This project is carried out in the group of Systems Biology
Increased petroleum prices along with concerns about carbon dioxide emission and the lack of
sustainability of fossil fuels have been motivating the development and production of biofuels.
As about 80% of crude oil is being used for liquid transportation fuels it is quite obvious that
there is a particular focus on how one can develop biotech processes for the production of liquid
The currently dominating biofuel is bioethanol produced via yeast fermentation. We are developing
new yeast strains that instead of ethanol can produce a range of alternative biofuels with properties
close to diesel and jet fuels. In addition, these yeast strains need to be optimized to grow on feed
stocks that do not compete with food production.
The lack of sustainability of fossil fuels is one of the main drivers to develop new biofuels, especially
liquid transportation fuels. The major biofuel produced today is bioethanol, which is generated
via fermentation using baker´s yeast. The sugars required as raw material for the fermentation
process are currently typically derived from sugar cane (Brazil) and maize (USA). Bioethanol is used
as additive to gasoline, but does not possess the suitable properties to be used in diesel engines.
Biodiesel on the other hand is usually derived from plant oils (such as rape seed, soybean or palm
oil), which is chemically modified with an alcohol (e.g. methanol) to form long chain fatty acid alkyl
esters. These can directly be used in diesel engines. The current production processes for bioethanol
and biodiesel both, however, have the disadvantage that large areas of arable land are required,
which competes with the cultivation of food crops.
We are therefore aiming at developing new processes for the production of diesel-like fuels based on
yeast fermentation, which will compete to a much lower extend or not at all with food production.
This will be achieved by using cellulosic biomass, for example agricultural residues as raw material.
Being used for bioethanol production, yeast has proven to serve as a robust organism suitable
for fermentations at very large scale as required in the biofuel industry. In contrast to ethanol
however, yeast does not naturally produce diesel-like fuels. In addition, it does not grow efficiently
on cellulosic biomass. To address this, biochemical pathways that enable growth on cellulosic
biomass and the production of compounds with properties similar to diesel and jet fuels are being
transferred from other organisms to yeast. Subsequently, additional extensive engineering efforts
accompanied by computational modeling are required to rewire the yeast metabolism for efficient