Botryococcus braunii
| Botryococcus braunii | |
|---|---|
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| Botryococcus braunii | |
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Chlorophyta |
| Class: | Trebouxiophyceae |
| Order: | incertae sedis |
| Family: | Botryococcaceae |
| Genus: | Botryococcus |
| Species: | B. braunii |
| Binomial name | |
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Botryococcus braunii Kützing |
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Botryococcus braunii (Bb) is a green, pyramid-shaped planktonic microalga that is of potentially great importance in the field of biotechnology. Colonies 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. Compared to other green algae species it has a relatively thick cell wall that is accumulated from previous cellular divisions; making extraction of cytoplasmic components rather difficult. Fortunately, much of the useful hydrocarbon oil is outside of the cell.
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. 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 .
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 Bb 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 Bb to become more dominant. Higher alkalinity often occurs when ashes from burned areas are washed into a body of water. While the dominance of Bb can be seen as damaging to the environmental diversity of a body of water, the knowledge of how Bb can gain and maintain dominance is useful to those who intend to grow ponds of it as a fuel crop.
The practice of farming cultivating 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. The vast majority of these hydrocarbons are botryocuccus oils: botryococcenes, alkadienes and alkatrienes. Transesterification can NOT be used to make biodiesel from Botryococcus oils. 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. (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.
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Wikipedia