We have discovered an additive that stimulates the production of ethanol in Zymomonas mobilis, and induces it to secrete a number of proteins, which could be used as a platform for the delivery of cellulytic enzymes. Zymomonas is a very interesting microorganism for the production of ethanol fuel: in comparison with popular ethanol producing yeast, such as Saccharomyces cerevisiae, it grows and ferments rapidly, and has a significantly higher product rate and yield.
Yeast Strain Technology
Industrially viable strategies to optimise the release of energy from cellulosic and lignocellulosic fractions of plant material continue to constitute a focal point for biofuel research. However, consideration of the complete spectrum of plant biomass that could be used for the production of bioethanol highlights additional reservoirs of carbon-energy; plant fructans comprise one of these sources.
Yeast cells can metabolise fructose or glucose into ethanol using the well known pathways of fermentation (brewing). However the fructans found in some plant materials, i.e. fructose-polymers, cannot be digested by yeast cells without first being hydrolysised (broken down) using enzymes such as fructanase, an expensive additive to the process.
- Our invention describes a novel yeast cell with the capability to metabolise fructans into ethanol directly
- Enzyme process won't be required therefore simplifying the fermentation process, improving yield by 25% and reducing production costs
- has the ability to work with other fermenting agents such as Zymomonas Mobilis - therefore creating other potential market opportunities
Biofuels are an exciting and promising alternative to ever depleting fossil fuels. The International Energy Agency has predicted that the biofuels' share of the transportation fuel market will grow substantially from 2% to almost 30% within the next 25 years. Currently Generation 1 biofuels rely on feedstocks such as sugar cane or grain such as corn as fuel. Thus far it has been the most suitable and viable way to produce the clean burning, high-octane alternative fuel - however with an ever increasing population and limited agricultural land there is a requirement for another source of fuel for the production of ethanol.
Cellulose has long been viewed as one of the most promising long-term alternatives - a non-grain feedstock that provides the cellular structure for all plants. This includes feedstocks such as corn cobs, wheat straw, woody biomass and municipal waste, all of which are readily available. Estimates from the US Department of Energy have identified 1.3 billion tons of harvestable cellulosic biomass in the US alone, which could theoretically be used to meet more than 30% of the transportation demand within North America.
It has been suggested that the cellulosic ethanol market will be worth up to $140bn worldwide by 2020 as the US, China, the European Union and others promote biofuels as a way to reduce oil dependency and carbon emissions - an estimated reduction of 90% compared to petroleum-based fuels. Despite a very promising outlook, the challenge to overcome is the complex structure of biomass, which has presented unique technical and economic obstacles in bringing cellulosic ethanol to market. Cellulose is intrinsically more difficult to convert into ethanol than conventional starch substrates, with enzymes playing a key role in this process.