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Current advances in algae biotechnology (III)

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Current advances in algae biotechnology (III)

Editorial Current Biotechnology, 2016, Volume 5, No. 3 171
2211-551X/16 $58.00+.00 © 2016 Bentham Science Publishers
Editorial
Current Advances in Algae Biotechnology
(Part III)
Current Biotechnology” aims to provide a comprehensive and reliable source of information on
the current advances and future perspectives in key themes of biotechnology. With this objective,
Current Biotechnology published a special issue in 2015 focused on algae biotechnology. Due to the
great interest and positive feedback, we decided to release further issues on “Current Advances in
Algae Biotechnology”. The idea behind thematic ‘hot topic’ special issues is to generate maximum
impact for the published material in a particular subject area of biotechnology.
Algae biotechnology has made major progress during the past 20 years. Algae are already used as
bioreactors for producing bioproducts such as pharmaceuticals, nutraceuticals, cosmetics, pigments
and other useful chemicals, value-add products, algal-based biomaterials, feed, aquaculture and more.
In addition, many efforts are currently being undertaken to make algae competitive for production of
bioenergy and biofuels. Some algal-based strategies also meet the requirements for use in biodegradation, bioconversion,
bioremediation or other pollution solutions. A powerful driving force in algae biotechnology is the enticing option to use
genetically improved organisms. Selectable marker genes, reporter genes, constitutive and switchable promoters,
transformation techniques, and other genetic tools and methods are already available for quite a few algae species and this
molecular toolbox is becoming increasingly powerful. Moreover, omic’ technologies have been established in some algae
species and several genome sequencing projects are completed, in progress or planned. Genetically engineered algae promise a
much broader field of application than unmodified organisms or breeds, e.g., through additionally acquired physiological
capabilities and new biochemical reactions or even pathways. For some time, light-sensitive proteins from algae are even being
used in brain science and they represent a cornerstone in the emerging field of optogenetics: in transgenic animals, these algal
ion channels are able to turn individual neurons on and off instantly in a light-dependent manner. In contrast to basic research
approaches, applied research frequently takes advantage of mass-culture strategies for algae. Large scale industrial production
of bioproducts from genetically engineered, bred or unmodified algae requires state-of-the-art bioprocess engineering,
fermentation, harvesting and downstream processing.
The series of special issues on “Current Advances in Algae Biotechnology” started with my own, broad overview
introducing the theme under the title “Algae Biotechnology – Green Cell-Factories on the Rise” [1]. The first issue was
composed by this and 14 other articles, followed by the second issue with 7 articles. The third special issue on “Current
Advances in Algae Biotechnology” is also composed by 7 articles and highlights further, current advances in the field of algae
biotechnology.
This third special issue starts with a review about the challenges and prospects for algae-derived hydrogen by Ross et al.
[2]. Biofuels from algae may provide an alternative to fossil fuels. However, several obstacles still have to be overcome before
photobiological hydrogen can compete in the fuel market. Ross et al. take a wider view to examine the pros and cons of algal
biohydrogen within the broad context of algal renewable energy systems.
In the following review, Dahlin and Guarnieri give an overview about recent advances in the development of genetic tools
for eukaryotic microalgae [3]. Transgenic microalgae have become indispensable in today’s basic research on algae and there is
also a growing interest to use transgenic microalgae for economical production of bioproducts and biofuels. Therefore, the
authors also provide examples for industrially-relevant applications.
A review by Sayanova and Napier focuses on metabolic engineering of microalgae for sustainable production of omega-3
long chain polyunsaturated fatty acids [4]. In the last few years an intense research has been performed to maximize microalgal
production of omega-3 LC-PUFAs. However, several bottlenecks that limit the oil accumulation have been identified.
Sayanova and Napier describe how metabolic engineering could overcome these barriers to generate improved strains of
microalgae.
In a research article, Shi et al. present a life cycle assessment study dealing with different scenarios for the re-use of lipid-
extracted algae that are a co-product of the algae-based biofuel production [5]. Lipid-extracted algae can not only be used as a
source of energy and nutrients but also for other purposes, including as a substitute for animal feeds. The authors demonstrate
the importance of decisions made throughout the full value chain of a product in determining the environmental impact of a
product, given the regulatory pressure to develop low-carbon fuels.
Undurraga and Poirrier analyze the cultivation of microalgae in continuous culture photobioreactors operated as light-
limited chemostats to attain a high level of microalgae productivity [6]. Even if continuous culture is underused in the area it is
a method with significant benefits. The authors present the fundamental concepts of this operation method and they apply them
in continuous culture photobioreactors.
172 Current Biotechnology, 2016, Volume 5, No. 3 Editorial
Rorrer et al. evaluate the potential of a diatom-based photosynthetic biorefinery concept for production of biofuels and
valued co-products [7]. More specifically, the authors use a two-stage cultivation process to induce high levels of lipid and
chitin production in the centric diatom Cyclotella. The co-product chitin, its monomer N-acetyl glucosamine and the derivative
glucosamine are suitable for nutraceutical and biomedical applications. Rorrer et al. discuss the yields and productivity of their
concept.
Santos et al. deal with aeration energy requirements in microalgal heterotrophic bioreactors applied to agroindustrial
wastewater treatment [8]. The experimental data allow estimating the aeration energy requirements and the net energy ratio of
the system. The established operational conditions resulted in a positive energy balance.
We hope that you enjoy this third special issue on “Current Advances in Algae Biotechnology”, that you will benefit from
the insights it provides and that you think about own (further) contributions that you perhaps can make to this exciting field.
REFERENCES
[1] Hallmann, A. Algae biotechnology – Green cell-factories on the rise. Curr Biotechnol 2015; 4(4): 389-415.
[2] Ross, I. L., Oey, M., Stephens, E., Hankamer, B. Prospects for photobiological hydrogen as a renewable energy. Curr Biotechnol 2016; 5(3): 173-91.
[3] Dahlin, L. R., Guarnieri, M. T. Recent advances in algal genetic tool development. Curr Biotechnol 2016; 5(3): 192-97.
[4] Sayanova, O., Napier, J. A. Metabolic engineering of microalgae for sustainable production of omega-3 long chain polyunsaturated fatty acids. Curr
Biotechnol 2016; 5(3): 198-212.
[5] Shi, R., Handler, R. M., Shonnard, D. R. Life-cycle assessment of algae renewable diesel: Influence of alternative uses for lipid-extracted algae. Curr
Biotechnol 2016; 5(3): 213-26.
[6] Undurraga, D., Poirrier, P. Continuous microalgae culture: Operation of light-limited chemostats. Curr Biotechnol 2016; 5(3): 227-36.
[7] Rorrer, G. L., Torres, J. A., Durst, R., Kelly, C., Gale, D., Maddux, B., Ozkan, A. The potential of a diatom-based photosynthetic biorefinery for
biofuels and valued co-products. Curr Biotechnol 2016; 5(3): 237-48.
[8] Santos, A. M., Deprá, M. C., Santos, A. M., Zepka, L., Q., Jacob-Lopes, E. Aeration energy requirements in microalgal heterotrophic bioreactors
applied to agroindustrial wastewater treatment. Curr Biotechnol 2016; 5(3): 249-54.
Armin Hallmann
(Guest Editor)
Department of Cellular and Developmental Biology of Plants
University of Bielefeld
Bielefeld
Germany
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
BACKGROUND: Recent years have witnessed fast growing developments in algae biotechnology. There is a broad range of diversity in algae biotechnology research and industry. METHODS: A general literature review on all aspects of algae biotechnology was conducted. The main findings are summarized and the relevance for further research and biotechnological applications is discussed. RESULTS: Algae are used as bioreactors for producing bioproducts such as pharmaceuticals, nutraceuticals, cosmetics, pigments and other useful chemicals, algal-based biomaterials, feed and more. Light-sensitive proteins from algae represent a cornerstone in the emerging field of optogenetics. In addition, many efforts are currently being undertaken to make algae competitive for production of bioenergy and biofuels, aiming to evolve into integrated biorefineries. Applied research approaches require mass-culture strategies for algae including bioprocess engineering, fermentation, harvesting, and downstream processing. Some algal-based strategies also meet the requirements for use in bioremediation, biodegradation or other environmental applications. A powerful driving force in algae biotechnology is the enticing option to use genetically improved organisms. Selectable marker genes, reporter genes, promoters, transformation techniques and other genetic tools and methods are already available for several few algae species and this molecular toolbox is becoming increasingly powerful. Quite a few algae genome sequencing projects are completed and others are in progress or planned facilitating genetic engineering. Transgenic algae promise a much broader field of application than unmodified organisms or breeds, e.g., through additionally acquired physiological capabilities and new biochemical reactions, and open the door to improved algal bioproducts and molecular farming. CONCLUSION: Algae are an extremely diverse group of organisms and therefore provide a substantial reservoir of biomolecules, cellular functions and physiological characteristics. Insight into cellular and molecular mechanisms and the opportunity to use algae as green cell-factories have resulted in a constantly growing economic importance of algae technologies and products.
Article
BACKGROUND: Hydrogen is a clean, versatile fuel and energy carrier which can be produced by a range of renewable technologies for combustion, use in fuel cells, or as a manufacturing feedstock. Despite its attraction and significant technological innovation, commercial feasibility of photobiological hydrogen processes is far from demonstrated. OBJECTIVE: This review examines direct photobiological biohydrogen systems, with a particular focus on the main obstacles that must be overcome to deliver commercially viable, net energy positive systems. As part of this process the interactions between future photobiological biohydrogen systems and other parts of a renewable energy economy are examined to analyse potential technology integration paths. RESULTS: The primary driver for renewably produced hydrogen is the potential for CO 2 emissions reductions. Renewable hydrogen is largely solar driven, either directly (e.g. natural photosynthesis, or bio-inspired devices) or indirectly (e.g. fermentation, electrical hydrolysis). A significant market for hydrogen already exists and is supported by extensive infrastructure providing significant opportunities for emerging renewable hydrogen streams. Several key physiological obstacles to efficient photobiohydrogen production have already been overcome, with oxygen tolerance as the most significant remaining problem. CONCLUSIONS: A much deeper understanding of photosynthetic biology is required before existing knowledge can be integrated with real world systems. Cross-fertilisation between engineering and biology represents the best path forward for implementation as a robust biotechnology.
Prospects for photobiological hydrogen as a renewable energy Recent advances in algal genetic tool development
  • I L Ross
  • M Oey
  • E Stephens
  • B Hankamer
  • L R Dahlin
  • M T Guarnieri
Ross, I. L., Oey, M., Stephens, E., Hankamer, B. Prospects for photobiological hydrogen as a renewable energy. Curr Biotechnol 2016; 5(3): 173-91. [3] Dahlin, L. R., Guarnieri, M. T. Recent advances in algal genetic tool development. Curr Biotechnol 2016; 5(3): 192-97. [4]