities in and challenges of the industrial symbiosis of anaerobic digestion and microalgae cultivation to enhance agro-industrial residue management. Batch tests were carried out to investigate the use of a mixed (open) microalgal consortium to treat the liquid fraction of the digestate for nitrogen removal. Preliminary experiments were performed to choose the carbon supply condition optimizing the growth of the open mixed consortium. In detail, the investigated carbon sources were bicarbonate, under two different carbon to nitrogen ratios, CO2 via the free surface and CO2 via air flushing. Further tests were conducted to compare the use of ammoniacal and nitric nitrogen sources. Then, the effectiveness of the liquid fraction of the digestate as nitrogen source was assessed. The highest biomass concentration of 1.6 g L−1 was obtained using CO2 as carbon source via air flushing as feeding strategy and ammoniacal nitrogen. Biomass production was lower (0.6 g L−1) under the digestate. Nonetheless, due to a probable symbiosis between microalgae and bacteria, a total nitrogen removal of 98.5% was achieved, which was the highest obtained in the present study. Such experimental results address the identification of the steps needed for larger-scale application of combined anaerobic digestion and mixed microalgal systems.

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Khaw, Yam Sim, Fatimah Md Yusoff, Hui Teng Tan, Nur Amirah Izyan Noor Mazli, Muhammad Farhan Nazarudin, Noor Azmi Shaharuddin, Abdul Rahman Omar et Kazutaka Takahashi. « Fucoxanthin Production of Microalgae under Different Culture Factors : A Systematic Review ». Marine Drugs 20, n^o 10 (22 septembre 2022) : 592. http://dx.doi.org/10.3390/md20100592.

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Fucoxanthin is one of the light-harvesting pigments in brown microalgae, which is increasingly gaining attention due to its numerous health-promoting properties. Currently, the production of microalgal fucoxanthin is not yet feasible from an economic perspective. However, the cultivation of microalgae at favourable conditions holds great potential to increase the viability of this fucoxanthin source. Hence, this study aimed to review the fucoxanthin production of microalgae under different conditions systematically. A literature search was performed using the Web of Science, Scopus and PubMed databases. A total of 188 articles were downloaded and 28 articles were selected for the current review by two independent authors. Microalgae appeared to be a more reliable fucoxanthin source compared to macroalgae. Overall, a consensus fucoxanthin production condition was obtained and proposed: light intensity ranging from 10 to 100 µmol/m2/s could achieve a higher fucoxanthin content. However, the optimal light condition in producing fucoxanthin is species-specific. The current review serves as an antecedent by offering insights into the fucoxanthin-producing microalgae response to different culture factors via a systematic analysis. With the current findings and recommendations, the feasibility of producing fucoxanthin commercially could be enhanced and possibly achieve practical and sustainable fucoxanthin production.

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Greenwell, H. C., L. M. L. Laurens, R. J. Shields, R. W. Lovitt et K. J. Flynn. « Placing microalgae on the biofuels priority list : a review of the technological challenges ». Journal of The Royal Society Interface 7, n^o 46 (23 décembre 2009) : 703–26. http://dx.doi.org/10.1098/rsif.2009.0322.

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Microalgae provide various potential advantages for biofuel production when compared with ‘traditional’ crops. Specifically, large-scale microalgal culture need not compete for arable land, while in theory their productivity is greater. In consequence, there has been resurgence in interest and a proliferation of algae fuel projects. However, while on a theoretical basis, microalgae may produce between 10- and 100-fold more oil per acre, such capacities have not been validated on a commercial scale. We critically review current designs of algal culture facilities, including photobioreactors and open ponds, with regards to photosynthetic productivity and associated biomass and oil production and include an analysis of alternative approaches using models, balancing space needs, productivity and biomass concentrations, together with nutrient requirements. In the light of the current interest in synthetic genomics and genetic modifications, we also evaluate the options for potential metabolic engineering of the lipid biosynthesis pathways of microalgae. We conclude that although significant literature exists on microalgal growth and biochemistry, significantly more work needs to be undertaken to understand and potentially manipulate algal lipid metabolism. Furthermore, with regards to chemical upgrading of algal lipids and biomass, we describe alternative fuel synthesis routes, and discuss and evaluate the application of catalysts traditionally used for plant oils. Simulations that incorporate financial elements, along with fluid dynamics and algae growth models, are likely to be increasingly useful for predicting reactor design efficiency and life cycle analysis to determine the viability of the various options for large-scale culture. The greatest potential for cost reduction and increased yields most probably lies within closed or hybrid closed–open production systems.

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Nguyen, Hong Hai, Hong Ngoc Luong, Ngoc Kim Qui Nguyen, Le Phuong Uyen Nguyen, Phuong Thao Nguyen, Cong Sac Tran et Xuan Thanh Bui. « Effects of settling time on the flocculation progress and treatment performance in the co-culture of microalgae-activated sludge photobioreactor ». Ministry of Science and Technology, Vietnam 64, n^o 4 (15 décembre 2022) : 91–95. http://dx.doi.org/10.31276/vjste.64(4).91-95.

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The application of microalgae-based wastewater treatment systems using wastewater as a source of nutrients has been success-fully developed in recent years and has brought about positive results in wastewater treatment and microalgal biomass recovery while producing valuable products. This study presents the application of a microalgae and activated sludge (AS) co-culture in a low agitation photobioreactor (aPBR), which could reduce energy usage. In addition, the results demonstrate the role of settling time on co-culture flocculation progress and wastewater treatment performance. The average Chemical Oxygen Demand (COD) removal was up to 76.1% of co-culture and was achieved using a PBR system with a low agitation speed of 80 rpm. Moreover, a high biomass growth was observed to be coupled with high nutrient removal. After 63 days of operation, heavy flocs with excel-lent settling ability were dominant in the photobioreactor. This would be a preliminary step for activated algae granulation in a co-culture system.

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Yu, Byung Sun, Young Joon Sung, Min Eui Hong et Sang Jun Sim. « Improvement of Photoautotrophic Algal Biomass Production after Interrupted CO2 Supply by Urea and KH2PO4 Injection ». Energies 14, n^o 3 (2 février 2021) : 778. http://dx.doi.org/10.3390/en14030778.

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Microalgae-derived biomass is currently considered a sustainable feedstock for making biofuels, including biodiesel and direct combustion fuel. The photoautotrophic cultivation of microalgae using flue gas from power plants has been continuously investigated to improve the economic feasibility of microalgae processes. The utilization of waste CO2 from power plants is advantageous in reducing carbon footprints and the cost of carbon sources. Nonetheless, the sudden interruption of CO2 supply during microalgal cultivation leads to a severe reduction in biomass productivity. Herein, chemical fertilizers including urea and KH2PO4 were added to the culture medium when CO2 supply was halted. Urea (5 mM) and KH2PO4 (5 mM) were present in the culture medium in the form of CO2/NH4+ and K+/H2PO4−, respectively, preventing cell growth inhibition. The culture with urea and KH2PO4 supplementation exhibited 10.02-fold higher and 7.28-fold higher biomass and lipid productivity, respectively, compared to the culture with ambient CO2 supply due to the maintenance of a stable pH and dissolved inorganic carbon in the medium. In the mass cultivation of microalgae using flue gas from coal-fired power plants, urea and KH2PO4 were supplied while the flue gas supply was shut off. Consequently, the microalgae were grown successfully without cell death.

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Sarwa, Prakash, et Sanjay Kumar Verma. « Identification and Characterization of Green Microalgae, Scenedesmus sp. MCC26 and Acutodesmus obliquus MCC33 Isolated From Industrial Polluted Site Using Morphological and Molecular Markers ». International Journal of Applied Sciences and Biotechnology 5, n^o 4 (24 décembre 2017) : 415–22. http://dx.doi.org/10.3126/ijasbt.v5i4.18083.

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Two unicellular green microalgae, were isolated from Amani Shah Nallah (Jaipur, India) that receives discharge of dyeing industries. Preliminary morphological characterization using light microscopy showed ovoid, fusiform shape of cells with single to two celled coenobia in a culture suspension. Transmission electron microscopy (TEM) analyses depict abundant chloroplast located at the periphery of the cell, a pyrenoid as well as nucleus is visible in the centre. A well developed cell wall with many layers is also evident in TEM. Phylogenetic position and genetic variabilty among the isolated microalgal strains were investigated by 18S rDNA sequence analysis. The results suggest that the isolated microalgae belongs to family chlorophyceae and corresponds to genus Scenedesmus and genus Acutodesmus. Growth profile of both microalgal strains showed a typical sigmoid curve with specific growth rate of µmax, 0.839 day-1 and 0.654 day-1 for Scenedesmus sp. and Acutodesmus obliquus, respectively. The strains were allotted with MCC numbers by IARI, New Delhi as MCC26 for Scenedesmus sp. and MCC33 for Acutodesmus obliquus.Int. J. Appl. Sci. Biotechnol. Vol 5(4): 415-422

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Li, Gang, Yuhang Hao, Tenglun Yang, Wenbo Xiao, Minmin Pan, Shuhao Huo et Tao Lyu. « Enhancing Bioenergy Production from the Raw and Defatted Microalgal Biomass Using Wastewater as the Cultivation Medium ». Bioengineering 9, n^o 11 (2 novembre 2022) : 637. http://dx.doi.org/10.3390/bioengineering9110637.

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Improving the efficiency of using energy and decreasing impacts on the environment will be an inevitable choice for future development. Based on this direction, three kinds of medium (modified anaerobic digestion wastewater, anaerobic digestion wastewater and a standard growth medium BG11) were used to culture microalgae towards achieving high-quality biodiesel products. The results showed that microalgae culturing with anaerobic digestate wastewater could increase lipid content (21.8%); however, the modified anaerobic digestion wastewater can boost the microalgal biomass production to 0.78 ± 0.01 g/L when compared with (0.35–0.54 g/L) the other two groups. Besides the first step lipid extraction, the elemental composition, thermogravimetric and pyrolysis products of the defatted microalgal residues were also analysed to delve into the utilisation potential of microalgae biomass. Defatted microalgae from modified wastewater by pyrolysis at 650 °C resulted in an increase in the total content of valuable products (39.47%) with no significant difference in the content of toxic compounds compared to other groups. Moreover, the results of the life cycle assessment showed that the environmental impact (388.9 mPET2000) was lower than that of raw wastewater (418.1 mPET2000) and standard medium (497.3 mPET2000)-cultivated groups. Consequently, the method of culturing microalgae in modified wastewater and pyrolyzing algal residues has a potential to increase renewable energy production and reduce environmental impact.

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