Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal




НазваниеTransportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal
Дата конвертации15.02.2013
Размер21.3 Kb.
ТипДокументы
Algae as biofuels

From 1978 to 1996 the US Department of Energy’s office of fuels development funded the Aquatic Species Program (ASP) whose aim was the development of transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal biofuels. Algae are of particular interest as they are more productive per acre than conventional terrestrial oil crops, and can be grown in non-agricultural lands, thus not directly competing with food crops (Groom et al. 2008). The ASP collected and studied over 3000 strains of algae, covering a wide diversity of taxa and environments. The research summarized in the ASP final report (Sheehan et al. 1998) lays the groundwork for a more focused biological approach to algal biofuels research.

After 3000 strains of algae were studied, the ASP final report concluded that a group of single-celled micro-algae known as diatoms were one, if not the best, choice for continued biofuels research (Sheehan et al. 1998 p.248). This conclusion was based on the diatoms’ high productivity, ability to grow in large-scale culture, and high cellular oil accumulation, accounting for 40-60% of the cell’s mass in some taxa.

With general screening performed, the top recommendation of the ASP final report for future biofuels research was to “put less emphasis on outdoor field demonstrations and more on basic biology” (Sheehan et al. 1998 p.20). This lack of understanding of the fundamentals of microalgal biology remains prevalent within current algal biofuels research, creating profound and inherent inefficiencies resulting from the use of only a small number of existing strains and the lack of optimization for each individual application. Much of the current biofuels research continues to be based on the screening of only a handful of individual algal taxa (from the naturally occurring wide variety of evolutionary lineages) in an attempt to find the best strain for biofuel production. This approach is thus based on a “silver bullet” model, where it is assumed that there is an ideal algal biofuel strain that can be manipulated to meet a wide range of needs and conditions required. Although still prevalent, this model has been largely rejected by the research performed during the ASP (Sheehan et al. 1998 p.14), which concluded that the best, most desirable algal strains were likely to be rather different for each growing site, depending on the specific local growth conditions (temperature, salinity, pH, etc.).

A common theme in biology is determining if factors responsible for a particular trait or outcome are based on Nature (inherent evolutionary history) or Nurture (external factors). As opposed to only the laboratory manipulation of a few individual cultured algal strains (Nurture only), a more efficient and useful strategy would be a systematic, in-depth investigation of a whole taxonomic group of algae with not only a wide geographic and ecological distribution, but also high lipid production (Nature + Nurture). By developing an evolutionary tree for this group of algae, and overlaying this with algal oil levels and optimal environmental growth conditions, a predictive tool or “roadmap” for the flexible selection of appropriate algal strains for a wide variety of future applications can be produced.

The diatom genus Amphora is particularly well suited for this type of study. Of the diatom taxa examined to date, Amphora strains accumulate some of the highest levels of oils/fats during nutrient (silica) limitation (see below) and during the non-limiting exponential growth phase (Sheehan et al. 1998 p.25-26). Along with high lipid levels, Amphora strains exhibit high productivity reproducing on average 2.81 times /day (Sheehan et al. 1998 p.24), putting them on par with the fastest-growing green algae and cyanobacteria. Amphora species are found in marine, estuarine, and fresh waters from the arctic to the tropics. The unique combination of fast growth rate, high lipid levels, and broad ecological habitats to which they are adapted makes these species ideal for this type of investigation.

Although shown to exhibit favorable biofuels characteristics, only 29 strains representing 2 species within a single sub-genus have thus far been closely investigated. When compared to the nine sub-genera and over 1400 named taxa (Fourtanier and Kociolek 2007), the few already characterized species represent only tiny fraction of this potentially important group.


Methods

Collect 2-3 exemplars from each of the 9 subgroups of Amphora, from marine, estuarine and freshwater habitats in North America. [Florida, Gulf Coast, West Coast of USA, Great Lakes and Colorado], representing a wide range of salinity, pH, temperature and nutrients.

From each locale, two collections of live material will be made along with geographic and environmental data; one sample will remain alive, the other will be field-preserved. Calibrated probes will be used to determine temperature, light intensity, salinity, pH at the time of collection. Other key aspects of water chemistry (total content of nitrogen and phosphorus) will also be evaluated via field-based methods. Collections will be returned to the lab for further analysis.


Estimating Oil Production from Field and Culture Collections

A part of each preserved sample will be cleaned and permanent slides made for light microscopy (LM) and material will be air-dried onto cover-slips for scanning electron microscopy (SEM) investigation. For LM of fixed and stained materials, we will identify species, take pictures of the cells, and determine both overall cell volume and the volume of lipid present in each cell, which should allow us to assess the average volume of oil per cell and relate that to the environmental conditions in which each was found. This will allow us to determine both within-species and across-species variation and differences.

Live cells will be cultured in a variety of media (we are currently using WC media [Guillard 1983], and have had success with growing members of the subgenus Halamphora. We will evaluate oil production in the cultured cells by the same technique described for the fixed cells. The ability to accurately quantify algal oil content is important, but not trivial. We will therefore validate and calibrate our cell and oil volume calculations with a technique (based on rapid optical screening of algal oil content from the fluorescence signal of the oil-marking fluorescent dye Nile Red; cf. Cooksey et al. 1987) recently adopted and further developed at CU-Boulder by Jimenez in collaboration with Demmig-Adams and Adams. The work proposed here will allow Kociolek to interface in a synergistic way with work in the Jimenez, Demmig-Adams and Adams, and Lewis labs, to better calibrate our estimates of the production of oil in Amphora species, and to likewise leverage this work in support of work on a recently funded NSF EAGER grant (Demmig-Adams, Jimenez, Adams & Lewis). The proposed work will initiate a new collaboration between Kociolek and these other algal researchers at CU-Boulder and will thereby provide the basis for future major joint grant proposals from this group.

From live samples from each locale, we will isolate and culture all species present. In the cultures, we will vary several key environmental parameters, including temperature, light:dark cycle, salinity and pH, as variables known to affect oil production. Amphora is particularly attractive since it produces maximal to near maximal levels of oil during rapid (log-phase) growth, rather than only in response to productivity-inhibiting stresses as is the case for most other algae currently investigated for oil production.


Environmental Tolerances and Preferences

We will also count 600 valves per sample and determine the relative abundance for each Amphora species investigated. This will provide us with information on the tolerances (occurrence) and preferences (greatest relative abundances) for each species across the ecological spectra we sample. This will allow us to determine the range of natural environmental conditions in which each species was found, and the conditions in which it was best represented.


Developing the Evolutionary Roadmap

From the species derived from live cultures we will construct a multi-gene phylogenetic tree. A multi-gene approach has yielded excellent results for a wide phylogenetic spectrum of diatom taxa (Alverson et al. 2007; Sorhannus 2004, 2007; Sims et al. 2006), as data from several genes is more likely to yield an accurate tree than data from a single gene.

The “cleaned” material will be used for LM and SEM observations of the glass cell wall features to construct evolutionary trees, a technique that has been done successfully with other diatom groups Stephanodiscus, (Theriot et al. 1987) Meridion, Diatoma,(Williams 1985, 1990) Gomphonema, Gomphoneis, Cymbella, (Kociolek and Stoermer 1988, 1989, 2003) and Surirella (Ruck and Kociolek 2004).

The concomitant use of form (morphology) and genetic heritage (molecular genetics) is the modern gold standard for establishing the evolutionary descent of a group of organisms and that this objective is thus a centerpiece of the proposal. We will therefore use a variety of computer phylogenetic programs to develop both molecular-based and morphology-derived trees, and then use their overlap/congruence (e.g. Edgar & Theriot 2004) to develop a single “roadmap” of evolutionary descent for the exemplars for Amphora, based on a diversity of data from both morphology and molecules/genes.


Integrating Evolutionary History, Environmental and Oil Production: Initial Results and Innovation

Upon the above-described tree, we will map algal taxa that have (i) the principal propensity to produce the greatest amount of oil and (ii) actually do so under both natural and culture conditions. “Start with what works in the field. Select strains that work well at the specific site where the technology is to be used. These native strains are the most likely to be successful.” (Sheehan et al. 1998 p. 21)

Results are expected to identify lineage(s) that have both the genetic background (genomic basis) for high oil production (Nature) and the ability to produce its highest levels under actual culture conditions (Nurture). Adding to the newly developed evolutionary roadmap the conditions, in nature and in culture, will also allow for the refinement of culture conditions, estimate yields and possible economic models for future development.

The proposed approach also offers a new way to estimate oil production (in terms of oil volume) than has traditionally been done (% of algal body weight). Past approaches with diatoms are likely to have underestimated the amount of oil, since the glass cell walls of diatoms add significantly to the weight of these organisms (e.g. 60% of the dry weight of the diatom species Aulacoseira italica is silica; Lund 1965).

Prospects for Future Research Funding

NSF

The results of the proposed study will be used to develop proposals to NSF for (i) a broader phylogenetic study of the position of the sub-group group of algae on which we will focus here in the overall scheme of diatoms as well as (ii) the use of ecological characters and the biogeography of microbes in the establishment of evolutionary descent (phylogenetic inference) and (iii) including many more taxa in the evaluation.

Industry

We expect to be able to provide industry with a new way of estimating oil production of algae, in volumetric terms instead of by a percentage of cell weight or mass. Scaling up the production of species that meet a variety of conditions (oil production, specific ecological tolerances and conditions under which oil is produced) and possible areas for future exploration of species (based on the predictive roadmap) will also be elements of future funding potential.

References

Alverson, A.J., Jansen, R.K., and Theriot, E.C. (2007) Bridging the Rubicon: Phylogenetic analysis reveals repeated colonizations of marine and fresh waters by thalassiosiroid diatoms. Mol. Phyl. Evol. 45:193-210.

Cooksey, K.E., Guckert, J.B., Williams, S.A., Callis, P.R. 1987. Fluorometric determination of the neutral lipid content of microalgal cells using Nile Red. Journal of Microbiological Methods. 6:333-345.


Dempster, T.A. & Sommerfeld, M.R. 1998. Effects of environmental conditions on growth and lipid accumulation in Nitzschia communis (Bacillariophyceae). Journal of Phycology. 34:712-721.


Edgar, S.M., and Theriot, E.C. 2004. Phylogeny of Aulacoseira (Bacillariophyta) based on morphology and molecules. J. Phycol. 40:772-788.

Groom MJ, Gray EM, Townsend PA (2008) Biofuels and biodiversity: Principles for creating better policies for biofuel production. Conservation Biology 22: 602-609

Guillard, R.R.L. 1983. Culture of phytoplankton for feeding marine invertebrates. In Berg. C.J. [Ed.] Culture of Marine Invertebrates. Hutchinson Ross Publ. Co., New York, pp. 108-132.


Fourtanier , E & Kociolek, JP. Catalogue of Diatom Names, California Academy of Sciences, On-line

Version.Available online at http://www.calacademy.org/research/diatoms/names/index.asp.


Kociolek, J.P., and Stoermer, E.F. 1988. A preliminary investigation of the phylogenetic relationships among the freshwater apical pore field-bearing cymbelloid and gomphonemoid diatoms (Bacillariophyceae). J. Phycol. 24:377-385.

Kociolek, J.P., and Stoermer, E.F. 1989. Phylogenetic relationships and evolutionary history of the diatom genus Gomphoneis. Phycologia 28:438-454.

Kociolek, J.P., and Stoermer, E.F. 1993. Freshwater gomphonemoid diatom phylogeny: Preliminary results. Hydrobiologia 269-270:31-38.

Ruck, E.C., and Kociolek, P. 2004. Preliminary phylogeny of the family Surirellaceae. Bibliotheca Diatomologica 50:1-236.

Sheehan, J., Dunahay, T., Benemann, J., Roessler, P., 1998. A Look Back at the US

Department of Energy’s Aquatic Species Program: Biodiesel from Algae Golden.

National Renewable Energy Laboratory, Colorado, TP-580-24190.

Sims, P.A., Mann, D.G., and Medlin, L.K. (2006) Evolution of the diatoms: insights from fossil, biological and molecular data. Phycologia 45:361-402.

Singh, A., Nigam, P.S., Murphy,.J.D., 2010. Mechanism and challenges in commercialism of algal biofuels. Bioresource Technology. 102:26-34.

Sorhannus, U. 2004. Diatom phylogenetics inferred based on direct optimization of nuclear-encoded SSU rRNA sequences. Cladistics 20:487-497.

Sorhannus, U. 2007. A nuclear-encoded small-subunit ribosomal RNA timescale for diatom evolution. Mar. Micropal. 65:1-12.

Theriot, E., Stoermer, E., and Håkansson, H. 1987. Taxonomic interpretation of the rimoportula of freshwater genera in the centric diatom family Thalassiosiraceae. Diatom Res. 2:251-265.

Williams, D.M. 1985. Morphology, taxonomy and inter-relationships of the ribbed araphid diatoms from the genera Diatoma and Meridion (Diatomaceae: Bacillariophyta). Biblio. Diatom. 8:1-228.

Williams, D.M. 1990. Cladistic analysis of some freshwater araphid diatoms (Bacillariophyta) with particular reference to Diatoma and Meridion. Plant Syst. Evol. 171:89-97.

Добавить в свой блог или на сайт

Похожие:

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconFact: there is a finite amount of coal and oil in the earth. Fact: the majority of our energy comes from coal and oil. Fact: we need to find a new source of

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconBiomass and Other Renewable Energy Options to Meet Energy and Development Needs in Poor Nations

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconRecent trends in emerging transportation fuels and energy consumption

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconNeg Uniqueness Global Oil Demand High

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconNigeria Oil da 1nc shell A. Uniqueness: Nigeria on the brink now- future stability is dependent on oil politics

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconChanging properties of the asphalt- and oil-derived components in asphalt-oil paints prepared according to 19

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconBackstopping da 1nc shell High oil prices are driving investment and growth in renewables

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconMlps have only been available to investors in energy portfolios for oil, natural gas, coal extraction, and pipeline projects

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconThe strategies of brics’ national oil companies for energy security : joint ventures bargaining and vertical integration

Transportation fuels from high-oil-producing algae. New emphasis on renewable energy options and foreign oil independence has led to renewed interest in algal iconТоо «Oil Services Company» г. Актау, мкр. 23 18. 09. 2012 года
Тендерная комиссия, созданная для проведения открытого тендера по закупке товаров (далее — Тендер) на основании приказа директора...


Разместите кнопку на своём сайте:
lib.convdocs.org


База данных защищена авторским правом ©lib.convdocs.org 2012
обратиться к администрации
lib.convdocs.org
Главная страница