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: 8.91). 05/2012; 30(6):1602-13. DOI: 10.1016/j.biotechadv.2012.05.004
Source: PubMed

ABSTRACT 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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    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.
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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. · 3.53 Impact Factor
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    ABSTRACT: Single-celled microorganisms such as diatoms and coccolithophores produce inorganic microparticles with genetically controlled hierarchical nanopatterns. Besides serving as paradigms to inspire new routes for materials synthesis, biominerals themselves, particularly diatom biosilica, are increasingly utilized as templates for the synthesis of novel functional materials. Over the past decade, a large variety of methods have been established that allow not only for the attachment or coating of desired materials onto diatom biosilica but also for complete chemical conversion without altering the characteristic micro- and nanoscale morphology. Examples include the synthesis of materials for photonics (surface-enhanced Raman spectroscopy,SERS, extraordinary optical transmission, EOT), ultraresponsive and sensitive gas sensors, gas storage materials, and highly active catalysts. More recently, emerging insight into the cellular mechanisms of biosilica formation has enabled the in vivo functionalization of diatom biosilica through advanced cultivation techniques and genetic engineering. As a naturally renewable material, biominerals hold the promise of serving as an inexpensive and easily available resource for a future nanotechnology-based industry.For further resources related to this article, please visit the WIREs website.Conflict of interest: The authors have declared no conflicts of interest for this article.
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May 23, 2014