Yeast and sugar produce oils and fats, known as lipids, which can be used as substitutes for petroleum-derived products.
![Left: The starting cells have a 15% lipid content. Right: Transgenic cells with a content of almost 90% lipids. [Courtesy: University of Texas at Austin]](https://www.hayadan.org.il/images/content3/2014/01/yist-500x304.jpg "Left: The starting cells have a 15% lipid content. Right: Transgenic cells with a content of almost 90% lipids. [Courtesy: University of Texas at Austin]")
Professor Hal Alper from the Department of Chemical Engineering at the University of Texas, Houston, together with his team of researchers, succeeded in developing the original process based on innovative cells. In view of the fact that the yeast cells grow in a sugar environment, the researchers called the biofuel created within this process "a renewable version of sweet oil".
The researchers' new process succeeds in producing the highest concentration of oils and fats ever reported as part of a fermentation process, the same process by which special cells are grown that are designed to convert sugar into other useful products, such as alcohol, gases or acids. The research findings were published in the scientific journal Nature Communications on January 20 of this year.
The researchers were able to get the yeast cells to convert up to 90% of their solvent into lipids, which can then be used to produce biodiesel. "For comparison, the lipid value approaches the concentrations we know in many industrial biochemical processes," explains the lead researcher. "The resulting lipids can be taken and theoretically used to propel vehicles."
Since fatty components are building blocks for many household products, it will be possible to use this process to produce a variety of products that are produced today from petroleum or natural oils - starting with nylon, through food additives and ending with fuels. Biofuels and chemicals produced from living organisms represent a promising part of the renewable energy market. In total, the global biofuels market is expected to double its financial turnover during the next few years, from a level of 83 million dollars in 2011 to a level of 185 million dollars in 2021.
"We took the starting yeast strain (Yarrowia lipolytica) and managed to turn its cells into a factory to create oil directly from sugar," explains the lead researcher. "Our research paves the way for completely new processes for the production of renewable energy and the development of chemical sources." The biodiesel produced from the yeast cells is similar in composition to the biodiesel produced from soybean oil. The advantages of using yeast cells to produce biodiesel on a commercial level lie in the fact that the yeast cells can be grown anywhere, they do not compete for terrestrial or marine growing areas, and they are easier to genetically modify than other sources of biodiesel.
"By genetically engineering the yeast, the research team was able to produce a near-commercial-grade biocatalyst that is used to produce high levels of bio-oils during carbohydrate (sugar) fermentation," said the director of the Center for Renewable Chemicals and Fuels at the University of Florida. "This is an outstanding demonstration of the power of metabolic engineering." To date, the production of high levels of biofuels and renewable oils has been an elusive goal, but the researchers believe that their process could progress to industrial production levels.
In a large-scale engineering effort that lasted over four years, the researchers genetically modified the yeast strain Yarrowia lipolytica, both by removing and by over-expressing specific genes that affect lipid production. In addition, the researchers were able to identify the optimal growth conditions that differ from the usual conditions in similar processes. Existing methods rely on the fact that a deliberate lack of nitrogen causes the yeast cells to store fat and other substances. The researchers were able to find a mechanism to produce lipids without the use of a deliberate nitrogen deficiency. A patent has been requested for this new technology. "Our cells are not required for this nitrogen deficiency," explains the lead researcher. "This fact makes our process much more attractive from an industrial point of view." During the research, the scientists managed to raise the concentrations of the torches by 60 orders of magnitude relative to the starting point.
With a concentration of 90% lipids, the new process succeeds in producing the highest lipid content ever within the genetic engineering of yeast cells. In comparison, other yeast-based processes were only able to reach a concentration range of 80-50. At the same time, these alternative processes do not always produce the lipids directly from sugar, as is done in this innovative process. The researchers continue to look for additional ways to increase lipid concentrations and to develop new products with the help of these engineered yeasts.
Left: The starting cells have a 15% lipid content. Right: Transgenic cells with a content of almost 90% lipids.
[Courtesy: University of Texas at Austin]
2 תגובות
Filling it doesn't matter that much. Ethanol can be fermented from sugars, which is already used as biofuel today. The only difference is that ethanol is used in gasoline engines compared to biodiesel which is used in diesel engines and diesel engines are more energy efficient than gasoline engines. On the other hand, diesel engines are more expensive, more polluting and heavier (a heavy engine means a heavier vehicle that will consume more energy per kilometer driven)
In my opinion, it is worthwhile to develop ultrasonic cells that will break down cellulose (such as wood waste). After genetic engineering, it would be possible to produce oils and methanol. Perhaps this is more economical than sugar, which is used in the food industry.