GM-free Scotland

News | August '07 | GM wine

Did you know that wine produced using GM yeast has been marketed in the US for the past three years?

Wine making involves processing grape juice with micro-organisms. Yeast feeds on the juice to produce alcohol and urea as its metabolic waste products. The alcohol, of course, is what wine-drinkers want. The urea, unfortunately, can react with the alcohol leading to the production of urethane, a suspected carcinogen. Also necessary, for the desired taste of wine, is the action of bacteria which convert unwanted acidity into lactic acid.

The US Food and Drug Agency (FDA) has approved two GM yeasts for use in wine-making. One has had genes inserted for lactic acid production, thus combining the alcohol generation and acidity regulation in a single micro-organism. The second GM yeast has inserted an activated version of one of its own, normally inactive, genes which removes urea.

The genetic transformation of yeast is much more controlled than that of crop plants. The artificial DNA is constructed and multiplied inside bacteria in the same way, but by adding in a section of yeast-lookalike-DNA the novel gene can be inserted into a chosen existing gene whose function is then knocked out.

The advantage of this precision is that there are fewer unexpected disruptions to the structure and function of the genome. The downside is that the relative precision of the transformation gives regulators an excuse to take their eyes off the ball. Worse still, GM organisms modified with genes copied from the same species have been labelled 'self-cloning'. Self-cloned GMOs have been declared, for example by the Japanese regulators responsible for assessing sake yeast, as “not covered by regulations over GM organisms”.

The potential problems of GM yeast are huge.

All genes are connected in a complex functional network (OUR COMMENT commonly known as 'life') and unexpected accumulations of toxic metabolites have already been recorded in 'self-cloned' yeasts. Add to this that yeast cells multiply at a very fast rate in wine and are notoriously unstable, with sudden chromosome rearrangements being commonplace. Where transgenes are involved in such changes, there can be unexpected toxicity in the final product.

Besides the complexity of the living yeast cells in which genomic disturbances from genetic transformation might yield toxic by-products, the complexity of the wine in which it has been growing will come into play. In one study, mice given the unwanted by-product, urethane, developed more cancers than those given wine spiked with urethane. In other words the ultimate qualities of the wine are far from that of a simple mixture of chemicals which can be listed as harmful or harmless. The unpredictable effects on the final product of the GM yeast designed to prevent urethane production adds yet a further layer of complexity.

The second major concern is the persistence of yeast in wine. DNA released from yeast cells can interact with microbes of the gut and is present in young wines for up to six months. Culturable (i.e. live) yeast cells can be recovered from unfiltered wines after several years and even in filtered, bottled wine were present in two out of five tested. Yeast is, of course, uncontainable and can be found in the proximity of wineries, mainly in water run off. Studies of abandoned wineries show that wine-yeast strains persist for over 90 years, and it has been possible to identify the species of yeast used by the ancient Egyptians in 3150 BC from wine jars in tombs. It is clear that all GM yeasts will end up in the environment where they will interbreed with wild yeasts, bakers yeast, brewers yeast etc. The hybrids formed will be capable of some very unusual fermentations inside you and your food and your soil.

GM yeast for beer making was one of the first GMOs approved for use in the UK during the 1990s, but is rumoured never to have been used. In the US, the FDA alone reviews and approves GM yeasts without consideration of environmental and human health consequences. The Institute of Science in Society notes that FDA information does not appear to be readily accessible and that their 'Generally Recognised as Safe' (GRAS) notice on GM wine yeast reads more like a public relations release on behalf of its promoters. The Agency is happy to believe the word of wine distributors that their wine is free of GM yeast, but no data have been presented and observations to the contrary have been described above.

And, the problem is about to get much bigger.

The production of alcohol during fermentation is self-limiting because of the yeasts' inability to grow at high alcohol levels. In the quest for more efficient production of biofuels, a great deal of effort is being devoted to creating yeast strains which can tolerate high ethanol levels. These won't be tested for toxic effects, because they are not for food-use, and won't be any more easily contained than GM wine-yeasts.

OUR COMMENT

Yeast cells are ubiquitous in our environment, our soil and our bodies. Anyone who has battled the miseries of a persistent thrush infection can't fail to appreciate the dangers of filling our world and food with peculiar, unstable yeasts.

You have three options open to you:

  1. Drink yourself into a cirrhotic stupor: then GM wine or thrush will be the least of your worries.
  2. Go teetotal, give up bread and cross your fingers.
  3. Stop supporting the wine-makers and brewers unless they can give you an absolute assurance that they do not use GM yeast.

SOURCES

About Us | Contact Us |2007 GM-free Scotland