Vitamin A making yeast. Better than sliced bread?
By Jason Major
TechNyou
Give us our daily vitamin-enhanced bread. What if scientists genetically modified a yeast to make beta carotene and used that yeast to make bread? Assuming it does what it is supposed to do, people in developing nations, especially children, could eat that bread and help prevent the diseases (eg blindness) and often death associated with deficiency of this vitamin.
This was the motivation behind a group of US students who did just this and entered their research in iGEM, the International Genetically Engineered Machine competition. They also developed modified yeast strain that makes Vitamin C (ascorbic acid). See link to John Hopkins University media release
The problem of course is whether people would accept bread made from GM yeast. Anti-GMO groups are opposed to GM wheat and rice with changed nutrient levels. The Greenpeace actions on a CSIRO wheat with changed starch characteristics is one of the more recent examples. The difference here of course is that the GM component is not a staple such as wheat. It is a yeast that only makes up a small proportion of the ingredients in bread. Would this matter? The students involved in the project think the fact that yeast is such a small component of the bread ingredients it should be accepted, though they have yet to do the planned public attitude surveys to find out. From the construction of their survey questions it appears they want to survey those in developing nations who would be the likely recipients of their bread. The results of this would be interesting to know as so far we have a reasonable understanding of the public attitudes of people in developed nations such as Australia and to some extent the political stance of some developing nations but only anecdotal evidence (that I have come across) of what those in developing nations think of this, especially those that are suffering the micronutrient deficiencies these foods are trying to correct.
The student’s survey, lab notes and all loads of other info about their project is on their project website
Having their bread and trying hard not to eat it too
This is research that has moved beyond simply modifying the yeast – they have called it VitaYeast. They have used it to make bread. The bread has beta carotene in it. It looks and smells like bread. The students unfortunately can’t see if it tastes like bread. Because of its GMO status it can’t be eaten until it has undergone safety testing and regulatory approval. Bit like learning how to make chocolate and being told you can’t lick the spoon.
Variability in the system
I can’t determine from their results if the amount of beta carotene or Vitamin C in the bread is sufficient to have any clinical effect – not my area of expertise – but this is early days in their research and they have proof of principle, at least. Part of their future research will involve screening yeast cells that produce varying levels of beta carotene and Vitamin C to find those that are making amounts of these vitamins that will be functional in their role of helping prevent micronutrient deficiency. That is, whenever you generate a genetically modified organism you get a huge amount of variability in the individuals that have been modified, whether it be a yeast or bacteria cell, or a more complex organism such as a plant or animal. This is because the gene insertion process is a random one. Scientists have little control over where the gene construct will insert itself in the host genome. The position of the insertion can influence the activity of the transgene or influence the activity of the existing genes of the host organism – often detrimentally. So apart from eliminating the individuals that have undesirable characteristics because of where the gene inserted, you have to screen for the individuals that have a gene inserted in a desirable location where it is stable over many generations (ie it doesn’t jump around to different spots in the genome), that the gene is doing the job you intended and not disrupting the function of the host genes in any undesirable way.
Even if they succeed at this scientific level there is no guarantee of success. It has to then run the gauntlet of public attitudes and expensive regulatory hoops and hurdles, which will at best take years.
iGEM
iGEM is do-it-yourself genetic engineering, or synthetic biology. Sometimes I find it hard to distinguish between genetic engineering and synthetic biology, except that maybe synbio is a more ambitious, brazen form of gen engineering. More distinctly, I guess syn bio might be described as taking the concept of DNA as simply a bunch spare parts that can be used to build or completely rejig the function of an organism, which at this stage is limited to single-celled ones such as bacteria and yeast.
iGEM is a competition that gets students to explore the possibilities of these ambitious and brazen ideas, often successfully and it is based on the use of biobricks, which are those DNA spare parts.
Biobricks
Biobricks are standardised biological parts based on DNA that can be incorporated into living systems to construct new living systems. The biobrick parts are kept in a registry and there is a Biobricks Foundation that oversees all this.
Here is what the Biobricks Foundation has to say about themselves
“We are dedicated to advancing synthetic biology to benefit all people and the planet. To achieve this, we must make engineering biology easier, safer, equitable, and more open. We do this in the following ways: by ensuring that the fundamental building blocks of synthetic biology are freely available for open innovation; by creating community, common values and shared standards; and by promoting biotechnology for all constructive interests.”
I have said it before and I’ll say it again, “tis a brave new world.”
Image: Photo by Will Kirk/Homewoodphoto.jhu.edu .