Living lego

January 2013
Bread Slices
GM yeast in your your daily bread?
Photo by SliceOfChic on Flickr
Just as GM plants were about to hit our food chain in the 1990s, a study was published which illustrated one of the key dangers of genetic transformation.

The paper described GM yeast cells which were created with artificial genes created to boost their production of alcohol. However, besides the desired end-product, the metabolic distortion from the inserted DNA pushed the alcohol pathway into alternative routes. The result was the accumulation of a toxin in the cells normally only present at negligible concentrations: the harmful by-product even reached levels sufficient to induce mutations.

In this early attempt at GM, the toxin stopped cell growth and so was self-limiting. It demonstrates, however, a clear potential for quantities of a novel substance to be released into the yeast's surroundings (the bit we eat and drink), or for the creation of a novel pathogenic yeast strain. Yeast in the environment is uncontrollable.

The authors sensibly commented in this early paper:
“These results illustrate that careful thought should be given to the potential metabolic products and their safety when a genetically engineered yeast is applied to food-related fermentation processes.”
Twenty years on, universities are churning out science graduates who often know little beyond DNA analysis, creation and manipulation. Potential side-effects and safety considerations are not high on the curriculum.

Life is no longer a coherent, sentient, reactive, self-determining entity. Undergraduates are taught that life is a collection of standard, interchangeable, biological components. These can be synthesised and slotted together to design and build biological systems which operate within living cells, also called 'synthetic biology' or 'synbio'. And, they make a lot of money

In the UK, the Department for Business, Innovation and Skills (BIS) has set aside £20 million to help make the UK a world leader in research and application of synthetic biology.

And, just in case the bright young minds become diverted by the harmony, diversity, and inherent problem-solving adaptations of nature, students are now being educated through competitions. The International Genetically Engineered Machine (iGEM) Foundation invites student teams to design and build novel biological systems with money-making potential. Projects may also involve such ethical issues as how to prevent public fear of synthetic biology.

Most iGEM projects involve commercially-useful GM bacteria, which are particularly easy to create. It's notable however that, in their book, there seems little distinction between bacteria and yeast cells. Yeasts are micro-fungi: they're much more complex organisms than bacteria, and liable to much more complex metabolic disruption when their genome is disturbed.

One US team involved in the iGEM competition has produced a GM yeast which generates vitamin A, and can be used to make vitamin-enriched bread. The students' view is that bread made with their 'VitaYeast' has to be safe because “VitaYeast is a tiny component - it gets killed in the bread. We're not genetically modifying the wheat. We're not genetically modifying the flour or the water. We're genetically modifying something like 1 percent of the bread recipe. When you bake VitaYeast bread and you look at it, it looks like normal bread”.

This lack of any awareness of the disease-causing potential of trace amounts of a toxin is worrying. Even more so since 'vitamin A' isn't a single substance with straightforward nutritional benefits. There are no details about what vitamin-A related substance (or substances) the GM yeast actually produces, nor how much of each diffuses through the bread while it is rising but there's no reason to expect it (or them) to be safe.

The problems with artificial vitamin A
(Vitamin A supplements are usually in the form of β-carotene, which is a vitamin A precursor)
  1. Research has revealed that beta-carotene in the diet is broken down in plants and animals to form a host of biologically active derivatives which can circulate in the body: only one of these is vitamin-A, some of them promote the activity of the vitamin form, others inhibit it and could cause deficiency diseases.
  2. The 'CARET' study found that β-carotene supplements were linked to cancer
  3. Vitamin A is the biochemical precursor of retinoic acid. Retinoic acid is essential to normal embryo development. Unnatural forms of β-carotene or vitamin A carry a risk of disturbing retinoic acid metabolism with fatal or teratogenic consequences.
  4. Who knows what other risks might be associated with GM versions of vitamin A, especially when they are generated in a fast fermenting dough and possibly in combination with other novel substances.

There's no reason to assume the absence of toxins in any GM yeast. Nor is there any reason to assume the vitamin A produced by the GM yeast is safe in bread. Nor is there any reason to assume the GM yeast is safe for bakers to handle. Nor is there any reason to assume that GM yeast spreading through the environment is safe for all those who come in contact with it. In other words, small size, low concentrations and heating do not guarantee toxins will disappear or be below harmful levels.

EcoNexus scientists have warned:
There is currently no mechanism to halt a technology the public does not want and views as dangerous. The problem is compounded by the fact that equipment is increasingly cheap and almost anyone can access and use DNA sequences, unsupervised, for any purpose, with potential for deadly mistakes and aggressive applications ... We must beware of becoming like the proverbial frog in the slowly heating water - it does not perceive the gradual change in temperature, fails to jump out while it still can, and is finally boiled.”

People will indeed end up like the slowly boiled frog in a weird world full of synbio monsters they never saw coming. Unless, that is, YOU tell them to start complaining about the living lego life-forms, created for profit with no safety testing, nor even any recognition of the need.

  • Tomoko Inose and Kousaku Murata, 1995, Enhanced accumulation of toxic compound in yeast cells having high glycolytic activity: a case study on the safety of genetically engineered yeast,International Journal of Food Science and Technology 3
  • Michael Antoniou comment, Synbio for vit A enriched bread, GM Watch 26.10.11
  • Sliced Bread Just Got Better, Johns Hopkins University,, 25.10.11
  • The International Genetically Engineered Machine Foundation (iGEM),, December 2012
  • Glasgow University Newsletter, December 2012
  • Helena Paul and Ricarda Steinbrecher, Slowly boiling the frog? Reasons for disquiet over synthetic biology, Scientists for Global Responsibility Newsletter, Issue 41, Autumn 2012

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