Botryococcus braunii, a green microalgae found in freshwater ponds and lakes around the world, is a promising biofuel feedstock candidate. It produces large amounts of liquid hydrocarbons that can be converted into fuels, but it also grows very slowly, so is not currently considered to be economically viable as a biofuel producer.
Scientists at Texas A&M AgriLife have been investigating how Botryococcus braunii makes liquid hydrocarbons, and in particular what genes and pathways are involved.
Dr. Tim Devarenne, AgriLife Research biochemist in College Station and lead scientist on the team said, "One of the issues with Botryococcus is that it grows very slowly. You just don't get a lot of biomass and on an economic scale that means it would not work to use this alga. It takes about a week for one Botryococcus cell to double into two cells, whereas a faster growing algae -- but one that doesn't make a lot of oil -- can double in about six hours.
"Maybe if we can transfer the genetic information to make these oils into quicker growing organisms like other algae that grow a lot quicker or a land plant that can produce large amounts of biomass, we can have them produce oil for us.
"In this study, we were interested in deciphering the biochemical pathway for making this oil, which is called lycopadiene. We discovered a very interesting gene that's called lycopaoctaene synthase, or LOS. And the enzyme encoded by the LOS gene is able to initiate the production of the oil, so we started to essentially pick apart this pathway."
The researchers discovered that the LOS enzyme is “promiscuous” – it can mix different substances to make different hydrocarbon-like products. They are using genome mining techniques to further explore the pathways involved.
Story source: Texas A&M Today, 6 Apr 2016
Journal Reference: Hem R. Thapa, Mandar T. Naik, Shigeru Okada, Kentaro Takada, István Molnár, Yuquan Xu, Timothy P. Devarenne. A squalene synthase-like enzyme initiates production of tetraterpenoid hydrocarbons in Botryococcus braunii Race L. Nature Communications, 2016; 7: 11198 DOI: 10.1038/ncomms11198