Biodiesel from sawdust
Man has been using vegetable and animal fats for more than a hundred years to produce fuel and various chemical products: surfactants, solvents and lubricants. The growing needs of the population and limited resources have caused not only the rise in prices for natural raw materials, but also the emergence of a number of serious environmental problems. In this regard, experts believe that a more expedient alternative from all points of view is the production of fuel and other chemicals necessary for humans by bacterial processing of renewable raw materials, for example, plant biomass. However, the technologies currently available do not provide sufficient profitability of commercial production of such fuel. One of the actively developed approaches to solving this problem is the use of fatty acids – energy-rich molecules synthesized by living cells.
Working under the leadership of the luminary of synthetic biology Jay Keasling, scientists from the Joint Institute of Bioenergy (JBEI), founded by the US Department of Energy and uniting scientists from several world-renowned laboratories, the main of which is the Lawrence Berkeley National Laboratory (LBNL), and the private industrial biotechnology company LS9 (San Francisco) a strain of E. coli (Escherichia coli) capable of producing high-quality diesel fuel and other valuable chemical compounds from untreated plant biomass has been created.
The results of the work were published in the journal Nature on January 28 in the article "Microbial Production of Fatty Acid-Derived Fuels and Chemicals from Plant Biomass".
Usually, E. coli does not waste energy on the production of excess fat. The fatty acids synthesized by it bind to a carrier protein, the accumulation of which suppresses the production of fatty acids. With the help of genetic engineering methods, the developers first disconnected this feedback loop, after which they "weaned" the E. coli to use fatty acids for energy. As a result, they obtained a microorganism that produces an excessive amount of fatty acids, and removes these unnecessary substances into the external environment, which facilitates the production of fuel in the bioreactor.
After that, using the methods of synthetic biology, the authors built into the genome of E. coli genes that provide the ability to produce substances with desired properties directly from simple carbohydrates: fatty acid esters (biodiesel), alcohols and paraffins. The final stage was the creation of a strain of bacteria capable of synthesizing hemicellulases – enzymes that break down the complex carbohydrate hemicellulose, which is the main component of biomass and, accordingly, the main depot of chemical energy preserved in the shells of plant cells.
The resulting strain of E. coli is able to produce fuel and other chemicals directly from biomass, unsuitable even for pet food. Now, for the production of biofuels, such biomass is subjected to expensive enzymatic treatment, which ensures the release of simple carbohydrates.
On the left is a group of E. coli secreting lipid droplets containing biodiesel, fatty acids and alcohols;
on the right is the process of releasing synthesized substances into the external environment.
Currently, the authors are working on maximizing the efficiency and speed of bacteria. They are confident that their development will greatly facilitate and reduce the cost of biofuel production and, thus, will help in solving one of the global problems of our time.
Evgenia Ryabtseva, Alexander Chubenko
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Lawrence Berkeley National Laboratory: Microbes Produce Fuels Directly from Biomas.
01.02.2010