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Yan T, Wang K, Feng K, Gao X, Jin Y, Wu H, Zhang W, Wei L. Remodeling of the 3D chromatin architecture in the marine microalga Nannochloropsis oceanica during lipid accumulation. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:129. [PMID: 37592325 PMCID: PMC10436460 DOI: 10.1186/s13068-023-02378-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/29/2023] [Indexed: 08/19/2023]
Abstract
BACKGROUND Genomic three-dimensional (3D) spatial organization plays a key role in shaping gene expression and associated chromatin modification, and it is highly sensitive to environmental stress conditions. In microalgae, exposure to nitrogen stress can drive lipid accumulation, yet the associated functional alterations in the spatial organization of the microalgal genome have yet to be effectively characterized. RESULTS Accordingly, the present study employed RNA-seq, Hi-C, and ChIP-seq approaches to explore the relationship between 3D chromosomal architecture and gene expression during lipid accumulation in the marine microalga Nannochloropsis oceanica in response to nitrogen deprivation (ND). These analyses revealed that ND resulted in various changes in chromosomal organization, including A/B compartment transitions, topologically associating domain (TAD) shifts, and the disruption of short-range interactions. Significantly higher levels of gene expression were evident in A compartments and TAD boundary regions relative to B compartments and TAD interior regions, consistent with observed histone modification enrichment in these areas. ND-induced differentially expressed genes (DEGs) were notably enriched in altered TAD-associated regions and regions exhibiting differential genomic contact. These DEGs were subjected to Gene Ontology (GO) term analyses that indicated they were enriched in the 'fatty acid metabolism', 'response to stress', 'carbon fixation' and 'photosynthesis' functional categories, in line with the ND treatment conditions used to conduct this study. These data indicate that Nannochloropsis cells exhibit a clear association between chromatin organization and transcriptional activity under nitrogen stress conditions. Pronounced and extensive histone modifications were evident in response to ND. Observed changes in chromatin architecture were linked to shifts in histone modifications and gene expression. CONCLUSIONS Overall, the reprogramming of many lipid metabolism-associated genes was evident under nitrogen stress conditions with respect to both histone modifications and chromosomal organization. Together these results revealed that higher-order chromatin architecture represents a new layer that can guide efforts to understand the transcriptional regulation of lipid metabolism in nitrogen-deprived microalgae.
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Affiliation(s)
- Tongtong Yan
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, 571158, China
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou, 571129, China
| | - Kexin Wang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, 571158, China
| | - Kexin Feng
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, 571158, China
| | - Xiangchen Gao
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, 571158, China
| | - Yinghong Jin
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, 571158, China
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou, 571129, China
| | - Hongping Wu
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, 571158, China
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou, 571129, China
| | - Wenfei Zhang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, 571158, China
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou, 571129, China
| | - Li Wei
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, 571158, China.
- Hainan Observation and Research Station of Dongzhaigang Mangrove Wetland Ecosystem, Haikou, 571129, China.
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Aoki K, Yamamoto K, Ohkuma M, Sugita T, Tanaka N, Takashima M. Hyphal Growth in Trichosporon asahii Is Accelerated by the Addition of Magnesium. Microbiol Spectr 2023; 11:e0424222. [PMID: 37102973 PMCID: PMC10269644 DOI: 10.1128/spectrum.04242-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 04/10/2023] [Indexed: 04/28/2023] Open
Abstract
Fungal dimorphism involves two morphologies: a unicellular yeast cell and a multicellular hyphal form. Invasion of hyphae into human cells causes severe opportunistic infections. The transition between yeast and hyphal forms is associated with the virulence of fungi; however, the mechanism is poorly understood. Therefore, we aimed to identify factors that induce hyphal growth of Trichosporon asahii, a dimorphic basidiomycete that causes trichosporonosis. T. asahii showed poor growth and formed small cells containing large lipid droplets and fragmented mitochondria when cultivated for 16 h in a nutrient-deficient liquid medium. However, these phenotypes were suppressed via the addition of yeast nitrogen base. When T. asahii cells were cultivated in the presence of different compounds present in the yeast nitrogen base, we found that magnesium sulfate was a key factor for inducing cell elongation, and its addition dramatically restored hyphal growth in T. asahii. In T. asahii hyphae, vacuoles were enlarged, the size of lipid droplets was decreased, and mitochondria were distributed throughout the cell cytoplasm and adjacent to the cell walls. Additionally, hyphal growth was disrupted due to treatment with an actin inhibitor. The actin inhibitor latrunculin A disrupted the mitochondrial distribution even in hyphal cells. Furthermore, magnesium sulfate treatment accelerated hyphal growth in T. asahii for 72 h when the cells were cultivated in a nutrient-deficient liquid medium. Collectively, our results suggest that an increase in magnesium levels triggers the transition from the yeast to hyphal form in T. asahii. These findings will support studies on the pathogenesis of fungi and aid in developing treatments. IMPORTANCE Understanding the mechanism underlying fungal dimorphism is crucial to discern its invasion into human cells. Invasion is caused by the hyphal form rather than the yeast form; therefore, it is important to understand the mechanism of transition from the yeast to hyphal form. To study the transition mechanism, we utilized Trichosporon asahii, a dimorphic basidiomycete that causes severe trichosporonosis since there are fewer studies on T. asahii than on ascomycetes. This study suggests that an increase in Mg2+, the most abundant mineral in living cells, triggers growth of filamentous hyphae and increases the distribution of mitochondria throughout the cell cytoplasm and adjacent to the cell walls in T. asahii. Understanding the mechanism of hyphal growth triggered by Mg2+ increase will provide a model system to explore fungal pathogenicity in the future.
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Affiliation(s)
- Keita Aoki
- Laboratory of Yeast Systematics, Tokyo NODAI Research Institute, Tokyo University of Agriculture, Setagaya, Tokyo, Japan
| | - Kosuke Yamamoto
- Department of Molecular Microbiology, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya, Tokyo, Japan
| | - Moriya Ohkuma
- Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
| | - Takashi Sugita
- Department of Microbiology, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan
| | - Naoto Tanaka
- Department of Molecular Microbiology, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya, Tokyo, Japan
| | - Masako Takashima
- Laboratory of Yeast Systematics, Tokyo NODAI Research Institute, Tokyo University of Agriculture, Setagaya, Tokyo, Japan
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Steensma AK, Shachar-Hill Y, Walker BJ. The carbon-concentrating mechanism of the extremophilic red microalga Cyanidioschyzon merolae. PHOTOSYNTHESIS RESEARCH 2023; 156:247-264. [PMID: 36780115 PMCID: PMC10154280 DOI: 10.1007/s11120-023-01000-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/27/2023] [Indexed: 05/03/2023]
Abstract
Cyanidioschyzon merolae is an extremophilic red microalga which grows in low-pH, high-temperature environments. The basis of C. merolae's environmental resilience is not fully characterized, including whether this alga uses a carbon-concentrating mechanism (CCM). To determine if C. merolae uses a CCM, we measured CO2 uptake parameters using an open-path infra-red gas analyzer and compared them to values expected in the absence of a CCM. These measurements and analysis indicated that C. merolae had the gas-exchange characteristics of a CCM-operating organism: low CO2 compensation point, high affinity for external CO2, and minimized rubisco oxygenation. The biomass δ13C of C. merolae was also consistent with a CCM. The apparent presence of a CCM in C. merolae suggests the use of an unusual mechanism for carbon concentration, as C. merolae is thought to lack a pyrenoid and gas-exchange measurements indicated that C. merolae primarily takes up inorganic carbon as carbon dioxide, rather than bicarbonate. We use homology to known CCM components to propose a model of a pH-gradient-based CCM, and we discuss how this CCM can be further investigated.
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Affiliation(s)
- Anne K Steensma
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
- Michigan State University - Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA
| | - Yair Shachar-Hill
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Berkley J Walker
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA.
- Michigan State University - Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, USA.
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Murakami M, Osanai T. Biochemical Properties of β-Amylase from Red Algae and Improvement of Its Thermostability through Immobilization. ACS OMEGA 2022; 7:36195-36205. [PMID: 36278071 PMCID: PMC9583313 DOI: 10.1021/acsomega.2c03315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
β-Amylase hydrolyzes polysaccharides, such as starch, into maltose. It is used as an industrial enzyme in the production of food and pharmaceuticals. The eukaryotic red alga Cyanidioschyzon merolae is a unicellular alga that grows at an optimum pH of 2.0-3.0 and an optimum temperature of 40-50 °C. By focusing on the thermostability and acid resistance of the proteins of C. merolae, we investigated the properties of β-amylase from C. merolae (hereafter CmBAM) and explored the possibility of using CmBAM as an industrial enzyme. CmBAM showed the highest activity at 47 °C and pH 6.0. CmBAM had a relatively higher specificity for amylose as a substrate than for starch. Immobilization of CmBAM on a silica gel carrier improved storage stability and thermostability, allowing the enzyme to be reused. The optimum temperature and pH of CmBAM were comparable to those of existing β-amylases from barley and wheat. C. merolae does not use amylose, but CmBAM has a substrate specificity for both amylose and amylopectin but not for glycogen. Among the several β-amylases reported, CmBAM was unique, with a higher specificity for amylose than for starch. The high specificity of CmBAM for amylose suggests that isoamylase and pullulanase, which cleave the α-1,6 bonds of starch, may act together in vivo. Compared with several reported immobilized plant-derived β-amylases, immobilized CmBAM was comparable to β-amylase, with the highest reusability and the third-highest storage stability at 30 days of storage. In addition, immobilized CmBAM has improved thermostability by 15-20 °C, which can lead to wider applications and easier handling.
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Stadnichuk IN, Tropin IV. Cyanidiales as Polyextreme Eukaryotes. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:472-487. [PMID: 35790381 DOI: 10.1134/s000629792205008x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/28/2022] [Accepted: 04/24/2022] [Indexed: 06/15/2023]
Abstract
Cyanidiales were named enigmatic microalgae due to their unique polyextreme properties, considered for a very long time unattainable for eukaryotes. Cyanidiales mainly inhabit hot sulfuric springs with high acidity (pH 0-4), temperatures up to 56°C, and ability to survive in the presence of dissolved heavy metals. Owing to the minimal for eukaryotes genome size, Cyanidiales have become one of the most important research objects in plant cell physiology, biochemistry, molecular biology, phylogenomics, and evolutionary biology. They play an important role in studying many aspects of oxygenic photosynthesis and chloroplasts origin. The ability to survive in stressful habitats and the corresponding metabolic pathways were acquired by Cyanidiales from archaea and bacteria via horizontal gene transfer (HGT). Thus, the possibility of gene transfer from prokaryotes to eukaryotes was discovered, which was a new step in understanding of the origin of eukaryotic cell.
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Affiliation(s)
- Igor N Stadnichuk
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, 127726, Russia.
| | - Ivan V Tropin
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
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Wei L, You W, Xu Z, Zhang W. Transcriptomic survey reveals multiple adaptation mechanisms in response to nitrogen deprivation in marine Porphyridium cruentum. PLoS One 2021; 16:e0259833. [PMID: 34793503 PMCID: PMC8601545 DOI: 10.1371/journal.pone.0259833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 09/28/2021] [Indexed: 11/19/2022] Open
Abstract
Single-cell red microalga Porphyridium cruentum is potentially considered to be the bioresource for biofuel and pharmaceutical production. Nitrogen is a kind of nutrient component for photosynthetic P. cruentum. Meanwhile, nitrogen stress could induce to accumulate some substances such as lipid and phycoerythrin and affect its growth and physiology. However, how marine microalga Porphyridium cruentum respond and adapt to nitrogen starvation remains elusive. Here, acclimation of the metabolic reprogramming to changes in the nutrient environment was studied by high-throughput mRNA sequencing in the unicellular red alga P. cruentum. Firstly, to reveal transcriptional regulation, de novo transcriptome was assembled and 8,244 unigenes were annotated based on different database. Secondly, under nitrogen deprivation, 2100 unigenes displayed differential expression (1134 upregulation and 966 downregulation, respectively) and some pathways including carbon/nitrogen metabolism, photosynthesis, and lipid metabolism would be reprogrammed in P. cruentum. The result demonstrated that nitrate assimilation (with related unigenes of 8–493 fold upregulation) would be strengthen and photosynthesis (with related unigenes of 6–35 fold downregulation) be impaired under nitrogen deprivation. Importantly, compared to other green algae, red microalga P. cruentum presented a different expression pattern of lipid metabolism in response to nitrogen stress. These observations will also provide novel insight for understanding adaption mechanisms and potential targets for metabolic engineering and synthetic biology in P. cruentum.
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Affiliation(s)
- Li Wei
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, China
- * E-mail: (LW); (WZ)
| | - Wuxin You
- Department of Plant Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Zhengru Xu
- College of Foreign Language, Hainan Normal University, Haikou, China
| | - Wenfei Zhang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, China
- * E-mail: (LW); (WZ)
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Pancha I, Takaya K, Tanaka K, Imamura S. The Unicellular Red Alga Cyanidioschyzon merolae, an Excellent Model Organism for Elucidating Fundamental Molecular Mechanisms and Their Applications in Biofuel Production. PLANTS 2021; 10:plants10061218. [PMID: 34203949 PMCID: PMC8232737 DOI: 10.3390/plants10061218] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/11/2021] [Accepted: 06/11/2021] [Indexed: 11/16/2022]
Abstract
Microalgae are considered one of the best resources for the production of biofuels and industrially important compounds. Various models have been developed to understand the fundamental mechanism underlying the accumulation of triacylglycerols (TAGs)/starch and to enhance its content in cells. Among various algae, the red alga Cyanidioschyzonmerolae has been considered an excellent model system to understand the fundamental mechanisms behind the accumulation of TAG/starch in the microalga, as it has a smaller genome size and various biotechnological methods are available for it. Furthermore, C. merolae can grow and survive under high temperature (40 °C) and low pH (2–3) conditions, where most other organisms would die, thus making it a choice alga for large-scale production. Investigations using this alga has revealed that the target of rapamycin (TOR) kinase is involved in the accumulation of carbon-reserved molecules, TAGs, and starch. Furthermore, detailed molecular mechanisms of the role of TOR in controlling the accumulation of TAGs and starch were uncovered via omics analyses. Based on these findings, genetic engineering of the key gene and proteins resulted in a drastic increment of the amount of TAGs and starch. In addition to these studies, other trials that attempted to achieve the TAG increment in C. merolae have been summarized in this article.
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Affiliation(s)
- Imran Pancha
- Department of Biological Sciences, SRM University-AP, Amaravati, Andhra Pradesh 522502, India
- Correspondence: (I.P.); (S.I.); Tel.: +81-422-59-6179 (S.I.)
| | - Kazuhiro Takaya
- NTT Space Environment and Energy Laboratories, Nippon Telegraph and Telephone Corporation, 3-9-11 Midori-cho, Musashino-shi, Tokyo 180-8585, Japan;
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1-29 Nagatsuta, Midori-ku, Yokohama-shi, Kanagawa 226-8503, Japan;
| | - Sousuke Imamura
- NTT Space Environment and Energy Laboratories, Nippon Telegraph and Telephone Corporation, 3-9-11 Midori-cho, Musashino-shi, Tokyo 180-8585, Japan;
- Correspondence: (I.P.); (S.I.); Tel.: +81-422-59-6179 (S.I.)
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Pancha I, Shima H, Higashitani N, Igarashi K, Higashitani A, Tanaka K, Imamura S. Target of rapamycin-signaling modulates starch accumulation via glycogenin phosphorylation status in the unicellular red alga Cyanidioschyzon merolae. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:485-499. [PMID: 30351485 DOI: 10.1111/tpj.14136] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 09/23/2018] [Accepted: 10/15/2018] [Indexed: 06/08/2023]
Abstract
The target of rapamycin (TOR) signaling pathway is involved in starch accumulation in various eukaryotic organisms; however, the molecular mechanism behind this phenomenon in eukaryotes has not been elucidated. We report a regulatory mechanism of starch accumulation by TOR in the unicellular red alga, Cyanidioschyzon merolae. The starch content in C. merolae after TOR-inactivation by rapamycin, a TOR-specific inhibitor, was increased by approximately 10-fold in comparison with its drug vehicle, dimethyl sulfoxide. However, our previous transcriptome analysis showed that the expression level of genes related to carbohydrate metabolism was unaffected by rapamycin, indicating that starch accumulation is regulated at post-transcriptional levels. In this study, we performed a phosphoproteome analysis using liquid chromatography-tandem mass spectrometry to investigate potential post-transcriptional modifications, and identified 52 proteins as candidate TOR substrates. Among the possible substrates, we focused on the function of CmGLG1, because its phosphorylation at the Ser613 residue was decreased after rapamycin treatment, and overexpression of CmGLG1 resulted in a 4.7-fold higher starch content. CmGLG1 is similar to the priming protein, glycogenin, which is required for the initiation of starch/glycogen synthesis, and a budding yeast complementation assay demonstrated that CmGLG1 can functionally substitute for glycogenin. We found an approximately 60% reduction in the starch content in a phospho-mimicking CmGLG1 overexpression strain, in which Ser613 was substituted with aspartic acid, in comparison with the wild-type CmGLG1 overexpression cells. Our results indicate that TOR modulates starch accumulation by changing the phosphorylation status of the CmGLG1 Ser613 residue in C. merolae.
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Affiliation(s)
- Imran Pancha
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
| | - Hiroki Shima
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Aoba-ku, Sendai, 980-8575, Japan
| | - Nahoko Higashitani
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Kazuhiko Igarashi
- Department of Biochemistry, Tohoku University Graduate School of Medicine, Seiryo-machi 2-1, Aoba-ku, Sendai, 980-8575, Japan
| | - Atsushi Higashitani
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
| | - Sousuke Imamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259-R1 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
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Zhang L, Pei H, Chen S, Jiang L, Hou Q, Yang Z, Yu Z. Salinity-induced cellular cross-talk in carbon partitioning reveals starch-to-lipid biosynthesis switching in low-starch freshwater algae. BIORESOURCE TECHNOLOGY 2018; 250:449-456. [PMID: 29197271 DOI: 10.1016/j.biortech.2017.11.067] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 11/17/2017] [Accepted: 11/22/2017] [Indexed: 05/10/2023]
Abstract
Salinity stress has been verified to be a successful approach to enhance lipid production in high-starch marine algae, and salinity-induced carbon flow switching has been proposed as an algal response specific to brackish water. With the aim of testing this assumption, Chlorella sorokiniana SDEC-18, a low-starch freshwater alga, was grown in BG11 medium with NaCl addition at various concentrations (0, 2, 5, 10, 20, and 30 g/L). The results showed that salinity stress promoted carbon redistribution and starch conversion to lipid. The most desirable lipid productivity of 19.66 mg/L·d occurred in the medium with 20 g/L NaCl, about 2.16 times as high as that in the BG11 medium control. Moreover, microalgae with salinity stress were able to produce biodiesel with a more suitable cloud point, due to a decrease in the saturated fatty acid content. This therefore confirms that low-starch freshwater microalgae can also carry out salinity-induced carbon flow switching.
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Affiliation(s)
- Lijie Zhang
- School of Environmental Science and Engineering, Shandong University, 27 Shanda Nan Road, Jinan 250100, China
| | - Haiyan Pei
- School of Environmental Science and Engineering, Shandong University, 27 Shanda Nan Road, Jinan 250100, China; Shandong Provincial Engineering Centre on Environmental Science and Technology, 17923 Jingshi Road, Jinan 250061, China.
| | - Shuaiqi Chen
- School of Environmental Science and Engineering, Shandong University, 27 Shanda Nan Road, Jinan 250100, China
| | - Liqun Jiang
- School of Environmental Science and Engineering, Shandong University, 27 Shanda Nan Road, Jinan 250100, China
| | - Qingjie Hou
- School of Environmental Science and Engineering, Shandong University, 27 Shanda Nan Road, Jinan 250100, China
| | - Zhigang Yang
- School of Environmental Science and Engineering, Shandong University, 27 Shanda Nan Road, Jinan 250100, China
| | - Ze Yu
- School of Environmental Science and Engineering, Shandong University, 27 Shanda Nan Road, Jinan 250100, China
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Nitrogen Starvation Impacts the Photosynthetic Performance of Porphyridium cruentum as Revealed by Chlorophyll a Fluorescence. Sci Rep 2017; 7:8542. [PMID: 28819147 PMCID: PMC5561210 DOI: 10.1038/s41598-017-08428-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 07/12/2017] [Indexed: 11/08/2022] Open
Abstract
Nitrogen is one of the most important nutrients needed for plants and algae to survive, and the photosynthetic ability of algae is related to nitrogen abundance. Red algae are unique photosynthetic eukaryotic organisms in the evolution of algae, as they contain phycobilisomes (PBSs) on their thylakoid membranes. In this report, the in vivo chlorophyll (Chl) a fluorescence kinetics of nitrogen-starved Porphyridium cruentum were analyzed to determine the effects of nitrogen deficiency on photosynthetic performance using a multi-color pulse amplitude modulation (PAM) chlorophyll fluorometer. Due to nitrogen starvation, the photochemical efficiency of PSII and the activity of PSII reaction centers (RCs) decreased, and photoinhibition of PSII occurred. The water-splitting system on the donor side of PSII was seriously impacted by nitrogen deficiency, leading to the inactivation of the oxygen-evolving complex (OEC) and decreased light energy conversion efficiency. In nitrogen-starved cells, a higher proportion of energy was used for photochemical reactions, and thermal dissipation was reduced, as shown by qP and qN. The ability of nitrogen-starved cells to tolerate and resist high photon flux densities was weakened. Our results showed that the photosynthetic performance of P. cruentum was severely impacted by nitrogen deficiency.
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Kawase Y, Imamura S, Tanaka K. A MYB-type transcription factor, MYB2, represses light-harvesting protein genes in Cyanidioschyzon merolae. FEBS Lett 2017; 591:2439-2448. [PMID: 28748638 DOI: 10.1002/1873-3468.12763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 11/07/2022]
Abstract
While searching for transcriptional regulators that respond to changes in light regimes, we identified a MYB domain-containing protein, MYB2, that accumulates under dark and other conditions in the unicellular red alga Cyanidioschyzon merolae. The isolation and analysis of a MYB2 mutant revealed that MYB2 represses the expression of the nuclear-encoded chloroplast RNA polymerase sigma factor gene SIG2, which results in the repression of the chloroplast-encoded phycobilisome genes that are under its control. Since nuclear-encoded phycobilisome and other light-harvesting protein genes are also repressed by MYB2, we conclude that MYB2 has a role in repressing the expression of light-harvesting genes. The MYB2 mutant is sensitive to a prolonged dark incubation, indicating the importance of MYB2 for cell viability in the dark.
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Affiliation(s)
- Yasuko Kawase
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan.,Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama, Japan
| | - Sousuke Imamura
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
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Lipid metabolism and potentials of biofuel and high added-value oil production in red algae. World J Microbiol Biotechnol 2017; 33:74. [DOI: 10.1007/s11274-017-2236-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 03/01/2017] [Indexed: 10/20/2022]
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Fu W, Chaiboonchoe A, Khraiwesh B, Nelson DR, Al-Khairy D, Mystikou A, Alzahmi A, Salehi-Ashtiani K. Algal Cell Factories: Approaches, Applications, and Potentials. Mar Drugs 2016; 14:md14120225. [PMID: 27983586 PMCID: PMC5192462 DOI: 10.3390/md14120225] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/02/2016] [Accepted: 12/05/2016] [Indexed: 12/26/2022] Open
Abstract
With the advent of modern biotechnology, microorganisms from diverse lineages have been used to produce bio-based feedstocks and bioactive compounds. Many of these compounds are currently commodities of interest, in a variety of markets and their utility warrants investigation into improving their production through strain development. In this review, we address the issue of strain improvement in a group of organisms with strong potential to be productive “cell factories”: the photosynthetic microalgae. Microalgae are a diverse group of phytoplankton, involving polyphyletic lineage such as green algae and diatoms that are commonly used in the industry. The photosynthetic microalgae have been under intense investigation recently for their ability to produce commercial compounds using only light, CO2, and basic nutrients. However, their strain improvement is still a relatively recent area of work that is under development. Importantly, it is only through appropriate engineering methods that we may see the full biotechnological potential of microalgae come to fruition. Thus, in this review, we address past and present endeavors towards the aim of creating productive algal cell factories and describe possible advantageous future directions for the field.
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Affiliation(s)
- Weiqi Fu
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Amphun Chaiboonchoe
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Basel Khraiwesh
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - David R Nelson
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Dina Al-Khairy
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Alexandra Mystikou
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Amnah Alzahmi
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Kourosh Salehi-Ashtiani
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
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