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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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Roager L, Kempen PJ, Bentzon-Tilia M, Sonnenschein EC, Gram L. Impact of host species on assembly, composition, and functional profiles of phycosphere microbiomes. mSystems 2024; 9:e0058324. [PMID: 39082797 PMCID: PMC11334532 DOI: 10.1128/msystems.00583-24] [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: 04/24/2024] [Accepted: 07/01/2024] [Indexed: 08/21/2024] Open
Abstract
Microalgal microbiomes play vital roles in the growth and health of their host, however, their composition and functions remain only partially characterized, especially across microalgal phyla. In this study, a natural seawater microbiome was introduced to three distinct, axenic species of microalgae, the haptophyte Isochrysis galbana, the chlorophyte Tetraselmis suecica, and the diatom Conticribra weissflogii (previously Thalassiosira), and its divergence and assembly under constant illumination was monitored over 49 days using 16S rRNA amplicon and metagenomic analyses. The microbiomes had a high degree of host specificity in terms of taxonomic composition and potential functions, including CAZymes profiles. Rhodobacteraceae and Flavobacteriaceae families were abundant across all microalgal hosts, but I. galbana microbiomes diverged further from T. suecica and C. weissflogii microbiomes. I. galbana microbiomes had a much higher relative abundance of Flavobacteriaceae, whereas the two other algal microbiomes had higher relative abundances of Rhodobacteraceae. This could be due to the bacterivorous mixotrophic nature of I. galbana affecting the carbohydrate composition available to the microbiomes, which was supported by the CAZymes profile of I. galbana microbiomes diverging further from those of T. suecica and C. weissflogii microbiomes. Finally, the presence of denitrification and other anaerobic pathways was found exclusively in the microbiomes of C. weissflogii, which we speculate could be a result of anoxic microenvironments forming in aggregates formed by this diatom during the experiment. These results underline the significant role of the microalgal host species on microbiome composition and functional profiles along with other factors, such as the trophic mode of the microalgal host. IMPORTANCE As the main primary producers of the oceans, microalgae serve as cornerstones of the ecosystems they are part of. Additionally, they are increasingly used for biotechnological purposes such as the production of nutraceuticals, pigments, and antioxidants. Since the bacterial microbiomes of microalgae can affect their hosts in beneficial and detrimental ways, understanding these microbiomes is crucial to both the ecological and applied roles of microalgae. The present study advances the understanding of microalgal microbiome assembly, composition, and functionality across microalgal phyla, which may inform the modeling and engineering of microalgal microbiomes for biotechnological purposes.
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Affiliation(s)
- Line Roager
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Paul J. Kempen
- DTU Nanolab, National Center for Nano Fabrication and Characterization, Technical University of Denmark, Kgs. Lyngby, Denmark
- Department of Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Mikkel Bentzon-Tilia
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Eva C. Sonnenschein
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lone Gram
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
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Wang S, Zhou X, Wu S, Zhao M, Hu Z. Transcriptomic and metabolomic analyses revealed regulation mechanism of mixotrophic Cylindrotheca sp. glycerol utilization and biomass promotion. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:84. [PMID: 37208696 DOI: 10.1186/s13068-023-02338-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 05/08/2023] [Indexed: 05/21/2023]
Abstract
BACKGROUND Diatoms have been viewed as ideal cell factories for production of some high-value bioactive metabolites, such as fucoxanthin, but their applications are restrained by limited biomass yield. Mixotrophy, by using both CO2 and organic carbon source, is believed effective to crack the bottleneck of biomass accumulation and achieve a sustainable bioproduct supply. RESULTS Glycerol, among tested carbon sources, was proved as the sole that could significantly promote growth of Cylindrotheca sp. with illumination, a so-called growth pattern, mixotrophy. Biomass and fucoxanthin yields of Cylindrotheca sp., grown in medium with glycerol (2 g L-1), was increased by 52% and 29%, respectively, as compared to the autotrophic culture (control) without compromise in photosynthetic performance. As Cylindrotheca sp. was unable to use glycerol without light, a time-series transcriptomic analysis was carried out to elucidate the light regulation on glycerol utilization. Among the genes participating in glycerol utilization, GPDH1, TIM1 and GAPDH1, showed the highest dependence on light. Their expressions decreased dramatically when the alga was transferred from light into darkness. Despite the reduced glycerol uptake in the dark, expressions of genes associating with pyrimidine metabolism and DNA replication were upregulated when Cylindrotheca sp. was cultured mixotrophically. Comparative transcriptomic and metabolomic analyses revealed amino acids and aminoacyl-tRNA metabolisms were enhanced at different timepoints of diurnal cycles in mixotrophic Cylindrotheca sp., as compared to the control. CONCLUSIONS Conclusively, this study not only provides an alternative for large-scale cultivation of Cylindrotheca, but also pinpoints the limiting enzymes subject to further metabolic manipulation. Most importantly, the novel insights in this study should aid to understand the mechanism of biomass promotion in mixotrophic Cylindrotheca sp.
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Affiliation(s)
- Song Wang
- Guangdong Technology Research Center for Marine Algal Bioengineering; Guangdong Provincial Key Laboratory for Plant Epigenetics; Shenzhen Engineering Laboratory for Marine Algal Biotechnology; Longhua Innovation Institute for Biotechnology; College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Xiyi Zhou
- Guangdong Technology Research Center for Marine Algal Bioengineering; Guangdong Provincial Key Laboratory for Plant Epigenetics; Shenzhen Engineering Laboratory for Marine Algal Biotechnology; Longhua Innovation Institute for Biotechnology; College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
| | - Sha Wu
- Guangdong Technology Research Center for Marine Algal Bioengineering; Guangdong Provincial Key Laboratory for Plant Epigenetics; Shenzhen Engineering Laboratory for Marine Algal Biotechnology; Longhua Innovation Institute for Biotechnology; College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Mengkai Zhao
- Guangdong Technology Research Center for Marine Algal Bioengineering; Guangdong Provincial Key Laboratory for Plant Epigenetics; Shenzhen Engineering Laboratory for Marine Algal Biotechnology; Longhua Innovation Institute for Biotechnology; College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Zhangli Hu
- Guangdong Technology Research Center for Marine Algal Bioengineering; Guangdong Provincial Key Laboratory for Plant Epigenetics; Shenzhen Engineering Laboratory for Marine Algal Biotechnology; Longhua Innovation Institute for Biotechnology; College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China.
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The Effect of Trophic Modes on Biomass and Lipid Production of Five Microalgal Strains. WATER 2022. [DOI: 10.3390/w14020240] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Five microalgae strains, namely Isochrysis galbana, Microchloropsis gaditana, Scenedesmus obliquus, Nannochloropsis oculata and Tetraselmis suecica, were selected as potential candidates for polyunsaturated fatty acids’ production, evaluating biomass productivity and their capacity to accumulate high lipid contents under different trophic modes. Microalgae strains were cultivated in the presence of 1% glucose using mixotrophic and heterotrophic conditions, while autotrophic cultures served as control experiments. The results demonstrate that S. obliquus performed the highest biomass productivity that reached 0.13 and 0.14 g L−1 d−1 under mixotrophic and heterotrophic conditions, respectively. I. galbana and S. obliquus utilized elevated contents of glucose in mixotrophy, removing 55.9% and 95.6% of the initial concentration of the carbohydrate, respectively, while glucose consumption by the aforementioned strains also remained high under heterotrophic cultivation. The production of lipids was maximal for I. galbana in mixotrophy and S. obliquus in heterotrophy, performing lipid productivities of 24.85 and 22.77 mg L−1 d−1, respectively. The most abundant saturated acid detected for all microalgae strains evaluated was palmitic acid (C16:0), while oleic and linolenic acids (C18:1n9c/C18:3n3) comprised the most abundant unsaturated fatty acids. I. galbana performed the highest linoleic acid (C18:2n6c) content under heterotrophic nutrition, which reached 87.9 mg g−1 of ash-free dry weight. Among the microalgae strains compared, the biomass and lipid production monitored for I. galbana and S. obliquus confirm that both strains could serve as efficient bioproducers for application in algal biorefineries.
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Yun HS, Kim YS, Yoon HS. Effect of Different Cultivation Modes (Photoautotrophic, Mixotrophic, and Heterotrophic) on the Growth of Chlorella sp. and Biocompositions. Front Bioeng Biotechnol 2022; 9:774143. [PMID: 34976972 PMCID: PMC8718857 DOI: 10.3389/fbioe.2021.774143] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 11/26/2021] [Indexed: 11/18/2022] Open
Abstract
In the past, biomass production using microalgae culture was dependent on inorganic carbon sources as microalgae are photosynthetic organisms. However, microalgae utilize both organic and inorganic carbon sources, such as glucose. Glucose is an excellent source of organic carbon that enhances biomass yield and the content of useful substances in microalgae. In this study, photoautotrophic, mixotrophic, and heterotrophic cultivation conditions were applied to three well-known strains of Chlorella (KNUA104, KNUA114, and KNUA122) to assess biomass productivity, and compositional changes (lipid, protein, and pigment) were evaluated in BG11 media under photoautotrophic, mixotrophic, and heterotrophic conditions utilizing different initial concentrations of glucose (5, 10, 15, 20, and 25 g L−1). Compared to the photoautotrophic condition (biomass yield: KNUA104, 0.35 ± 0.04 g/L/d; KNUA114, 0.40 ± 0.08 g/L/d; KNUA122, 0.38 ± 0.05 g/L/d) glucose was absent, and the biomass yield improved in the mixotrophic (glucose: 20 g L−1; biomass yield: KNUA104, 2.99 ± 0.10 g/L/d; KNUA114, 5.18 ± 0.81 g/L/d; KNUA122, 5.07 ± 0.22 g/L/d) and heterotrophic conditions (glucose: 20 g L−1; biomass yield: KNUA104, 1.72 ± 0.26 g/L/d; KNUA114, 4.26 ± 0.27 g/L/d; KNUA122, 4.32 ± 0.32 g/L/d). All strains under mixotrophic and heterotrophic conditions were optimally cultured when 15–20 g L−1 initial glucose was provided. Although bioresourse productivity improved under both mixotrophic and heterotrophic conditions where mixotrophic conditions were found to be optimal as the yields of lipid and pigment were also enhanced. Protein content was less affected by the presence of light or the concentration of glucose. Under mixotrophic conditions, the highest lipid content (glucose: 15 g L−1; lipid content: 68.80 ± 0.54%) was obtained with Chlorella vulgaris KNUA104, and enhanced pigment productivity of Chlorella sorokiniana KNUA114 and KNUA122 (additional pigment yield obtained with 15 g L−1 glucose: KNUA 114, 0.33 ± 0.01 g L−1; KNUA122, 0.21 ± 0.01 g L−1). Also, saturated fatty acid (SFA) content was enhanced in all strains (SFA: KNUA104, 29.76 ± 1.31%; KNUA114, 37.01 ± 0.98%; KNUA122, 33.37 ± 0.17%) under mixotrophic conditions. These results suggest that mixotrophic cultivation of Chlorella vulgaris and Chlorella sorokiniana could improve biomass yield and the raw material quality of biomass.
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Affiliation(s)
- Hyun-Sik Yun
- School of Life Sciences, BK21 FOUR KNU Creative BioResearch Group, Kyungpook National University, Daegu, South Korea
| | - Young-Saeng Kim
- Research Institute of Ulleung-do & Dok-do, Kyungpook National University, Daegu, South Korea
| | - Ho-Sung Yoon
- School of Life Sciences, BK21 FOUR KNU Creative BioResearch Group, Kyungpook National University, Daegu, South Korea.,Advanced Bio-Resource Research Center, Kyungpook National University, Daegu, South Korea.,Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea
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Capa-Robles W, García-Mendoza E, Paniagua-Michel JDJ. Enhanced β-carotene and Biomass Production by Induced Mixotrophy in Dunaliella salina across a Combined Strategy of Glycerol, Salinity, and Light. Metabolites 2021; 11:metabo11120866. [PMID: 34940624 PMCID: PMC8708783 DOI: 10.3390/metabo11120866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/03/2021] [Accepted: 12/09/2021] [Indexed: 11/24/2022] Open
Abstract
Current mixotrophic culture systems for Dunaliella salina have technical limitations to achieve high growth and productivity. The purpose of this study was to optimize the mixotrophic conditions imposed by glycerol, light, and salinity that lead to the highest biomass and β-carotene yields in D. salina. The combination of 12.5 mM glycerol, 3.0 M salinity, and 50 μmol photons m−2 s−1 light intensity enabled significant assimilation of glycerol by D. salina and consequently enhanced growth (2.1 × 106 cell mL−1) and β-carotene accumulation (4.43 pg cell−1). The saline and light shock induced the assimilation of glycerol by this microalga. At last stage of growth, the increase in light intensity (300 μmol photons m−2 s−1) caused the β-carotene to reach values higher than 30 pg cell−1 and tripled the β-carotene values obtained from photoautotrophic cultures using the same light intensity. Increasing the salt concentration from 1.5 to 3.0 M NaCl (non-isosmotic salinity) produced higher growth and microalgal β-carotene than the isosmotic salinity 3.0 M NaCl. The mixotrophic strategy developed in this work is evidenced in the metabolic capability of D. salina to use both photosynthesis and organic carbon, viz., glycerol that leads to higher biomass and β-carotene productivity than that of an either phototrophic or heterotrophic process alone. The findings provide insights into the key role of exogenous glycerol with a strategic combination of salinity and light, which evidenced unknown roles of this polyol other than that in osmoregulation, mainly on the growth, pigment accumulation, and carotenogenesis of D. salina.
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Affiliation(s)
- Willian Capa-Robles
- Department of Marine Biotechnology, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), 22860 Ensenada, Baja California, Mexico;
| | - Ernesto García-Mendoza
- Department of Biological Oceanography, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), 22860 Ensenada, Baja California, Mexico;
| | - José de Jesús Paniagua-Michel
- Department of Marine Biotechnology, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), 22860 Ensenada, Baja California, Mexico;
- Correspondence: ; Tel.: +52-646-1745050
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Yun HS, Kim YS, Yoon HS. Enhancement of Biomass Production in Colony-Forming Green Algae, Botryosphaerella sudetica, Under Mixotrophic Cultivation. Front Genet 2021; 12:669702. [PMID: 34149810 PMCID: PMC8212961 DOI: 10.3389/fgene.2021.669702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/26/2021] [Indexed: 11/13/2022] Open
Abstract
In this study, we characterized the potential of colony-forming green algae, Botryosphaerella sudetica KNUA107, isolated from Ulleung Island, South Korea, as a bioresource and analyzed the effects of mixotrophic cultivation on its bioresource production efficiency. Internal transcribed spacer (ITS) (ITS1, 5.8S, and ITS2), ribulose bisphosphate carboxylase large subunit (rbcL), and elongation factor Tu (tufa) regions were used for molecular identification and phylogenetic analysis. B. sudetica KNUA107 had a strong relationship with the green algae of Botryococcus and Botryosphaerella genera, which are colony-forming species, and was also associated with members of the Neochloris genus. To improve biomass productivity, we tested mixotrophic cultivation conditions using several organic carbon sources. Glucose supplementation stimulated B. sudetica KNUA107 growth and reduced the time needed to reach the stationary phase. In addition, the colony size was 1.5–2.0 times larger with glucose than in photoautotrophic cultures, and settleability improved in proportion to colony size. The total lipid content and biomass productivity were also higher in cultures supplemented with glucose. Among the lipid components, saturated fatty acids and monounsaturated fatty acids had the highest proportion. Our study suggests that B. sudetica KNUA107, which has enhanced efficiency in biomass production and lipid components under mixotrophic cultivation, has high potential as a bioresource.
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Affiliation(s)
- Hyun-Sik Yun
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea.,BK21 FOUR KNU Creative BioResearch Group, School of Life Sciences, Kyungpook National University, Daegu, South Korea
| | - Young-Saeng Kim
- Research Institute of Ulleung-do and Dok-do, Kyungpook National University, Daegu, South Korea
| | - Ho-Sung Yoon
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, South Korea.,BK21 FOUR KNU Creative BioResearch Group, School of Life Sciences, Kyungpook National University, Daegu, South Korea
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