Botryococcus braunii

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Botryococcus braunii
Botryococcus braunii.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Clade: Viridiplantae
Division: Chlorophyta
Class: Trebouxiophyceae
Order: Trebouxiales
Family: Botryococcaceae
Genus: Botryococcus
Species:
B. braunii
Binomial name
Botryococcus braunii

Botryococcus braunii is a green, pyramid-shaped planktonic microalga that is of potentially great importance in the field of biotechnology. Until 2024 it was considered to have three races: A, B, and L., but it was then determined that these are three separate species. [1] Colonies are held together by a lipid biofilm matrix can be found in temperate or tropical oligotrophic lakes and estuaries, and will bloom when in the presence of elevated levels of dissolved inorganic phosphorus. The species is notable for its ability to produce high amounts of hydrocarbons, especially oils in the form of triterpenes, that are typically around 30–40% of their dry weight. [2] Compared to other green alge species it has a relatively thick cell wall that is accumulated from previous cellular divisions, making extraction of cytoplasmic components rather difficult. Much of the useful hydrocarbon oil is outside of the cell. [3]

Contents

Description

Botryococcus braunii consists of colonies of cells up to 100 μm (sometimes up to 500 μm) in diameter, composed of subcolonies sometimes connected via mucilaginous strings. Cells are grouped around the periphery of a thick matrix, forming irregularly shaped clusters. Cells, or small groups of cells, are embedded within a mucilaginous sheath which covers about two-thirds of the cell, while the tip of the cell is covered by another mucilaginous, colorless cap. The matrix is colorless, but in old colonies may be colored yellow-brown. Cells are 6–14 μm long 4–11 μm wide, obovoid, in shape with a parietal, apical, lateral or basal chloroplast and an indistinct basal pyrenoid or pyrenoid-like body; the pyrenoid may not be visible in young cells or cultures. Reproduction occurs by the formation of autospores, typically two (sometimes four) per cell. [4]

Optimal growth environment

Botryococcus braunii has been shown to grow best at a temperature of 23 °C, a light intensity of 60 W/m2, with a light period of 12 hours per day, and a salinity of 0.15 molar NaCl. [5] However, this was the results of testing with one strain, and others certainly vary to some degree. In the laboratory, B. braunii is commonly grown in cultures of Chu 13 medium.

Toxic blooms and competition

Blooms of Botryococcus braunii have been shown to be toxic to other micro-organisms and fishes. The cause of the blooms and their subsequent damage to the populations of other organisms has been studied. The exudate of Botryococcus braunii in the form of free fatty acids has been identified as the cause. A higher alkalinity changes these free fatty acids into a form which is more toxic to other species, thus causing Botryococcus braunii to become more dominant. Higher alkalinity often occurs when ashes from burned areas are washed into a body of water. While the dominance of Botryococcus braunii can be seen as damaging to the environmental diversity of a body of water, the knowledge of how it gains and maintains dominance is useful to those who intend to grow ponds of it as a fuel crop.[ citation needed ]

Biofuel applications of Botryococcus oils

The practice of farming algal species is known as algaculture. Botryococcus braunii has great potential for algaculture because of the hydrocarbons it produces, which can be chemically converted into fuels. Up to 86% of the dry weight of Botryococcus braunii can be long-chain hydrocarbons. [6] The vast majority of these hydrocarbons are botryocuccus oils: botryococcenes, alkadienes and alkatrienes. Transesterification cannot be used to make biodiesel from Botryococcus oils.[ citation needed ] This is because these oils are not vegetable oils in the common meaning, in which they are fatty acid triglycerides. While Botryococcus oils are oils of vegetable origin, they are inedible and chemically very different, being triterpenes, and lack the free oxygen atom needed for transesterification. Botryococcus oils can be used as feedstock for hydrocracking in an oil refinery to produce octane (gasoline, a.k.a. petrol), kerosene, and diesel. [7] (see vegetable oil refining). Botryococcenes are preferred over alkadienes and alkatrienes for hydrocracking as botryococcenes will likely be transformed into a fuel with a higher octane rating.

Oils

Three major races of Botryococcus braunii are known, and they are distinguished by the structure of their oils. Botryococcenes are unbranched isoprenoid triterpenes having the formula CnH2n-10. The A race produces alkadienes and alkatrienes (derivatives of fatty acids) wherein n is an odd number 23 through 31. The B race produces botryococcenes wherein n is in the range 30 through 37. Botryococcenes are the biofuels of choice for hydrocracking to gasoline-type hydrocarbons. The "L" strain makes an oil not formed by other strains of Botryococcus braunii. Within this major classification, various strains of Botryococcus will differ in the precise structure and concentrations of the constituent hydrocarbons oils. [8]

According to page 30 on Aquatic Species Program report, [9] the A-strain of Botryococcus braunii did not function well as a feedstock for lipid-based fuel production due to its slow growth (one doubling every 72 hours). However, subsequent research by Qin showed that the doubling time could be reduced to 48 hours in its optimal growth environment. [5] In view of findings by Frenz, [8] the doubling times may not be as important as the method of hydrocarbon harvest. The Aquatic Species Program also found A-strain Botryococcus braunii oil to be less than ideal, having most of its lipids as C29 to C34 aliphatic hydrocarbons, and less abundance of C18 fatty acids. This evaluation of the oils of Botryococcus braunii was done in relation to their suitability for transesterification (i.e. creating biodiesel), which was the focus of the Aquatic Species Program at the time Botryococcus braunii was evaluated. The Aquatic Species Program did not study oils of Botryococcus braunii for their suitability in hydrocracking, as some subsequent studies have done on the "B" race.

Hydrocarbon Oil Constituents of Botryococcus braunii [7]
Compound % mass
Isobotryococcene4%
Botryococcene9%
C34H5811%
C36H62 (isomer A)34%
C36H62 (isomer B)4%
C37H6420%
Other hydrocarbons18%

Extraction of oils

Compared to other green algae species, Botryococcus braunii has a relatively thick cell wall that is accumulated from previous cellular divisions, making extraction of cytoplasmic components rather difficult. Much of the useful hydrocarbon oil is outside of the cell, [3] acting as a biofilm to aggregate individual cells into colonies. The best method of separating the oils from the cells with minimal damage to the cells has long been sought. For some time, it has been known that hexane can perform this function. However, an electrical method may be cleaner and better overall. Electric fields have been applied in short pulses to extract hydrocarbons from other species of microalgae by weakening the cell walls. These pulses have been microseconds to milliseconds in length. In April 2017 it was reported [10] researchers at Kumamoto University in Japan have used shorter, nanosecond long pulses to target the extracellular matrix of Botryococcus braunii. They found the electric method to be less costly and less damaging to the cells than other methods. The Kumamoto scientists found that when the pulses are applied ten times per second, the optimal field strength was 50 kilovolts per centimeter and the optimal energy applied to be 55.6 Joules per milliliter of Botryococcus braunii matrix. Polysaccharides are also extracted from the matrix and must be separated from the oils.

Research

Due to the burgeoning interest in alternatives to fossil fuels, research on Botryococcus braunii has increased. In April 2017, Dr. Tim Devarenne of Texas A&M University (TAMU) announced the DNA sequencing of the genome of B. braunii had been completed. [11] A year earlier, in 2016, Dr. Devarenne's team at TAMU discovered the enzyme responsible for creating the Bb oil, known as lycopadiene. The enzyme is known as lycopadiene synthase, or LOS, is capable of making several types of oils. Devarenne suggested that the LOS gene might be might be implanted in other algae with faster metabolism, in order to speed up production of the oil. [12]

Potentially useful strains

This heading is a collection of strains of note because of their potential utility. Some of these strains are patented as a result of active DNA modification, while, others are from traditional selection processes.

In 1988, UC Berkeley was granted US Plant Patent 6169 for Botryococcus braunii variety Showa, developed by UC Berkeley scientist Arthur Nonomura, in the Melvin Calvin Laboratory as part of the Nobel laureate's groundbreaking interdisciplinary program for the development of renewable transport fuels. The proprietary variety was notable, says the patent application, because of its highly reproducible botryococcenes hydrocarbon content comprising 20% of the dry weight of "Showa." It is clear that Showa was borne out as the top source of hydrocarbons of its time. The patent expired in April 2008.

In May 2006, Nonomura filed an international patent application disclosing novel growth and harvesting processes for the Chlorophyta. [13] A separate patent for plants is also filed on Botryococcus braunii variety Ninsei that exhibits the feature of extracolonial secretion of it botryococcenoids that can be processed in existing gasoline refineries to transport fuels.

In August 2011, variety Enomoto was announced by IHI NeoG Algae LLC. [14] It has "...the highest yield for this fuel production over all the algae that have been discovered in the world", with a claimed monthly growth a thousand times higher than normal strains Botryococcus braunii. It is additionally said to be very robust, [15] presumably meaning it could be grown in an open environment (in ponds, instead of photobioreactors).

See also

Related Research Articles

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Biodiesel production is the process of producing the biofuel, biodiesel, through the chemical reactions of transesterification and esterification. This process renders a product (chemistry) and by-products.

<span class="mw-page-title-main">Yellow grease</span> Recycled cooking oil

Yellow grease, also termed used cooking oil (UCO), used vegetable oil (UVO), recycled vegetable oil, or waste vegetable oil (WVO), is recovered from businesses and industry that use the oil for cooking.

<span class="mw-page-title-main">Saponification value</span> Milligrams of a base required to saponify 1g of fat

Saponification value or saponification number represents the number of milligrams of potassium hydroxide (KOH) or sodium hydroxide (NaOH) required to saponify one gram of fat under the conditions specified. It is a measure of the average molecular weight of all the fatty acids present in the sample in form of triglycerides. The higher the saponification value, the lower the fatty acids average length, the lighter the mean molecular weight of triglycerides and vice versa. Practically, fats or oils with high saponification value are more suitable for soap making.

The word metagenics uses the prefix meta and the suffix gen. Literally, it means "the creation of something which creates". In the context of biotechnology, metagenics is the practice of engineering organisms to create a specific enzyme, protein, or other biochemicals from simpler starting materials. The genetic engineering of E. coli with the specific task of producing human insulin from starting amino acids is an example. E. coli has also been engineered to digest plant biomass and use it to produce hydrocarbons in order to synthesize biofuels. The applications of metagenics on E. coli also include higher alcohols, fatty-acid based chemicals and terpenes.

The Aquatic Species Program was a research program in the United States launched in 1978 by President Jimmy Carter and was funded by the United States Department of Energy, which over the course of nearly two decades looked into the production of energy using algae. Initially, the funding of the Aquatic Species Program was to develop renewable fuel for transportation. Later, the program focused on producing bio-diesel from algae. The research program was discontinued in 1996. The research staff compiled their work and conclusions into a 1998 report.

<i>Scenedesmus</i> Genus of green algae

Scenedesmus is a genus of green algae, in the class Chlorophyceae. They are colonial and non-motile. They are one of the most common components of phytoplankton in freshwater habitats worldwide.

<span class="mw-page-title-main">Selenastraceae</span> Family of algae

Selenastraceae is a family of green algae in the order Sphaeropleales. Members of this family are common components of the phytoplankton in freshwater habitats worldwide. A few species have been found in brackish and marine habitats, such as in the Baltic Sea.

<i>Botryococcus</i> Genus of algae

Botryococcus is a genus of green algae. It is a microscopic or semi-microscopic alga that is found in freshwater habitats worldwide. It consists of colonies of cells in an irregular, gelatinous matrix.

<i>Choricystis</i> Genus of algae

Choricystis is a genus of green algae in the class Trebouxiophyceae, considered a characteristic picophytoplankton in freshwater ecosystems. Choricystis, especially the type species Choricystis minor, has been proposed as an effective source of fatty acids for biofuels. Choricystis algacultures have been shown to survive on wastewater. In particular, Choricystis has been proposed as a biological water treatment system for industrial waste produced by the processing of dairy goods.

<i>Tetraspora</i> Genus of algae

Tetraspora is a genus of green algae in the family Tetrasporaceae of the order Chlamydomonadales, division Chlorophyta. Species of Tetraspora are unicellular green algae that exist in arrangements of four and consist of cells being packaged together in a gelatinous envelope that creates macroscopic colonies. These are primarily freshwater organisms, although there have been few cases where they have been found inhabiting marine environments and even contaminated water bodies. Tetraspora species can be found all around the globe, except in Antarctica. Despite the ubiquitous presence, the greatest growth of the genera's species is seen in the polar climatic zones.

<span class="mw-page-title-main">Algae fuel</span> Use of algae as a source of energy-rich oils

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<span class="mw-page-title-main">Chu 13</span>

CHU 13 medium is a culture medium used in microbiology for the growth of certain algal species, first published by S.P. Chu in 1942. It is used as growth medium for the biofuel candidate alga Botryococcus braunii.

<i>Nannochloropsis</i> Genus of algae

Nannochloropsis is a genus of algae comprising six known species. The genus in the current taxonomic classification was first termed by Hibberd (1981). The species have mostly been known from the marine environment but also occur in fresh and brackish water. All of the species are small, nonmotile spheres which do not express any distinct morphological features that can be distinguished by either light or electron microscopy. The characterisation is mostly done by rbcL gene and 18S rRNA sequence analysis.

Algae fuel in the United States, as with other countries, is under study as a source of biofuel.

<i>Nannochloropsis</i> and biofuels

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<i>Rhizopus oryzae</i> Species of fungus

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<i>Apiocystis</i> Genus of algae

Apiocystis is a genus of algae belonging to the family Tetrasporaceae. It is found attached to freshwater aquatic algae or plants. The species of this genus are found in Europe and Northern America, and are widespread but generally uncommon.

<span class="mw-page-title-main">Thraustochytrids</span> Order of eukaryotes

Thraustochytrids are single-celled saprotrophic eukaryotes (decomposers) that are widely distributed in marine ecosystems, and which secrete enzymes including, but not limited to amylases, proteases, phosphatases. They are most abundant in regions with high amounts of detritus and decaying plant material. They play an important ecological role in mangroves, where they aid in nutrient cycling by decomposing decaying matter. Additionally, they contribute significantly to the synthesis of omega-3 polyunsaturated fatty acids (PUFAs): docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), which are essential fatty acids for the growth and reproduction of crustaceans. Thraustochytrids are members of the class Labyrinthulea, a group of protists that had previously been incorrectly categorized as fungi due to their similar appearance and lifestyle. With the advent of DNA sequencing technology, labyrinthulomycetes were appropriately placed with other stramenopiles and subsequently categorized as a group of Labyrinthulomycetes.

References

  1. ↑ Boland, Devon J.; Cornejo-Corona, Ivette; Browne, Daniel R.; Murphy, Rebecca L.; Mullet, John; Okada, Shigeru; Devarenne, Timothy P. (2024). ""Reclassification of Botryococcus braunii chemical races into separate species based on a comparative genomics analysis"". "PLOS One". 19 (7).
  2. ↑ Metzger, P.; Largeau, C. (2005). "Botryococcus braunii: a rich source for hydrocarbons and related ether lipids". Applied Microbiology and Biotechnology. 66 (25): 486–96. doi:10.1007/s00253-004-1779-z. PMID   15630516. S2CID   26975859.
  3. 1 2 Wolf, Fred R.; Nonomura, Arthur M.; Bassham, James A. (1985). "Growth and Branched Hydrocarbon Production in a Strain of Botryococcus braunii (Chlorophyta)". Journal of Phycology. 21 (3): 388. doi:10.1111/j.0022-3646.1985.00388.x. S2CID   84950470.
  4. ↑ Komárek, Jiří; Marvan, Petr (1992). "Morphological Differences in Natural Populations of the Genus Botryococcus (Chlorophyceae)". Archiv für Protistenkunde. 141 (1–2): 65–100. doi:10.1016/S0003-9365(11)80049-7.
  5. 1 2 Jian Qin (2005). "Bio-Hydrocarbons from Algae: Impacts of temperature, light and salinity on algae growth" (PDF). Rural Industries Research and Development Corporation, Australia. Archived from the original (PDF) on 2011-07-15. Retrieved 2010-09-11.
  6. ↑ Algal Oil Yields – Yield Data for Oil from Algae Strains, Algae Species with High Oil Yields. Oilgae.com (2009-12-02). Retrieved on 2016-11-04.
  7. 1 2 L.W. Hillen; et al. (1982). "Hydrocracking of the Oils of Botryococcus braunii to Transport Fuels". Biotechnology and Bioengineering. 24 (1): 193–205. doi:10.1002/bit.260240116. PMID   18546110. S2CID   43310427. Archived from the original on 2012-12-10.
  8. 1 2 J. Frenz; et al. (1989). "Hydrocarbon Recovery and Biocompatibility of Solvents for Extraction from Cultures of Botryococcus braunii". Biotechnology and Bioengineering. 34 (6): 755–62. doi:10.1002/bit.260340605. PMID   18588162. S2CID   20585307.
  9. ↑ Biodiesel Production from Algae. U.S. Department of Energy Aquatic Species Program
  10. ↑ "Fast, low energy, and continuous biofuel extraction from microalgae". ScienceDaily. 2017-04-28.
  11. ↑ Browne, Daniel; Devarenne, Timothy (20 April 2017). "Draft Nuclear Genome Sequence of the Liquid Hydrocarbon–Accumulating Green Microalga Botryococcus braunii Race B (Showa)". Genome Announcements. 5 (16). doi:10.1128/genomeA.01498-17. PMC   5786678 . PMID   29371352.
  12. ↑ "Enzyme discovery leads scientists further down path to pumping oil from plants". AgriLife TODAY. Texas A&M University. 6 April 2016. Retrieved 31 May 2019.
  13. ↑ Nonomura, Arthur M. (May 5, 2006) "Methods and Compositions for Growth of Hydrocarbons in Botryococcus sp." U.S. patent 7,923,228
  14. ↑ "A new Japanese venture to pursue mass production of algae biofuel". Shimbun Denki. 2011-07-12. Archived from the original on 2011-07-13.
  15. ↑ "Formation of the Joint Venture by IHI and Neo-Morgan Laboratory for Bio-fuel production using Algae". mmdnewswire.com. Archived from the original on 2011-09-30. Retrieved 2011-08-13.
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