Hi Douglas,Thank you for the interesting questions. I read the paper in science along with its accompanying on-line 32 page description of the genetic methodology used to create the high ethanol yeast.Before answering your questions I will go into the methodology a bit. I will mention that I taught Microbial Genetics for over twenty five years and published in both yeast and fungal genetics and molecular biology. The system developed for making high ethanol yeast is certainly genetic engineering but it is not genetic modification with transgenes. Key regulators for production of high level ethanol in the presence of high level glucose were identified in yeast. Those genes DNA sequences were altered by a process called site specific mutagenisis then reinserted into the yeast at a particular locus (the uracil gene). The regulatory genes controlled a number of genes in a metabolic network for ethanol production and most importantly ability to tolerate high levels of ethanol and glucose. The current work on such key regulators follows work on E coli ethanol production by modifying a sigma factor regulator of transcription. Douglas asked "However, we could call the effect I refer to "genome shifting",which adds an unknown, unforeseeable and uncontrollable element to the expected results. Do you agree?" I do not entirely agree. Yeast genetics are far more precise than the crude methods used in crop plants and the genes in the yeast have been precisely altered by mutations on knowingly altered DNA. Manipulating a metabolic network is new and breathe taking but could lead to unexpected toxins being produced.These will have to be checked on in the near future but since the yeast is not for very strong beer but for commercial ethanol fuel the toxins could be ignored. A former student and colleague, Inge Russel, developed a very high ethanol yeast by breeding and selection alone and her strain is presently better than the promoted higher tech system because it was bred from a commercial ethanol yeast rather than into the laboratory strains used in the high tech version.Lab yeast tend not to do all that well in commercial operations for brewing, wine making or ethanol making. The gene regulators are somewhat similar to the MADS box regulators growing popular in crop genetic manipulation that I discussed previously. However, the MADS box alterations have been transgenic while the network ethanol yeast are not. Douglas asks "To what extent is the GE yeast likely to cross with native yeasts existing in nature? Is the threat similar to that created by GE crops, or are GE yeasts likely to be less threatening? You ask an important question Douglas. My feeling this that regulators will have a hard time getting their teeth into genes that are precise;y altered within a particular organism. If unexpected toxins are produced because of metabolic network alterations then we are in real trouble. Bakers yeast is not a pathogen to anything , I believe, but it has been used as a probiotic. Killer beer is every boy's nightmare! However, the toxins should show up early and be dealt with promptly or even ignored for making fuel.However, toxic ethanol yeast in the gut would not be any fun at all. Manipulating metabolic networks is brand new but clearly here to stay. Organic farmers and the industry will soon be faced with difficult decisions about organic foods. Can genes and networks manipulated by engineered DNA code word changes within a crop be considered organic? We will soon have to decide.Let us hope the decision is ours and not the bureaucrats. Finally, many recollect that I objected to GM wine and I still do. That stuff is transgenic and should be labeled, dammit all. You cannot imagine the abuse I get from the developers of GM wine! Thanks so much for the important questions, excuse my rambling answers. sincerely,joe
Hello Joe, In relation to your important "Making the World GM-Free & Sustainable" post, I would appreciate knowing your perspective regarding the events described here: <http://www.planetark.com/avantgo/dailynewsstory.cfm?newsid=39389> My thoughts: There are aspects to this issue that are not mentioned in the article because neither Reuters nor the people at MIT involved in the creation of the GE yeast that's discussed in the article appear to be aware of certain characteristics common to all GE organisms due to the effects of the processes used to insert the foreign (or in this case, extra) gene. They apparently assume that the GE yeast referred to in the article is simply the original yeast with an added gene. However, we could call the effect I refer to "genome shifting", which adds an unknown, unforeseeable and uncontrollable element to the expected results. Do you agree? Another issue I'd like your opinion on is: To what extent is the GE yeast likely to cross with native yeasts existing in nature? Is the threat similar to that created by GE crops, or are GE yeasts likely to be less threatening? Thanks in advance for your thoughts and any orientation you can provide. Extracts: Baker's Yeast Mutant Can Boost Ethanol Output - MIT NEW YORK - Scientists have engineered baker's yeast to produce ethanol faster and more efficiently, according to a Massachusetts Institute of Technology research paper published on Thursday. The US government is urging greater use of ethanol as a way to stretch domestic motor fuel supplies and make the country less dependent on foreign oil. US demand for ethanol has also jumped as the oil industry uses it to replace gasoline additive MTBE, a suspected carcinogen banned in several states. The MIT scientists made "super" baker's yeast, by adding a gene already found in the microbe, to speed up ethanol production by about 50 percent. That could allow ethanol plants either to make more of the fuel in less time, or make more of the fuel in the same time, said Dr. Hal Alper, one of authors of the paper, published on Thursday in the international weekly science journal, "Science."... The MIT scientists engineered the baker's yeast to survive high levels of ethanol and sugars found in the processing of the fuel that kill other fermenting microbes. "The end result is that you have yeast cells that are able to survive and grow in the presence of a toxic chemical," said Alper. The yeast can survive high levels of glucose and there's no reason why it won't survive in high levels of xylose, the other main sugar found in cellulosic ethanol, he said. The research was funded by the DuPont-MIT alliance, a collaboration between the DuPont Co. and the university, the National Institutes of Health, and the US Department of Energy, and others
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