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Sartori RB, Deprá MC, Dias RR, Fagundes MB, Zepka LQ, Jacob-Lopes E. The Role of Light on the Microalgae Biotechnology: Fundamentals, Technological Approaches, and Sustainability Issues. Recent Pat Biotechnol 2024; 18:22-51. [PMID: 38205773 DOI: 10.2174/1872208317666230504104051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/03/2023] [Accepted: 02/14/2023] [Indexed: 01/12/2024]
Abstract
Light energy directly affects microalgae growth and productivity. Microalgae in natural environments receive light through solar fluxes, and their duration and distribution are highly variable over time. Consequently, microalgae must adjust their photosynthetic processes to avoid photo limitation and photoinhibition and maximize yield. Considering these circumstances, adjusting light capture through artificial lighting in the main culture systems benefits microalgae growth and induces the production of commercially important compounds. In this sense, this review provides a comprehensive study of the role of light in microalgae biotechnology. For this, we present the main fundamentals and reactions of metabolism and metabolic alternatives to regulate photosynthetic conversion in microalgae cells. Light conversions based on natural and artificial systems are compared, mainly demonstrating the impact of solar radiation on natural systems and lighting devices, spectral compositions, periodic modulations, and light fluxes when using artificial lighting systems. The most commonly used photobioreactor design and performance are shown herein, in addition to a more detailed discussion of light-dependent approaches in these photobioreactors. In addition, we present the principal advances in photobioreactor projects, focusing on lighting, through a patent-based analysis to map technological trends. Lastly, sustainability and economic issues in commercializing microalgae products were presented.
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Affiliation(s)
- Rafaela Basso Sartori
- Bioprocess Intensification Group, Federal University of Santa Maria, Roraima Avenue, 1000, 97105-900, Santa Maria, RS, Brazil
| | - Mariany Costa Deprá
- Bioprocess Intensification Group, Federal University of Santa Maria, Roraima Avenue, 1000, 97105-900, Santa Maria, RS, Brazil
| | - Rosangela Rodrigues Dias
- Bioprocess Intensification Group, Federal University of Santa Maria, Roraima Avenue, 1000, 97105-900, Santa Maria, RS, Brazil
| | - Mariane Bittencourt Fagundes
- Bioprocess Intensification Group, Federal University of Santa Maria, Roraima Avenue, 1000, 97105-900, Santa Maria, RS, Brazil
| | - Leila Queiroz Zepka
- Bioprocess Intensification Group, Federal University of Santa Maria, Roraima Avenue, 1000, 97105-900, Santa Maria, RS, Brazil
| | - Eduardo Jacob-Lopes
- Bioprocess Intensification Group, Federal University of Santa Maria, Roraima Avenue, 1000, 97105-900, Santa Maria, RS, Brazil
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Debnath T, Bandyopadhyay TK, Vanitha K, Bobby MN, Nath Tiwari O, Bhunia B, Muthuraj M. Astaxanthin from microalgae: A review on structure, biosynthesis, production strategies and application. Food Res Int 2024; 176:113841. [PMID: 38163732 DOI: 10.1016/j.foodres.2023.113841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/27/2023] [Accepted: 12/06/2023] [Indexed: 01/03/2024]
Abstract
Astaxanthin is a red-colored secondary metabolite with excellent antioxidant properties, typically finds application as foods, feed, cosmetics, nutraceuticals, and medications. Astaxanthin is usually produced synthetically using chemicals and costs less as compared to the natural astaxanthin obtained from fish, shrimps, and microorganisms. Over the decades, astaxanthin has been naturally synthesized from Haematococcus pluvialis in commercial scales and remains exceptional, attributed to its higher bioactive properties as compared to synthetic astaxanthin. However, the production cost of algal astaxanthin is still high due to several bottlenecks prevailing in the upstream and downstream processes. To that end, the present study intends to review the recent trends and advancements in astaxanthin production from microalgae. The structure of astaxanthin, sources, production strategies of microalgal astaxanthin, and factors influencing the synthesis of microalgal astaxanthin were discussed while detailing the pathway involved in astaxanthin biosynthesis. The study also discusses the relevant downstream process used in commercial scales and details the applications of astaxanthin in various health related issues.
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Affiliation(s)
- Taniya Debnath
- Bioproducts Processing Research Laboratory (BPRL), Department of Bio Engineering, National Institute of Technology, Agartala, 799046, India
| | | | - Kondi Vanitha
- Department of Pharmaceutics, Vishnu Institute of Pharmaceutical Education and Research, Narsapur, Medak, Telangana, India
| | - Md Nazneen Bobby
- Department of Biotechnology, Vignan's Foundation for Science Technology and Research, Guntur 522213, Andhra Pradesh, India
| | - Onkar Nath Tiwari
- Centre for Conservation and Utilization of Blue Green Algae, Division of Microbiology, Indian Agricultural Research Institute (ICAR), New Delhi 110012, India.
| | - Biswanath Bhunia
- Bioproducts Processing Research Laboratory (BPRL), Department of Bio Engineering, National Institute of Technology, Agartala, 799046, India.
| | - Muthusivaramapandian Muthuraj
- Bioproducts Processing Research Laboratory (BPRL), Department of Bio Engineering, National Institute of Technology, Agartala, 799046, India; Department of Bio Engineering, National Institute of Technology, Agartala-799046, India.
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Kiehbadroudinezhad M, Hosseinzadeh-Bandbafha H, Karimi K, Madadi M, Chisti Y, Peng W, Liu D, Tabatabaei M, Aghbashlo M. Production of chemicals and utilities in-house improves the environmental sustainability of phytoplankton-based biorefinery. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 899:165751. [PMID: 37499830 DOI: 10.1016/j.scitotenv.2023.165751] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/21/2023] [Accepted: 07/22/2023] [Indexed: 07/29/2023]
Abstract
Life cycle assessment was used to evaluate the environmental impacts of phytoplanktonic biofuels as possible sustainable alternatives to fossil fuels. Three scenarios were examined for converting planktonic biomass into higher-value commodities and energy streams using the alga Scenedesmus sp. and the cyanobacterium Arthrospira sp. as the species of interest. The first scenario (Sc-1) involved the production of biodiesel and glycerol from the planktonic biomass. In the second scenario (Sc-2), biodiesel and glycerol were generated from the planktonic biomass, and biogas was produced from the residual biomass. The process also involved using a catalyst derived from snail shells for biodiesel production. The third scenario (Sc-3) was similar to Sc-2 but converted CO2 from the biogas upgrading to methanol, which was then used in synthesizing biodiesel. The results indicated that Sc-2 and Sc-3 had a reduced potential (up to 60 % less) for damaging human health compared to Sc-1. Sc-2 and Sc-3 had up to 61 % less environmental impact than Sc-1. Sc-2 and Sc-3 reduced the total cumulative exergy demand by up to 44 % compared to Sc-1. In conclusion, producing chemicals and utilities within the biorefinery could significantly improve environmental sustainability, reduce waste, and diversify revenue streams.
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Affiliation(s)
- Mohammadali Kiehbadroudinezhad
- Key Laboratory for Tobacco Gene Resources, Tobacco Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Qingdao 266101, China; Division of Engineering, Saint Mary's University, Halifax, NS B3H 3C3, Canada
| | | | - Keikhosro Karimi
- Department of Chemical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran; Department of Chemical Engineering, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Meysam Madadi
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Yusuf Chisti
- Higher Institution Centre of Excellence, Institute of Tropical Aquaculture and Fisheries, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
| | - Wanxi Peng
- Henan Province Engineering Research Center for Biomass Value-Added Products, School of Forestry, Henan Agricultural University, Zhengzhou 450002, China
| | - Dan Liu
- Key Laboratory for Tobacco Gene Resources, Tobacco Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Qingdao 266101, China.
| | - Meisam Tabatabaei
- Higher Institution Centre of Excellence, Institute of Tropical Aquaculture and Fisheries, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia; Department of Biomaterials, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Chennai 600 077, India.
| | - Mortaza Aghbashlo
- Department of Mechanical Engineering of Agricultural Machinery, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
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Conceptual Design of an Autotrophic Multi-Strain Microalgae-Based Biorefinery: Preliminary Techno-Economic and Life Cycle Assessments. FERMENTATION-BASEL 2023. [DOI: 10.3390/fermentation9030255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Microalgae represent a promising solution in addressing the impacts associated with the current agricultural and manufacturing practices which are causing irreparable environmental damage. Microalgae have considerable biosynthetic potential, being a rich source of lipids, proteins, and high-value compounds. Under the scope of the H2020-BBI MULTI-STR3AM project, an innovative large-scale production system of valuable commodities for the food, feed, and fragrance sectors is being developed on the basis of microalgae, reducing costs, increasing the scale of production, and boosting value chain sustainability. In this work, we aimed to create a process model that can mimic an industrial plant to estimate mass and energy balances, optimize scheduling, and calculate production costs for a large-scale plant. Three autotrophic microalgae strains (Nannochloropsis sp., Dunaliella sp. and Spirulina sp.) were considered for this assessment, as well as the use of locally sourced CO2 (flue gas). The developed process model is a useful tool for obtaining the data required for techno-economic analysis (TEA) and life cycle assessment (LCA) of industrial biorefinery-based processes. Nannochloropsis sp. was the most economic option, whereas Dunaliella sp. was the most expensive strain to produce due to its lower productivity. Preliminary environmental assessments of the climate change impact category revealed that water recirculation and the use of flue gas could lead to values of 5.6, 10.6, and 9.2 kgCO2eq·kgAFDW−1 for Nannochloropsis sp., Dunaliella sp., and Spirulina sp., respectively, with electricity and NaCl as the main contributors. The obtained data allow for the quantification of the production costs and environmental impacts of the microalgal biomass fractions produced, which will be fundamental for future comparison studies and in determining if they are higher or lower than those of the replaced products. The process model developed in this work provides a useful tool for the evaluation and optimization of large-scale microalgae production systems.
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Smetana S, Ristic D, Pleissner D, Tuomisto HL, Parniakov O, Heinz V. Meat substitutes: Resource demands and environmental footprints. RESOURCES, CONSERVATION, AND RECYCLING 2023; 190:106831. [PMID: 36874227 PMCID: PMC9936781 DOI: 10.1016/j.resconrec.2022.106831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 11/11/2022] [Accepted: 12/10/2022] [Indexed: 06/18/2023]
Abstract
The modern food system is characterized with high environmental impact, which is in many cases associated with increased rates of animal production and overconsumption. The adoption of alternatives to meat proteins (insects, plants, mycoprotein, microalgae, cultured meat, etc.) might potentially influence the environmental impact and human health in a positive or negative way but could also trigger indirect impacts with higher consumption rates. Current review provides a condensed analysis on potential environmental impacts, resource consumption rates and unintended trade-offs associated with integration of alternative proteins in complex global food system in the form of meat substitutes. We focus on emissions of greenhouse gases, land use, non-renewable energy use and water footprint highlighted for both ingredients used for meat substitutes and ready products. The benefits and limitations of meat substitution are highlighted in relation to a weight and protein content. The analysis of the recent research literature allowed us to define issues, that require the attention of future studies.
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Affiliation(s)
- Sergiy Smetana
- German Institute of Food Technologies (DIL e.V.), Germany
| | - Dusan Ristic
- German Institute of Food Technologies (DIL e.V.), Germany
- Institute of Food Technology, University of Natural Resources and Life Sciences (BOKU), Austria
| | - Daniel Pleissner
- Institute for Food and Environmental Research (ILU e. V.), Germany
- Institute for Sustainable Chemistry, Leuphana University Lüneburg, Germany
| | - Hanna L. Tuomisto
- Helsinki Institute of Sustainability Science (HELSUS), University of Helsinki, Finland
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Finland
- Natural Resources Institute Finland (Luke), Finland
| | | | - Volker Heinz
- German Institute of Food Technologies (DIL e.V.), Germany
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Bezerra RP, Conniff AS, Uversky VN. Comparative study of structures and functional motifs in lectins from the commercially important photosynthetic microorganisms. Biochimie 2022; 201:63-74. [PMID: 35839918 DOI: 10.1016/j.biochi.2022.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 06/17/2022] [Accepted: 07/08/2022] [Indexed: 11/26/2022]
Abstract
Photosynthetic microorganisms, specifically cyanobacteria and microalgae, can synthesize a vast array of biologically active molecules, such as lectins, that have great potential for various biotechnological and biomedical applications. However, since the structures of these proteins are not well established, likely due to the presence of intrinsically disordered regions, our ability to better understand their functionality is hampered. We embarked on a study of the carbohydrate recognition domain (CRD), intrinsically disordered regions (IDRs), amino acidic composition, as well as and functional motifs in lectins from cyanobacteria of the genus Arthrospira and microalgae Chlorella and Dunaliella genus using a combination of bioinformatics techniques. This search revealed the presence of five distinctive CRD types differently distributed between the genera. Most CRDs displayed a group-specific distribution, except to C. sorokiniana possessing distinctive CRD probably due to its specific lifestyle. We also found that all CRDs contain short IDRs. Bacterial lectin of Arthrospira prokarionte showed lower intrinsic disorder and proline content when compared to the lectins from the eukaryotic microalgae (Chlorella and Dunaliella). Among the important functions predicted in all lectins were several specific motifs, which directly interacts with proteins involved in the cell-cycle control and which may be used for pharmaceutical purposes. Since the aforementioned properties of each type of lectin were investigated in silico, they need experimental confirmation. The results of our study provide an overview of the distribution of CRD, IDRs, and functional motifs within lectin from the commercially important microalgae.
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Affiliation(s)
- Raquel P Bezerra
- Department of Morphology and Animal Physiology, Federal Rural University of Pernambuco-UFRPE, Dom Manoel de Medeiros Ave, Recife, PE, 52171-900, Brazil.
| | - Amanda S Conniff
- Department of Medical Engineering, Morsani College of Medicine and College of Engineering, University of South Florida, Tampa, FL, 33612, USA.
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA.
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Guidance for formulating ingredients/products from Chlorella vulgaris and Arthrospira platensis considering carotenoid and chlorophyll bioaccessibility and cellular uptake. Food Res Int 2022; 157:111469. [DOI: 10.1016/j.foodres.2022.111469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 05/27/2022] [Accepted: 06/02/2022] [Indexed: 11/18/2022]
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Dias RR, Deprá MC, Zepka LQ, Jacob-Lopes E. In silico study of hybrid renewable energy in microalgae facilities: A path towards net-zero emissions. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Miyashita SI, Ogura T, Kondo T, Fujii SI, Inagaki K, Takahashi Y, Minoda A. Recovery of Au from dilute aqua regia solutions via adsorption on the lyophilized cells of a unicellular red alga Galdieria sulphuraria: A mechanism study. JOURNAL OF HAZARDOUS MATERIALS 2022; 425:127982. [PMID: 34894509 DOI: 10.1016/j.jhazmat.2021.127982] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 11/28/2021] [Accepted: 12/01/2021] [Indexed: 06/14/2023]
Abstract
The high electrical conductivity, chemical stability, and low toxicity of elemental Au make it a highly valuable resource. However, wastewater produced during the mining, utilization, and disposal of Au inevitably contains small amounts (10-40 mg L-1) of Au, thus posing environmental risks. It is too acidic to be treated with inexpensive and eco-friendly bioadsorbents previously studied for the remediation of less acidic effluents. Herein, lyophilized Galdieria sulphuraria cells are shown to directly adsorb Au from simulated Au-containing wastewater with a total acid concentration of 4 M, achieving an adsorption capacity of 35 ± 2.5 mg g-1 Au after 30-min exposure and a selectivity that exceeds that of an ion-exchange resin and is comparable to that of activated carbon. Additionally, Au adsorbed on these cells is more easily eluted than that adsorbed on the ion-exchange resin or activated carbon. Detailed characterizations reveal that Au accumulates on the surface of lyophilized cells, where it is mainly present as AuCl4- and not as Au0, in contrast to a previously proposed adsorption mechanism. Thus, our work provides valuable insights into the mechanism of Au adsorption on biomaterials and paves the way to the cheap and eco-friendly recovery of Au from acidic wastewater.
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Affiliation(s)
- Shin-Ichi Miyashita
- National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan.
| | - Toshihiko Ogura
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 6, Higashi, Tsukuba, Ibaraki 305-8566, Japan.
| | - Takahiro Kondo
- Department of Materials Science and Tsukuba Research Center for Energy Materials Science, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
| | - Shin-Ichiro Fujii
- National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan.
| | - Kazumi Inagaki
- National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan.
| | - Yoshio Takahashi
- Department of Earth and Planetary Science, the University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Ayumi Minoda
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
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Severo IA, dos Santos AM, Deprá MC, Barin JS, Jacob-Lopes E. Microalgae photobioreactors integrated into combustion processes: A patent-based analysis to map technological trends. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Thielemann AK, Smetana S, Pleissner D. Cultivation of the heterotrophic microalga Galdieria sulphuraria on food waste: A Life Cycle Assessment. BIORESOURCE TECHNOLOGY 2021; 340:125637. [PMID: 34315124 DOI: 10.1016/j.biortech.2021.125637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/11/2021] [Accepted: 07/18/2021] [Indexed: 06/13/2023]
Abstract
The aim of this study was to perform a Life Cycle Assessment of a production process of 1 kg dry algal biomass powder (Galdieria sulphuraria) with 27 % (w/w) protein content for human consumption for optimizing the production regarding global warming potential and resource efficiency in combination with food waste utilization. It was investigated, underpinned by a comparison of the use of conventional glucose, whether and to what extent the environmental impact/global warming potential can be reduced by changing to food waste hydrolysate and how this can lead to a more sustainable use of resources and a sustainable development. Overall, the results showed that hydrolysis, along with freeze-drying, caused most of the overall impact. The carbon footprint associated with the use of hydrolyzed food waste was 11% higher than using conventional glucose and supplementary nutrients mainly driven by the high demand of energy for hydrolysis.
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Affiliation(s)
- Anne Karolin Thielemann
- Sustainable Chemistry (Resource Efficiency), Institute of Sustainable Chemistry, Leuphana University of Lüneburg, Universitätsallee 1, Lüneburg C13.203, 21335, Germany; Institute for Food and Environmental Research e. V., Papendorfer Weg 3, Bad Belzig 14806, Germany
| | - Sergiy Smetana
- German Institute of Food Technologies - DIL e.V., Prof.-von-Klitzing-Str. 7, Quakenbrück 49610, Germany
| | - Daniel Pleissner
- Sustainable Chemistry (Resource Efficiency), Institute of Sustainable Chemistry, Leuphana University of Lüneburg, Universitätsallee 1, Lüneburg C13.203, 21335, Germany; Institute for Food and Environmental Research e. V., Papendorfer Weg 3, Bad Belzig 14806, Germany.
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Comparative Life Cycle Assessment of EPA and DHA Production from Microalgae and Farmed Fish. CLEAN TECHNOLOGIES 2021. [DOI: 10.3390/cleantechnol3040042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The present study aims at comparing the life cycle environmental impacts of polyunsaturated fatty acids production (PUFA) from microalgae and farmed fish. PUFA production from microalgae cultivated via heterotrophy and photoautotrophy was assessed and compared. The primary energy demand (PED) and environmental impacts (EI) of PUFA production from microalgae via heterotrophy were significantly lower compared to PUFA produced via photoautotrophy. Furthermore, PED and EI of PUFA production from fish farmed in marine net pens were assessed. The results indicated that the PED and EI of PUFA production from farmed fish are higher than that produced from microalgae cultivated via heterotrophy. Therefore, the results suggest that PUFA produced from microalgae via heterotrophy could substitute fish oil from an environmental perspective. Furthermore, life cycle analysis results indicate that PUFA derived from microalgae could potentially replace fish oil in the fish feed, thus reducing the pressure on oceans.
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Insights into the physiology of Chlorella vulgaris cultivated in sweet sorghum bagasse hydrolysate for sustainable algal biomass and lipid production. Sci Rep 2021; 11:6779. [PMID: 33762646 PMCID: PMC7991646 DOI: 10.1038/s41598-021-86372-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/15/2021] [Indexed: 02/06/2023] Open
Abstract
Supplementing cultivation media with exogenous carbon sources enhances biomass and lipid production in microalgae. Utilization of renewable organic carbon from agricultural residues can potentially reduce the cost of algae cultivation, while enhancing sustainability. In the present investigation a medium was developed from sweet sorghum bagasse for cultivation of Chlorella under mixotrophic conditions. Using response surface methodology, the optimal values of critical process parameters were determined, namely inoculum cell density (O.D.750) of 0.786, SSB hydrolysate content of the medium 25% v/v, and zero medium salinity, to achieve maximum lipid productivity of 120 mg/L/d. Enhanced biomass (3.44 g/L) and lipid content (40% of dry cell weight) were observed when the alga was cultivated in SSB hydrolysate under mixotrophic conditions compared to heterotrophic and photoautotrophic conditions. A time course investigation revealed distinct physiological responses in terms of cellular growth and biochemical composition of C. vulgaris cultivated in the various trophic modes. The determined carbohydrate and lipid profiles indicate that sugar addition to the cultivation medium boosts neutral lipid synthesis compared to structural lipids, suggesting that carbon flux is channeled towards triacylglycerol synthesis in the cells. Furthermore, the fatty acid profile of lipids extracted from mixotrophically grown cultures contained more saturated and monosaturated fatty acids, which are suitable for biofuel manufacturing. Scale-up studies in a photobioreactor using SSB hydrolysate achieved a biomass concentration of 2.83 g/L consisting of 34% lipids and 26% carbohydrates. These results confirmed that SSB hydrolysate is a promising feedstock for mixotrophic cultivation of Chlorella and synthesis of algal bioproducts and biofuels.
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