We will hear all kinds of people who know zero science interpret this lab result as a "breakthrough," and carry on with the usual corn lobby mysticism. At the same time we have the Luddites over at Greenpeace - who also know zero science - in a tizzy over how purely evil genetic engineering is.
This would of course be fun to watch, like co-ed mud wrestling maybe, but the most likely outcome of this deal will be the usual nothing at all.
Of course, I'm not familiar with the particulars of Greenpeace stupidity with respect to their gene related paranoia, but I'm sure it's of similar quality to their anti-nuclear paranoia. Also I don't happen to know all that much about genetic engineering. The technique used to "engineer" this strain is called "Global Transcription Machinery Engineering" which works by interfering, via PCR, with the transcription of genes, creating a library of mutants, but I'm certainly not familiar with what the details might mean.
To me it looks like an interesting case of directed evolution, and I have no problem with it, but I'm certainly not stupid enough to understand what Greenpeace might think of it.
From the paper (Science 8 December 2006 314: 1565-1568):
...To evaluate the approach of gTME in a eukaryotic system, two gTME mutant libraries were created from either SPT15 (which encodes the TATA-binding protein) or one of the TATA binding protein–associated factors, in this case, TAF25 (15). The yeast screening and selection was performed in the background of the standard haploid Saccharomyces cerevisiae strain BY4741, which contains the endogenous, unmutated chromosomal copy of SPT15 and TAF25. As such, this genetic screen uses a strain that expresses both the wild-type and mutated versions of the protein and, thus, permits the identification of dominant mutations that lead to novel functions in the presence of the unaltered chromosomal gene. These libraries were transformed into yeast and were selected in the presence of elevated levels of ethanol and glucose. The spt15 mutant library showed modest growth in the presence of 5% ethanol and 100 g/liter of glucose, so the stress was increased in the subsequent
serial subculturing to 6% ethanol and 120 g/liter of glucose. After the subculturing, strains were isolated from plates, and plasmids containing mutant genes were isolated and retransformed into a fresh background, then tested for their capacity to grow in the presence of elevated glucose and ethanol levels. The best mutant obtained from each of these two libraries was assayed in further detail and sequenced. The sequence characteristics of these altered genes conferring the best properties (one Spt15p and one Taf25p) are shown in Fig. 1A.
Each of these mutated genes contained three mutations,with those of spt15 localized to the second repeat element, which consists of a set of b sheets (5, 16). These specific triple mutations in the taf25 and spt15mutant genes are thus referred to as the taf25-300 and spt15-300 mutations. The spt15-300 mutant outperformed the control at all concentrations tested, with the strain harboring the mutant protein providing up to 13-fold improvement in growth yield at some glucose concentrations (Fig. 1B and fig. S1). The taf25-300 mutant was unable to grow in the presence of 6% ethanol, consistent with the observations seen during the enrichment and selection phase. Despite these increases in tolerance, the basal growth rate of these mutants in the absence of ethanol and glucose stress was similar to that of the control. Furthermore, the differences in behavior between the spt15-300 mutant and taf25-300 mutant suggest that mutations in genes encoding different members of the eukaryotic transcription machinery are likely to elicit different (and unanticipated) phenotypic responses.
There is an interesting note in the paper that the
mutant is superior since it is able to convert 2 grams
per liter per hour. If the result were linear - and probably it's not - this suggests that a reactor filled with a liter of a glucose solution, would be able to produce 48 grams of ethanol in a period of 24 hours. This should give an idea of the economics of the process and the amount of water required for ethanol production since this
laboratory result is superior to the
existing industrial fermentation scheme. No wonder people question whether ethanol is "worth it."
As it happens talk about
research is somewhat nonsensical in connection with global climate change, since climate change is happening
now and not in some distant future. Thus, all of the options that will be useful in the approach to energy and climate change are already operating at an exajoule scale. If they are not operating an exajoule scale, they are just
talk.
In spite of this "breakthrough," and let's be clear that it has to be the greatest thing since the invention of beer, since it comes from "MIT," and not from the "South Dakota School of Mines," or from "Franklin Pierce College" or from "Orange County Community College," I predict that ethanol will still not come close to displacing a
significant amount of oil consumption in the lifetime of anyone now living. This will not stop the corn lobby from spectacularly misinterpreting the results however and demanding further obeisance to their decades of wishful thinking. I would love to be proved wrong, of course, but I won't be. If one allows the corn lobby to transcribe scientific results, one will end up with mutant impressions, and not necessarily the "best mutant," either.
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