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Ashour M, Mansour AT, Alkhamis YA, Elshobary M. Usage of Chlorella and diverse microalgae for CO 2 capture - towards a bioenergy revolution. Front Bioeng Biotechnol 2024; 12:1387519. [PMID: 39229458 PMCID: PMC11368733 DOI: 10.3389/fbioe.2024.1387519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 08/05/2024] [Indexed: 09/05/2024] Open
Abstract
To address climate change threats to ecosystems and the global economy, sustainable solutions for reducing atmospheric carbon dioxide (CO2) levels are crucial. Existing CO2 capture projects face challenges like high costs and environmental risks. This review explores leveraging microalgae, specifically the Chlorella genus, for CO2 capture and conversion into valuable bioenergy products like biohydrogen. The introduction section provides an overview of carbon pathways in microalgal cells and their role in CO2 capture for biomass production. It discusses current carbon credit industries and projects, highlighting the Chlorella genus's carbon concentration mechanism (CCM) model for efficient CO2 sequestration. Factors influencing microalgal CO2 sequestration are examined, including pretreatment, pH, temperature, irradiation, nutrients, dissolved oxygen, and sources and concentrations of CO2. The review explores microalgae as a feedstock for various bioenergy applications like biodiesel, biooil, bioethanol, biogas and biohydrogen production. Strategies for optimizing biohydrogen yield from Chlorella are highlighted. Outlining the possibilities of further optimizations the review concludes by suggesting that microalgae and Chlorella-based CO2 capture is promising and offers contributions to achieve global climate goals.
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Affiliation(s)
- Mohamed Ashour
- National Institute of Oceanography and Fisheries (NIOF), Cairo, Egypt
| | - Abdallah Tageldein Mansour
- Animal and Fish Production Department, College of Agricultural and Food Sciences, King Faisal University, Al-Ahsa, Saudi Arabia
- Department of Fish and Animal Production, Faculty of Agriculture (Saba Basha), Alexandria University, Alexandria, Egypt
| | - Yousef A. Alkhamis
- Animal and Fish Production Department, College of Agricultural and Food Sciences, King Faisal University, Al-Ahsa, Saudi Arabia
- Water and Environment Study Center, King Faisal University, Al-Ahsa, Saudi Arabia
| | - Mostafa Elshobary
- Department of Botany and microbiology, Faculty of Science, Tanta University, Tanta, Egypt
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Chauhan DS, Mohanty K. Exploring microalgal nutrient-light synergy to enhance CO 2 utilization and lipid productivity in sustainable long-term water recycling cultivation. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 356:120631. [PMID: 38522275 DOI: 10.1016/j.jenvman.2024.120631] [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: 10/13/2023] [Revised: 02/01/2024] [Accepted: 03/10/2024] [Indexed: 03/26/2024]
Abstract
In this work the effects of nutrient availability and light conditions on CO2 utilization and lipid production in Micractinium pusillum KMC8 is reported. The study investigated the ideal nitrogen concentrations for growth and nitrogen utilization in a 15% CO2 environment. Logistic and Gompertz models were employed to analyze the kinetics of KMC8 cell growth. Compared to 17.6 mmol L-1 control nitrogen, which generated 1.6 g L-1 growth, doubling and quadrupling nitrogen concentrations boosted biomass growth by 12.5% and 28.78%. At 8.6 mmol L-1 nitrogen, the growth decreased but lipid productivity increased to 18.62 mg L-1 day-1. At 70.6 mmol L-1 nitrogen, elevated nitrogen levels maintained an alkaline pH above 7 and enhanced CO2 mitigation, achieving 2.27% CO2 utilization efficiency. Nitrogen shows a positive correlation with higher rates of carbon and nitrogen fixation. The investigation extends to find out the influence of phosphorus and light conditions on microalgae. Increasing light intensity incrementally from 150 to 1200 μmol m-2 s-1 with more phosphorus increased biomass productivity by 85% (255 mg L-1 day-1) and lipid productivity by 2.5-fold (84.76 mg L-1 day-1), with 3.3% CO2 utilization efficiency compared to directly using 1200 μmol m-2 s-1. This study suggests a water recycling-fed batch cycle with gradual light feeding, which results in high CO2 fixation (1.1 g L-1 day-1), 7% CO2 utilization, and significant biomass and lipid productivity (577.23 and 150 mg L-1 day-1). This approach promotes lipid synthesis, maintains carbon fixation, and minimizes biomass loss, thus supporting sustainable bioenergy development in a circular bio-economy framework.
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Affiliation(s)
- Deepesh Singh Chauhan
- School of Energy Science and Engineering, Indian Institute of Technology Guwahati, Guwahati, 781039, India
| | - Kaustubha Mohanty
- School of Energy Science and Engineering, Indian Institute of Technology Guwahati, Guwahati, 781039, India; Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, 781039, India.
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Cho JM, Oh YK, Lee J, Chang YK, Park WK. Development of dual strain microalgae cultivation system for the direct carbon dioxide utilization of power plant flue gas. BIORESOURCE TECHNOLOGY 2024; 393:130051. [PMID: 37995873 DOI: 10.1016/j.biortech.2023.130051] [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: 10/08/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 11/25/2023]
Abstract
This study aims to propose a biological system that allows for direct utilization of flue gas for carbon dioxide capture and utilization by microalgae. The strain Chlorella sp. ABC-001 is employed for its high growth rate as well as lipid and carbohydrate content. Toxicity tests showed that cell growth was unaffected by NO, but the presence of SO2 showed critical damage on cell growth. Hence, an extremophile alga, Galdieria sulphuraria 5587.1 was applied to build a dual-strain cultivation system to mitigate the effect of SO2 toxicity and increase CO2 capture efficiency. All SO2 was removed by Galdieria culture and the system exhibited stable growth from a simulated flue gas stream containing CO2, NO and SO2. Combined CO2 biofixation rate of 793 mg/L/d and lipid productivity of 113 mg/L/d was achieved. The results showed that this new cultivation system is a promising alternative for reducing CO2 emissions from power plants.
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Affiliation(s)
- Jun Muk Cho
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - You-Kwan Oh
- School of Chemical & Biomolecular Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Jiye Lee
- Gwangju Bio/Energy R&D Center, Korea Institute of Energy Research, Gwangju 61003, Republic of Korea
| | - Yong Keun Chang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea; Advanced Biomass R&D Center, Daejeon 34141, Republic of Korea
| | - Won-Kun Park
- Department of Biological Engineering, Konkuk University, Seoul 05029, Republic of Korea.
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Koh HG, Cho JM, Jeon S, Chang YK, Lee B, Kang NK. Transcriptional insights into Chlorella sp. ABC-001: a comparative study of carbon fixation and lipid synthesis under different CO 2 conditions. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:113. [PMID: 37454088 PMCID: PMC10350272 DOI: 10.1186/s13068-023-02358-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/11/2023] [Indexed: 07/18/2023]
Abstract
BACKGROUND Microalgae's low tolerance to high CO2 concentrations presents a significant challenge for its industrial application, especially when considering the utilization of industrial exhaust gas streams with high CO2 content-an economically and environmentally attractive option. Therefore, the objectives of this study were to investigate the metabolic changes in carbon fixation and lipid accumulation of microalgae under ambient air and high CO2 conditions, deepen our understanding of the molecular mechanisms driving these processes, and identify potential target genes for metabolic engineering in microalgae. To accomplish these goals, we conducted a transcriptomic analysis of the high CO2-tolerant strain, Chlorella sp. ABC-001, under two different carbon dioxide levels (ambient air and 10% CO2) and at various growth phases. RESULTS Cells cultivated with 10% CO2 exhibited significantly better growth and lipid accumulation rates, achieving up to 2.5-fold higher cell density and twice the lipid content by day 7. To understand the relationship between CO2 concentrations and phenotypes, transcriptomic analysis was conducted across different CO2 conditions and growth phases. According to the analysis of differentially expressed genes and gene ontology, Chlorella sp. ABC-001 exhibited the development of chloroplast organelles during the early exponential phase under high CO2 conditions, resulting in improved CO2 fixation and enhanced photosynthesis. Cobalamin-independent methionine synthase expression was also significantly elevated during the early growth stage, likely contributing to the methionine supply required for various metabolic activities and active proliferation. Conversely, the cells showed sustained repression of carbonic anhydrase and ferredoxin hydrogenase, involved in the carbon concentrating mechanism, throughout the cultivation period under high CO2 conditions. This study also delved into the transcriptomic profiles in the Calvin cycle, nitrogen reductase, and lipid synthesis. Particularly, Chlorella sp. ABC-001 showed high expression levels of genes involved in lipid synthesis, such as glycerol-3-phosphate dehydrogenase and phospholipid-diacylglycerol acyltransferase. These findings suggest potential targets for metabolic engineering aimed at enhancing lipid production in microalgae. CONCLUSIONS We expect that our findings will help understand the carbon concentrating mechanism, photosynthesis, nitrogen assimilation, and lipid accumulation metabolisms of green algae according to CO2 concentrations. This study also provides insights into systems metabolic engineering of microalgae for improved performance in the future.
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Affiliation(s)
- Hyun Gi Koh
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jun Muk Cho
- Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Seungjib Jeon
- Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Yong Keun Chang
- Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Bongsoo Lee
- Department of Microbial Biotechnology, College of Science and Technology, Mokwon University, 88 Doanbuk-ro, Seo-gu, Daejeon, 35349, Republic of Korea.
| | - Nam Kyu Kang
- Department of Chemical Engineering, College of Engineering, Kyung Hee University, Yongin, 17104, Republic of Korea.
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Je S, Yamaoka Y. Biotechnological Approaches for Biomass and Lipid Production Using Microalgae Chlorella and Its Future Perspectives. J Microbiol Biotechnol 2022; 32:1357-1372. [PMID: 36310359 PMCID: PMC9720082 DOI: 10.4014/jmb.2209.09012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/12/2022] [Accepted: 10/17/2022] [Indexed: 11/05/2022]
Abstract
Heavy reliance on fossil fuels has been associated with increased climate disasters. As an alternative, microalgae have been proposed as an effective agent for biomass production. Several advantages of microalgae include faster growth, usage of non-arable land, recovery of nutrients from wastewater, efficient CO2 capture, and high amount of biomolecules that are valuable for humans. Microalgae Chlorella spp. are a large group of eukaryotic, photosynthetic, unicellular microorganisms with high adaptability to environmental variations. Over the past decades, Chlorella has been used for the large-scale production of biomass. In addition, Chlorella has been actively used in various food industries for improving human health because of its antioxidant, antidiabetic, and immunomodulatory functions. However, the major restrictions in microalgal biofuel technology are the cost-consuming cultivation, processing, and lipid extraction processes. Therefore, various trials have been performed to enhance the biomass productivity and the lipid contents of Chlorella cells. This study provides a comprehensive review of lipid enhancement strategies mainly published in the last five years and aimed at regulating carbon sources, nutrients, stresses, and expression of exogenous genes to improve biomass production and lipid synthesis.
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Affiliation(s)
- Sujeong Je
- Division of Biotechnology, The Catholic University of Korea, Bucheon 14662, Republic of Korea
| | - Yasuyo Yamaoka
- Division of Biotechnology, The Catholic University of Korea, Bucheon 14662, Republic of Korea,Corresponding author Phone: +82-2-2164-4034 Fax: +82-2-2164-4778 E-mail:
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Seon G, Kim HS, Cho JM, Kim M, Park WK, Chang YK. Effect of post-treatment process of microalgal hydrolysate on bioethanol production. Sci Rep 2020; 10:16698. [PMID: 33028886 PMCID: PMC7542428 DOI: 10.1038/s41598-020-73816-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 08/24/2020] [Indexed: 11/14/2022] Open
Abstract
Microalgae accumulate abundant lipids and are a promising source for biodiesel. However, carbohydrates account for 40% of microalgal biomass, an important consideration when using them for the economically feasible production of biodiesel. In this study, different acid hydrolysis and post-treatment processing of Chlorella sp. ABC-001 was performed, and the effect of these different hydrolysates on bioethanol yield by Saccharomyces cerevisiae KL17 was evaluated. For hydrolysis using H2SO4, the neutralization using Ca(OH)2 led to a higher yield (0.43 g ethanol/g sugars) than NaOH (0.27 g ethanol/g sugars). Application of electrodialysis to the H2SO4 + NaOH hydrolysate increased the yield to 0.35 g ethanol/g sugars, and K+ supplementation further enhanced the yield to 0.41 g ethanol/g sugars. Hydrolysis using HNO3 led to the generation of reactive species. Neutralization using only NaOH yielded 0.02 g ethanol/g sugars, and electrodialysis provided only a slight enhancement (0.06 g ethanol/g sugars). However, lowering the levels of reactive species further increased the yield to 0.25 g ethanol/g sugars, and K+ supplementation increased the yield to 0.35 g ethanol/g sugars. Overall, hydrolysis using H2SO4 + Ca(OH)2 provided the highest ethanol yield, and the yield was almost same as from conventional medium. This research emphasizes the importance of post-treatment processing that is modified for the species or strains used for bioethanol fermentation.
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Affiliation(s)
- Gyeongho Seon
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Hee Su Kim
- Daegu Center, Korea Basic Science Institute (KBSI), 80 Daehak-ro, Daegu, 41566, Republic of Korea
| | - Jun Muk Cho
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Minsik Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Won-Kun Park
- Department of Chemistry and Energy Engineering, Sangmyung University, Seoul, 03016, Republic of Korea.
| | - Yong Keun Chang
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea. .,Advanced Biomass R&D Center, Daejeon, 34141, Republic of Korea.
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