Advances in genetic engineering of marine algae

Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, Shandong, China. Electronic address: .
Biotechnology advances (Impact Factor: 9.02). 05/2012; 30(6):1602-13. DOI: 10.1016/j.biotechadv.2012.05.004
Source: PubMed


Algae are a component of bait sources for animal aquaculture, and they produce abundant valuable compounds for the chemical industry and human health. With today's fast growing demand for algae biofuels and the profitable market for cosmetics and pharmaceuticals made from algal natural products, the genetic engineering of marine algae has been attracting increasing attention as a crucial systemic technology to address the challenge of the biomass feedstock supply for sustainable industrial applications and to modify the metabolic pathway for the more efficient production of high-value products. Nevertheless, to date, only a few marine algae species can be genetically manipulated. In this article, an updated account of the research progress in marine algal genomics is presented along with methods for transformation. In addition, vector construction and gene selection strategies are reviewed. Meanwhile, a review on the progress of bioreactor technologies for marine algae culture is also revisited.

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Available from: Hanzhi Lin, Jan 07, 2014
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    • "protein, carbohydrate and lipid) in algae (Geider and La Roche 2002). Molecular N:P ratios thereby can provide an integrated measure of the ability of nutrient uptake for algal cells (Beardall et al. 2001a; Fresnedo and Serra 1992; Qin et al. 2012). Thus, N limitation usually results in low protein content and high carbohydrate or lipid storage (Shifrin and Chisholm 1981; Ganf et al. 1986) while P limitation can also shift the relative contents of protein, lipid and carbohydrate in algal cells (Theodorou et al. 1991; Reitan et al. 1994). "
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    ABSTRACT: The understanding of how nitrogen (N) to phosphorus (P) ratios regulate growth and chemical composition of algae is important to control the nutritional value of microalgae for industrial application. This study compared the impacts of N:P ratio manipulations on the growth, elements, lipid, fatty acids and protein contents of Tisochrysis lutea and Nannochloropsis oculata. F/2 medium was used as the basal formula to obtained six N:P ratios of 5:1, 10:1, 20:1, 30:1, 60:1 and 120:1 and tested on the algae species in triplicate. Growth rate was similar in both algal species across all N:P ratios, and the carbon content in T. lutea was higher than in N. oculata. However, the carbon contents were high in the N:P ratios of 5:1 and 120:1 and low from 10:1 to 60:1 N:P ratios for both T. lutea and N. oculata. There were no significant differences in cellular N and P, but the protein contents depended on algae species and were significantly affected by N:P ratios. The N:P ratio of 20:1 favoured algal growth and protein content, while the N:P ratio of 120:1 reduced algal growth and protein synthesis but increased lipid in both algae. The 20:1 N:P ratio favoured eicosapentaenoic acid (EPA) production in N. oculata and the 30:1 N:P ratio favours docosahexaenoic acid (DHA) production in T. lutea. This study indicates that N:P ratio manipulation is an effective strategy to change biochemical composition in algae and N or P limitation tends to lower polyunsaturated fatty acids (PUFA) contents in algae.
    Journal of Applied Phycology 12/2014; DOI:10.1007/s10811-014-0495-z · 2.56 Impact Factor
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    • "Significant progress in strain development and sustainable cultivation technologies are required to reduce the currently high production costs for algal biomass that is produced phototrophically. To date, a few green microalgae species such as Chlamydomonas, Dunaliella or Chlorella, and heterokont microalgae such as Phaeodactylum or Nannochloropsis have been successfully transformed [23]. Beyond mere transformation, adequate tools for the actual expression of unselected transgenes are required: they have been efficiently demonstrated so far in only a few algal species. "
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    ABSTRACT: Microalgae are considered a promising source for various high value products, such as carotenoids, ω-3 and ω-6 polyunsaturated fatty acids (PUFA). The unicellular green alga Lobosphaera (Parietochloris) incisa is an outstanding candidate for the efficient phototrophic production of arachidonic acid (AA), an essential ω-6 PUFA for infant brain development and a widely used ingredient in the baby formula industry. Although phototrophic production of such algal products has not yet been established, estimated costs are considered to be 2-5 times higher than competing heterotrophic production costs. This alga accumulates unprecedented amounts of AA within triacylglycerols and the molecular pathway of AA biosynthesis in L. incisa has been previously elucidated. Thus, progress in transformation and metabolic engineering of this high value alga could be exploited for increasing the efficient production of AA at competitive prices. We describe here the first successful transformation of L. incisa using the ble gene as a selection marker, under the control of the endogenous RBCS promoter. Furthermore, we have succeeded in the functional complementation of the L. incisa mutant strain P127, containing a mutated, inactive version of the delta-5 (Δ5) fatty acid desaturase gene. A copy of the functional Δ5 desaturase gene, linked to the ble selection marker, was transformed into the P127 mutant. The resulting transformants selected for zeocine resistant, had AA biosynthesis partially restored, indicating the functional complementation of the mutant strain with the wild-type gene. The results of this study present a platform for the successful genetic engineering of L. incisa and its long-chain PUFA metabolism.
    PLoS ONE 08/2014; 9(8):e105223. DOI:10.1371/journal.pone.0105223 · 3.23 Impact Factor
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    • "Among the various methods established, agitation with glass beads needs protoplast generation [3]–[5], silicon carbon whiskers based-method has been reported to be toxic to human [5], [6], electroporation [5]–[7], [9] and biolistic microparticle bombardment [5]–[7] needs expensive instrumentation and protoplast generation, and Agrobacterium tumefaciens-mediated gene transfer is inefficient [5]–[8], [10]. Hence, in spite of such efforts, genetic engineering in eukaryotic microalgae is not well-established, compared with bacterial transformation [2], [5], [7], [11]–[13]. "
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    ABSTRACT: Genetic engineering in microalgae is gaining attraction but nuclear transformation methods available so far are either inefficient or require special equipment. In this study, we employ positively charged nanoparticles, 3-aminopropyl-functionalized magnesium phyllosilicate (aminoclay, approximate unit cell composition of [H2N(CH2)3]8Si8Mg6O12(OH)4), for nuclear transformation into eukaryotic microalgae. TEM and EDX analysis of the process of transformation reveals that aminoclay coats negatively-charged DNA biomolecules and forms a self-assembled hybrid nanostructure. Subsequently, when this nanostructure is mixed with microalgal cells and plated onto selective agar plates with high friction force, cell wall is disrupted facilitating delivery of plasmid DNA into the cell and ultimately to the nucleus. This method is not only simple, inexpensive, and non-toxic to cells but also provides efficient transformation (5.03×102 transformants/µg DNA), second only to electroporation which needs advanced instrumentation. We present optimized parameters for efficient transformation including pre-treatment, friction force, concentration of foreign DNA/aminoclay, and plasticity of agar plates. It is also confirmed the successful integration and stable expression of foreign gene in Chlamydomonas reinhardtii through molecular methods.
    PLoS ONE 07/2014; 9(7):e101018. DOI:10.1371/journal.pone.0101018 · 3.23 Impact Factor
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