Background
Currently, most ethanol production uses strains of S. cerevisiae that are highly adapted to the industrial process of converting food feedstocks such as corn starch and cane sugar into ethanol. These yeast strains combine efficient conversion of food sugars into ethanol, with other important industrial characteristics such as low nutrient requirements, ethanol resistance, tolerance to low pH, and general robustness.Today's ethanol industry is based on "food" and has limitations
Today, ethanol is by far the dominant alternative transport fuel because of several features including its ease of production, its competitive price, and its compatibility with the existing transport infrastructure. However, the corn and sugar feed-stocks used today, whilst underpinning ethanol production of close to 20 billion gallons per year, are not abundant enough to replace more than a modest portion of the estimated one trillion gallons of liquid fossil fuels used world wide each year. In addition to limitations in quantity, the current feed-stocks are relatively expensive since they have high value as human and animal food. Thus the current ethanol manufacturing process cannot provide enough competitively priced ethanol to replace enough petroleum fuels on a global scale to solve the multiple problems of peaking oil supply, high prices, greenhouse gas effects and the flow on effect on food prices.
Next generation industry needs to be based on abundant "waste" biomass
One alternative source of renewable substrates for large scale bio-ethanol production is the plant biomass termed lignocellulose. Relative to traditional feedstocks, lignocellulose is in plentiful supply at low cost. Sources include corn stover, sugar cane bagasse, wheat and rice straw, forestry wastes, waste paper, and other plant based wastes. Their usage would be relatively low cost because they are low value carbohydrate/lignin waste by-products from other industries such as agriculture and are not used as human food.
New strains of yeast needed to grow on "wood" sugars
To convert lignocellulose (waste bio-mass) to ethanol, it must be first broken down into its component sugars, and the sugars must then be fermented or converted into something more valuable/useful. The breakdown, or de-polymerization, of lignocellulose can be achieved through either chemical (e.g. acid hydrolysis) or enzymatic means. Currently, considerable effort is being directed to the enzymatic approach, as this is a clean, efficient and potentially cost effective method. The sugars generated from lignocellulose are a mixture of hexoses (e.g. glucose), and pentoses (e.g. xylose and arabinose).
Lack of industrial strains that can also grow on wood sugars is a problem
The hexose sugars can be readily fermented into ethanol using industrial strains of the yeast Saccharomyces cerevisiae - as is done today. However, yeast varieties of the genus Saccharomyces have not been found that can either grow on or ferment pentose sugars, such as the most common pentose sugar xylose. In addition, despite extensive searching, no other organisms have been found that combine all the industrially relevant characteristics required for cost-effective fermentation of xylose into ethanol. The inability of current organisms to grow on or ferment pentoses such as xylose and arabinose into ethanol represents a major barrier to the lignocellulose-to-ethanol industry.
Most researchers have been relying on genetic engineering
Since scientific dogma states that Saccharomyces cannot grow on xylose, a key goal for yeast researchers has been to use genetic engineering to develop strains of S. cerevisiae that can ferment xylose into ethanol. In most of these strategies, genes from other organisms have been introduced into S. cerevisiae enabling it to ferment xylose, albeit initially at relatively low rates. To improve these rates further, pure genetic engineering approaches have been used with some success. In addition, some groups have recently started supplementing pure genetic engineering approaches with evolutionary approaches to improve the xylose fermentation rates in genetically engineered organisms.
Engineered yeast or bacteria yet to be optimised
Despite the progress made through genetic engineering, organisms are yet to emerge that are used in the commercial production of ethanol at an economic cost utilising the sugar streams derived from lignocellulose sources. One challenge facing the pure genetic engineering approach is the difficulty in optimising the genes in yeast that govern the multiple traits associated with efficient industrial and large scale application. Since fermentation is a core metabolic function, this necessarily involves many of the 6,000 genes in the yeast genome.
Engineering of bacteria and yeast is problematic
Manipulating the genes of bacteria or yeast in a systematic way by using genetic engineering techniques can offer a considerable insight to the mechanisms involved in efficient ethanol production under industrial conditions. However, to use this approach to generate industrially useful strains is challenging because of the potentially large number of genes that need to be manipulated and optimised in concert: most of which are poorly understood at the moment.
Yeast seems to be a superior organism to bacteria - yeast used today
Yeast has a number of inherent advantages over bacteria as an organism to be used in an industrial process. The strongest indicator that yeast is superior to bacteria is that yeast is currently used in all commercial ethanol plants around the world.
The Microbiogen breeding program is just adding to the already superior traits of yeast.
Any GMO solution also faces environmental issues
A second challenge facing all recombinant DNA technology approaches is that once genetic engineering is used to modify yeast or any other microbe, the organism's release into the environment is subject to many regulatory constraints. These regulatory constraints (e.g. need for containment of GM organisms) have the potential to increase the capital and running costs of producing lignocellulose-derived ethanol.
Strains developed by MBG are non-GMO
Microbiogen is a company with strong genetic engineering skills and believes that this technology is important and can be highly beneficial. However, for the purpose of developing new strains for the next generation ethanol plant, Microbiogen believes that a non-GMO approach has a number of significant advantages resulting in more ethanol being produced and solving, to a large degree, the "food versus fuel" issue. The strains developed by Microbiogen do not need to be contained and excess yeast biomass generated from the production of ethanol could potentially be sold as a valuable feed product rather than destroyed.