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Venkata Subhash G, Rajvanshi M, Raja Krishna Kumar G, Shankar Sagaram U, Prasad V, Govindachary S, Dasgupta S. Challenges in microalgal biofuel production: A perspective on techno economic feasibility under biorefinery stratagem. BIORESOURCE TECHNOLOGY 2022; 343:126155. [PMID: 34673195 DOI: 10.1016/j.biortech.2021.126155] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 06/13/2023]
Abstract
Rapidly exhausting fossil fuels combined with the ever-increasing demand for energy led to an ongoing search for alternative energy sources to meet the transportation, manufacturing, domestic and other energy demands of the grown population. Microalgae are at the forefront of alternative energy research due to their significant potential as a renewable feedstock for biofuels. However, microalgae platforms have not found a way into industrial-scale bioenergy production due to various technical and economic constraints. The present review provides a detailed overview of the challenges in microalgae production processes for bioenergy purposes with supporting techno-economic assessments related to microalgae cultivation, harvesting and downstream processes required for crude oil or biofuel production. In addition, biorefinery approaches that can valorize the by-products or co-products in microalgae production and enhance the techno-economics of the production process are discussed.
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Affiliation(s)
- G Venkata Subhash
- Reliance Research and Development Centre, Reliance Corporate Park, Thane-Belapur Road, NaviMumbai 400701, India.
| | - Meghna Rajvanshi
- Reliance Research and Development Centre, Reliance Corporate Park, Thane-Belapur Road, NaviMumbai 400701, India
| | - G Raja Krishna Kumar
- Reliance Research and Development Centre, Reliance Corporate Park, Thane-Belapur Road, NaviMumbai 400701, India
| | - Uma Shankar Sagaram
- Reliance Research and Development Centre, Reliance Corporate Park, Thane-Belapur Road, NaviMumbai 400701, India
| | - Venkatesh Prasad
- Reliance Research and Development Centre, Reliance Corporate Park, Thane-Belapur Road, NaviMumbai 400701, India
| | - Sridharan Govindachary
- Reliance Research and Development Centre, Reliance Corporate Park, Thane-Belapur Road, NaviMumbai 400701, India
| | - Santanu Dasgupta
- Reliance Research and Development Centre, Reliance Corporate Park, Thane-Belapur Road, NaviMumbai 400701, India
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Sarma S, Sharma S, Rudakiya D, Upadhyay J, Rathod V, Patel A, Narra M. Valorization of microalgae biomass into bioproducts promoting circular bioeconomy: a holistic approach of bioremediation and biorefinery. 3 Biotech 2021; 11:378. [PMID: 34367870 DOI: 10.1007/s13205-021-02911-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/28/2021] [Indexed: 11/30/2022] Open
Abstract
The need for alternative source of fuel has demanded the cultivation of 3rd generation feedstock which includes microalgae, seaweed and cyanobacteria. These phototrophic organisms are unique in a sense that they utilise natural sources like sunlight, water and CO2 for their growth and metabolism thereby producing diverse products that can be processed to produce biofuel, biochemical, nutraceuticals, feed, biofertilizer and other value added products. But due to low biomass productivity and high harvesting cost, microalgae-based production have not received much attention. Therefore, this review provides the state of the art of the microalgae based biorefinery approach to define an economical and sustainable process. The three major segments that need to be considered for economic microalgae biorefinery is low cost nutrient source, efficient harvesting methods and production of by-products with high market value. This review has outlined the use of various wastewater as nutrient source for simultaneous biomass production and bioremediation. Further, it has highlighted the common harvesting methods used for microalgae and also described various products from both raw biomass and delipidified microalgae residues in order to establish a sustainable, economical microalgae biorefinery with a touch of circular bioeconomy. This review has also discussed various challenges to be considered followed by a techno-economic analysis of the microalgae based biorefinery model.
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Affiliation(s)
- Shyamali Sarma
- Bioconversion Technology Division, Sardar Patel Renewable Energy Research Institute, Vallabh Vidyanagar, Post Box No. 2, Anand, Gujarat 388120 India
| | - Shaishav Sharma
- Bioconversion Technology Division, Sardar Patel Renewable Energy Research Institute, Vallabh Vidyanagar, Post Box No. 2, Anand, Gujarat 388120 India
| | - Darshan Rudakiya
- Bioconversion Technology Division, Sardar Patel Renewable Energy Research Institute, Vallabh Vidyanagar, Post Box No. 2, Anand, Gujarat 388120 India
| | - Jinal Upadhyay
- Bioconversion Technology Division, Sardar Patel Renewable Energy Research Institute, Vallabh Vidyanagar, Post Box No. 2, Anand, Gujarat 388120 India
| | - Vinod Rathod
- Bioconversion Technology Division, Sardar Patel Renewable Energy Research Institute, Vallabh Vidyanagar, Post Box No. 2, Anand, Gujarat 388120 India
| | - Aesha Patel
- Bioconversion Technology Division, Sardar Patel Renewable Energy Research Institute, Vallabh Vidyanagar, Post Box No. 2, Anand, Gujarat 388120 India
| | - Madhuri Narra
- Bioconversion Technology Division, Sardar Patel Renewable Energy Research Institute, Vallabh Vidyanagar, Post Box No. 2, Anand, Gujarat 388120 India
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Mavrommati M, Daskalaki A, Papanikolaou S, Aggelis G. Adaptive laboratory evolution principles and applications in industrial biotechnology. Biotechnol Adv 2021; 54:107795. [PMID: 34246744 DOI: 10.1016/j.biotechadv.2021.107795] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/11/2021] [Accepted: 07/05/2021] [Indexed: 12/20/2022]
Abstract
Adaptive laboratory evolution (ALE) is an innovative approach for the generation of evolved microbial strains with desired characteristics, by implementing the rules of natural selection as presented in the Darwinian Theory, on the laboratory bench. New as it might be, it has already been used by several researchers for the amelioration of a variety of characteristics of widely used microorganisms in biotechnology. ALE is used as a tool for the deeper understanding of the genetic and/or metabolic pathways of evolution. Another important field targeted by ALE is the manufacturing of products of (high) added value, such as ethanol, butanol and lipids. In the current review, we discuss the basic principles and techniques of ALE, and then we focus on studies where it has been applied to bacteria, fungi and microalgae, aiming to improve their performance to biotechnological procedures and/or inspect the genetic background of evolution. We conclude that ALE is a promising and efficacious method that has already led to the acquisition of useful new microbiological strains in biotechnology and could possibly offer even more interesting results in the future.
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Affiliation(s)
- Maria Mavrommati
- Unit of Microbiology, Department of Biology, Division of Genetics, Cell Biology and Development, University of Patras, 26504 Patras, Greece; Laboratory of Food Microbiology and Biotechnology, Department of Food Science and Human Nutrition, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece
| | - Alexandra Daskalaki
- Unit of Microbiology, Department of Biology, Division of Genetics, Cell Biology and Development, University of Patras, 26504 Patras, Greece
| | - Seraphim Papanikolaou
- Laboratory of Food Microbiology and Biotechnology, Department of Food Science and Human Nutrition, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece
| | - George Aggelis
- Unit of Microbiology, Department of Biology, Division of Genetics, Cell Biology and Development, University of Patras, 26504 Patras, Greece.
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Biosynthesis of Polyhydroxyalkanoates from Defatted Chlorella Biomass as an Inexpensive Substrate. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11031094] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Microalgae biomass has been recently used as an inexpensive substrate for the industrial production of polyhydroxyalkanoates (PHAs). In this work, a dilute acid pretreatment using 0.3 N of hydrochloric acid (HCl) was performed to extract reducing sugars from 10% (w/v) of defatted Chlorella biomass (DCB). The resulting HCl DCB hydrolysate was used as a renewable substrate to assess the ability of three bacterial strains, namely Bacillus megaterium ALA2, Cupriavidus necator KCTC 2649, and Haloferax mediterranei DSM 1411, to produce PHA in shake flasks. The results show that under 20 g/L of DCB hydrolysate derived sugar supplementation, the cultivated strains successfully accumulated PHA up to 29.7–75.4% of their dry cell weight (DCW). Among the cultivated strains, C. necator KCTC 2649 exhibited the highest PHA production (7.51 ± 0.20 g/L, 75.4% of DCW) followed by H. mediterranei DSM 1411 and B. megaterium ALA2, for which a PHA content of 3.79 ± 0.03 g/L (55.5% of DCW) and 0.84 ± 0.06 g/L (29.7% of DCW) was recorded, respectively. Along with PHA, a maximum carotenoid content of 1.80 ± 0.16 mg/L was produced by H. mediterranei DSM 1411 at 120 h of cultivation in shake flasks. PHA and carotenoid production increased by 1.45- and 1.37-fold, respectively, when HCl DCB hydrolysate biotransformation was upscaled to a 1 L of working volume fermenter. Based on FTIR and 1H NMR analysis, PHA polymers accumulated by B. megaterium ALA2 and C. necator KCTC 2649 were identified as homopolymers of poly(3-hydroxybutyrate). However, a copolymer of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with a 3-hydroxyvalerate fraction of 10.5 mol% was accumulated by H. mediterranei DSM 1411.
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Ma R, Wang B, Chua ET, Zhao X, Lu K, Ho SH, Shi X, Liu L, Xie Y, Lu Y, Chen J. Comprehensive Utilization of Marine Microalgae for Enhanced Co-Production of Multiple Compounds. Mar Drugs 2020; 18:md18090467. [PMID: 32948074 PMCID: PMC7551828 DOI: 10.3390/md18090467] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 09/11/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022] Open
Abstract
Marine microalgae are regarded as potential feedstock because of their multiple valuable compounds, including lipids, pigments, carbohydrates, and proteins. Some of these compounds exhibit attractive bioactivities, such as carotenoids, ω-3 polyunsaturated fatty acids, polysaccharides, and peptides. However, the production cost of bioactive compounds is quite high, due to the low contents in marine microalgae. Comprehensive utilization of marine microalgae for multiple compounds production instead of the sole product can be an efficient way to increase the economic feasibility of bioactive compounds production and improve the production efficiency. This paper discusses the metabolic network of marine microalgal compounds, and indicates their interaction in biosynthesis pathways. Furthermore, potential applications of co-production of multiple compounds under various cultivation conditions by shifting metabolic flux are discussed, and cultivation strategies based on environmental and/or nutrient conditions are proposed to improve the co-production. Moreover, biorefinery techniques for the integral use of microalgal biomass are summarized. These techniques include the co-extraction of multiple bioactive compounds from marine microalgae by conventional methods, super/subcritical fluids, and ionic liquids, as well as direct utilization and biochemical or thermochemical conversion of microalgal residues. Overall, this review sheds light on the potential of the comprehensive utilization of marine microalgae for improving bioeconomy in practical industrial application.
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Affiliation(s)
- Ruijuan Ma
- Technical Innovation Service Platform for High Value and High Quality Utilization of Marine Organism, Fuzhou University, Fuzhou 350108, China; (R.M.); (K.L.); (S.-H.H.); (X.S.); (L.L.)
- Fujian Engineering and Technology Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fuzhou 350108, China
- Fuzhou Industrial Technology Innovation Center for High Value Utilization of Marine Products, Fuzhou University, Fuzhou 350108, China
| | - Baobei Wang
- College of Oceanology and Food Science, Quanzhou Normal University, Quanzhou 362000, China;
| | - Elvis T. Chua
- Algae Biotechnology Laboratory, School of Agriculture and Food Sciences, The University of Queensland, Brisbane, QLD 4072, Australia;
| | - Xurui Zhao
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; (X.Z.); (Y.L.)
| | - Kongyong Lu
- Technical Innovation Service Platform for High Value and High Quality Utilization of Marine Organism, Fuzhou University, Fuzhou 350108, China; (R.M.); (K.L.); (S.-H.H.); (X.S.); (L.L.)
- Fujian Engineering and Technology Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fuzhou 350108, China
- Fuzhou Industrial Technology Innovation Center for High Value Utilization of Marine Products, Fuzhou University, Fuzhou 350108, China
| | - Shih-Hsin Ho
- Technical Innovation Service Platform for High Value and High Quality Utilization of Marine Organism, Fuzhou University, Fuzhou 350108, China; (R.M.); (K.L.); (S.-H.H.); (X.S.); (L.L.)
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Xinguo Shi
- Technical Innovation Service Platform for High Value and High Quality Utilization of Marine Organism, Fuzhou University, Fuzhou 350108, China; (R.M.); (K.L.); (S.-H.H.); (X.S.); (L.L.)
- Fujian Engineering and Technology Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fuzhou 350108, China
- Fuzhou Industrial Technology Innovation Center for High Value Utilization of Marine Products, Fuzhou University, Fuzhou 350108, China
| | - Lemian Liu
- Technical Innovation Service Platform for High Value and High Quality Utilization of Marine Organism, Fuzhou University, Fuzhou 350108, China; (R.M.); (K.L.); (S.-H.H.); (X.S.); (L.L.)
- Fujian Engineering and Technology Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fuzhou 350108, China
- Fuzhou Industrial Technology Innovation Center for High Value Utilization of Marine Products, Fuzhou University, Fuzhou 350108, China
| | - Youping Xie
- Technical Innovation Service Platform for High Value and High Quality Utilization of Marine Organism, Fuzhou University, Fuzhou 350108, China; (R.M.); (K.L.); (S.-H.H.); (X.S.); (L.L.)
- Fujian Engineering and Technology Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fuzhou 350108, China
- Fuzhou Industrial Technology Innovation Center for High Value Utilization of Marine Products, Fuzhou University, Fuzhou 350108, China
- Correspondence: (Y.X.); (J.C.); Tel.: +86-591-22866373 (Y.X. & J.C.)
| | - Yinghua Lu
- Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; (X.Z.); (Y.L.)
| | - Jianfeng Chen
- Technical Innovation Service Platform for High Value and High Quality Utilization of Marine Organism, Fuzhou University, Fuzhou 350108, China; (R.M.); (K.L.); (S.-H.H.); (X.S.); (L.L.)
- Fujian Engineering and Technology Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fuzhou 350108, China
- Fuzhou Industrial Technology Innovation Center for High Value Utilization of Marine Products, Fuzhou University, Fuzhou 350108, China
- Correspondence: (Y.X.); (J.C.); Tel.: +86-591-22866373 (Y.X. & J.C.)
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Technical and Economic Analysis of Conventional and Supercritical Transesterification for Biofuel Production. Chem Eng Technol 2020. [DOI: 10.1002/ceat.202000058] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Ma R, Zhao X, Ho SH, Shi X, Liu L, Xie Y, Chen J, Lu Y. Co-production of lutein and fatty acid in microalga Chlamydomonas sp. JSC4 in response to different temperatures with gene expression profiles. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.101821] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Lee H, Liao JD, Yang JW, Hsu WD, Liu BH, Chen TC, Sivashanmugan K, Gedanken A. Continuous Waste Cooking Oil Transesterification with Microwave Heating and Strontium Oxide Catalyst. Chem Eng Technol 2017. [DOI: 10.1002/ceat.201600561] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Han Lee
- National Cheng Kung University; Department of Materials Science and Engineering; 1 University Road 70101 Tainan Taiwan
| | - Jiunn-Der Liao
- National Cheng Kung University; Department of Materials Science and Engineering; 1 University Road 70101 Tainan Taiwan
| | - Jung-Wei Yang
- National Cheng Kung University; Department of Materials Science and Engineering; 1 University Road 70101 Tainan Taiwan
| | - Wen-Dung Hsu
- National Cheng Kung University; Department of Materials Science and Engineering; 1 University Road 70101 Tainan Taiwan
| | - Bernard Haochih Liu
- National Cheng Kung University; Department of Materials Science and Engineering; 1 University Road 70101 Tainan Taiwan
| | - Teng-Chien Chen
- National Cheng Kung University; Department of Materials Science and Engineering; 1 University Road 70101 Tainan Taiwan
| | - Kundan Sivashanmugan
- National Cheng Kung University; Department of Materials Science and Engineering; 1 University Road 70101 Tainan Taiwan
| | - Aharon Gedanken
- National Cheng Kung University; Department of Materials Science and Engineering; 1 University Road 70101 Tainan Taiwan
- Bar-Ilan University; Department of Chemistry; 29 Nitzana Street 53465 Givatayim Israel
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Rai V, Muthuraj M, Gandhi MN, Das D, Srivastava S. Real-time iTRAQ-based proteome profiling revealed the central metabolism involved in nitrogen starvation induced lipid accumulation in microalgae. Sci Rep 2017; 7:45732. [PMID: 28378827 PMCID: PMC5381106 DOI: 10.1038/srep45732] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 03/06/2017] [Indexed: 02/06/2023] Open
Abstract
To understand the post-transcriptional molecular mechanisms attributing to oleaginousness in microalgae challenged with nitrogen starvation (N-starvation), the longitudinal proteome dynamics of Chlorella sp. FC2 IITG was investigated using multipronged quantitative proteomics and multiple reaction monitoring assays. Physiological data suggested a remarkably enhanced lipid accumulation with concomitant reduction in carbon flux towards carbohydrate, protein and chlorophyll biosynthesis. The proteomics-based investigations identified the down-regulation of enzymes involved in chlorophyll biosynthesis (porphobilinogen deaminase) and photosynthetic carbon fixation (sedoheptulose-1,7 bisphosphate and phosphoribulokinase). Profound up-regulation of hydroxyacyl-ACP dehydrogenase and enoyl-ACP reductase ascertained lipid accumulation. The carbon skeletons to be integrated into lipid precursors were regenerated by glycolysis, β-oxidation and TCA cycle. The enhanced expression of glycolysis and pentose phosphate pathway enzymes indicates heightened energy needs of FC2 cells for the sustenance of N-starvation. FC2 cells strategically reserved nitrogen by incorporating it into the TCA-cycle intermediates to form amino acids; particularly the enzymes involved in the biosynthesis of glutamate, aspartate and arginine were up-regulated. Regulation of arginine, superoxide dismutase, thioredoxin-peroxiredoxin, lipocalin, serine-hydroxymethyltransferase, cysteine synthase, and octanoyltransferase play a critical role in maintaining cellular homeostasis during N-starvation. These findings may provide a rationale for genetic engineering of microalgae, which may enable synchronized biomass and lipid synthesis.
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Affiliation(s)
- Vineeta Rai
- Department of Biosciences and Bioengineering, Wadhwani Research Center for Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, Maharashtra, India
| | - Muthusivaramapandian Muthuraj
- Department of Biosciences and Bioengineering, Centre for Energy, Indian Institute of Technology Guwahati, Assam 781039, India
| | - Mayuri N. Gandhi
- Centre for Research in Nanotechnology & Science, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Debasish Das
- Department of Biosciences and Bioengineering, Centre for Energy, Indian Institute of Technology Guwahati, Assam 781039, India
- DBT PAN IIT Centre for Bioenergy, Indian Institute of Technology Bombay, Mumbai, Powai - 400067, India
| | - Sanjeeva Srivastava
- Department of Biosciences and Bioengineering, Wadhwani Research Center for Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, Maharashtra, India
- DBT PAN IIT Centre for Bioenergy, Indian Institute of Technology Bombay, Mumbai, Powai - 400067, India
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Carotenoids from microalgae: A review of recent developments. Biotechnol Adv 2016; 34:1396-1412. [DOI: 10.1016/j.biotechadv.2016.10.005] [Citation(s) in RCA: 369] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 10/25/2016] [Accepted: 10/31/2016] [Indexed: 01/18/2023]
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Dineshkumar R, Dash SK, Sen R. Process integration for microalgal lutein and biodiesel production with concomitant flue gas CO2 sequestration: a biorefinery model for healthcare, energy and environment. RSC Adv 2015. [DOI: 10.1039/c5ra09306f] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
An integrated green microalgal biorefinery was developed with a view to sequestering flue gas CO2 and synthesizing lutein and lipid for potential environmental, healthcare and biofuel applications respectively.
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Affiliation(s)
- R. Dineshkumar
- Department of Biotechnology
- Indian Institute of Technology Kharagpur
- India
| | - Sukanta Kumar Dash
- Department of Mechanical Engineering
- Indian Institute of Technology Kharagpur
- India
| | - Ramkrishna Sen
- Department of Biotechnology
- Indian Institute of Technology Kharagpur
- India
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Guccione A, Biondi N, Sampietro G, Rodolfi L, Bassi N, Tredici MR. Chlorella for protein and biofuels: from strain selection to outdoor cultivation in a Green Wall Panel photobioreactor. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:84. [PMID: 24932216 PMCID: PMC4057815 DOI: 10.1186/1754-6834-7-84] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 05/06/2014] [Indexed: 05/03/2023]
Abstract
BACKGROUND Chlorella is one of the few microalgae employed for human consumption. It typically has a high protein content, but it can also accumulate high amounts of lipids or carbohydrates under stress conditions and, for this reason, it is of interest in the production of biofuels. High production costs and energy consumption are associated with its cultivation. This work describes a strategy to reduce costs and environmental impact of Chlorella biomass production for food, biofuels and other applications. RESULTS The growth of four Chlorella strains, selected after a laboratory screening, was investigated outdoors in a low-cost 0.25 m(2) GWP-II photobioreactor. The capacity of the selected strains to grow at high temperature was tested. On the basis of these results, in the nitrogen starvation trials the culture was cooled only when the temperature exceeded 40°C to allow for significant energy savings, and performed in a seawater-based medium to reduce the freshwater footprint. Under nutrient sufficiency, strain CH2 was the most productive. In all the strains, nitrogen starvation strongly reduced productivity, depressed protein and induced accumulation of carbohydrate (about 50%) in strains F&M-M49 and IAM C-212, and lipid (40 - 45%) in strains PROD1 and CH2. Starved cultures achieved high storage product productivities: 0.12 g L(-1) d(-1) of lipids for CH2 and 0.19 g L(-1) d(-1) of carbohydrates for F&M-M49. When extrapolated to large-scale in central Italy, CH2 showed a potential productivity of 41 t ha(-1) y(-1) for biomass, 16 t ha(-1) y(-1) for protein and 11 t ha(-1) y(-1) for lipid under nutrient sufficiency, and 8 t ha(-1) y(-1) for lipid under nitrogen starvation. CONCLUSIONS The environmental and economic sustainability of Chlorella production was enhanced by growing the organisms in a seawater-based medium, so as not to compete with crops for freshwater, and at high temperatures, so as to reduce energy consumption for cooling. All the four selected strains are good candidates for food or biofuels production in lands unsuitable for conventional agriculture. Chlorella strain CH2 has the potential for more than 80 tonnes of biomass, 32 tonnes of protein and 22 tonnes of lipid per year under favourable climates.
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Affiliation(s)
- Alessia Guccione
- Dipartimento di Scienze delle Produzioni Agroalimentari e dell’Ambiente - Sezione di Microbiologia Agraria, Università degli Studi di Firenze, Piazzale delle Cascine 24, Firenze 50144, Italy
| | - Natascia Biondi
- Dipartimento di Scienze delle Produzioni Agroalimentari e dell’Ambiente - Sezione di Microbiologia Agraria, Università degli Studi di Firenze, Piazzale delle Cascine 24, Firenze 50144, Italy
| | - Giacomo Sampietro
- Dipartimento di Scienze delle Produzioni Agroalimentari e dell’Ambiente - Sezione di Microbiologia Agraria, Università degli Studi di Firenze, Piazzale delle Cascine 24, Firenze 50144, Italy
| | - Liliana Rodolfi
- Dipartimento di Scienze delle Produzioni Agroalimentari e dell’Ambiente - Sezione di Microbiologia Agraria, Università degli Studi di Firenze, Piazzale delle Cascine 24, Firenze 50144, Italy
- Fotosintetica & Microbiologica S.r.l., Via dei Della Robbia 54, Firenze 50132, Italy
| | - Niccolò Bassi
- Fotosintetica & Microbiologica S.r.l., Via dei Della Robbia 54, Firenze 50132, Italy
| | - Mario R Tredici
- Dipartimento di Scienze delle Produzioni Agroalimentari e dell’Ambiente - Sezione di Microbiologia Agraria, Università degli Studi di Firenze, Piazzale delle Cascine 24, Firenze 50144, Italy
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