Yeast and biofuels
Biofuels are sources of energy produced from crops. They are designed as a solution to the environmental and economic problems incurred by fossil fuel. They have attracted growing interest from researchers since the 1970s. This was when Brazil envisaged developing new sources of sustainable energy on its own territory with the aim of becoming the leading producer of alcohol fuel, on the same footing as the United States.
Currently, 90% of conventional car engines run on petrol while only 10% on alcohol. Yet it is not impossible to see our cars driven exclusively by alcohol in the near future. A first conclusive attempt was made in 1860!
But what does yeast have to do with all this?
A microscopic factory
Yeast is a genuine little factory, capable of transforming plant sugars into fuel. The magic works during an anaerobic process (in the absence of air) called fermentation. Under the action of yeast enzymes, sugars (in particular glucose) contained in cellulose or starch are transformed into ethanol.
The challenges facing research
The aim of this project is to produce second-generation ethanol on an industrial scale. First-generation biofuels were obtained using natural food crops, amylased plants (grains, cereals, potatoes, manioc, etc.) and sugar plants (beet, sugar cane). Second-generation biofuels will be obtained from more diversified resources, taking cellulose from plant fibres not grown for human food consumption, e.g. wood, the non-food parts of plants (stems, leaves, etc.) or plant waste.
The challenge now facing research is twofold: increasing yeast’s resistance to alcohol and extending yeast’s assimilation capacity to types of sugar other than glucose, like pentoses. These pentoses are contained in plant fibres, making up 30% as opposed to 70% for glucose.
Rising to this challenge will increase the range of renewable energy sources available and hence promote sustainable development. A broader alternative to fossil fuels may be proposed, especially in the transport sector and to appreciably reduce greenhouse gases.