Scientists at the University of Illinois have engineered a genetically modified yeast to enhance fermentation and eliminate byproducts that cause hangovers. The question is, how will altering natural yeast in fermentation processes affect the chemical constituents in wine once metabolized?
Food scientists have been looking to incorporate additives consisting of a series of chelation compounds to wine to prevent it from looking, smelling and tasting funky after oxidation. The problem is, many of them are toxic to living cells. A new method of modifying yeast may bypass additives altogether.
“Fermented foods–such as beer, wine, and bread–are made with polyploid strains of yeast, which means they contain multiple copies of genes in the genome. Until now, it’s been very difficult to do genetic engineering in polyploid strains because if you altered a gene in one copy of the genome, an unaltered copy would correct the one that had been changed,” said Yong-Su Jin, a U of I associate professor of microbial genomics and principal investigator in the Energy Biosciences Institute.
Recently scientists have developed a “genome knife” that cuts across multiple copies of a target gene in the genome. Jin’s group has now used this enzyme, RNA-guided Cas9 nuclease, to do precise metabolic engineering of polyploid Saccharomyces cerevisiae strains that have been widely used in the wine, beer, and fermentation industries.
Before this process was developed, genetically engineering yeast proved difficult due to its lack of auxotrophic markers — gene mutations that make it impossible to synthesize certain compounds that are necessary for growth, forcing the organism to search for its lacking compounds in its environment. However, the development of the “knife” allows scientists to generate synthetic auxotrophic markers, which can then be manipulated to change the genetic make-up of the yeast.
There are many problems with promoting a genetically modified wine that promises to cure hangovers. First, hangovers are caused by many different factors, so removing the hangover-causing toxins in wine won’t be anywhere near effective at ensuring the elimination of hangovers.Some scientists have pointed to acetaldehyde, a demonstrably toxic byproduct of ethanol breakdown in the body. It’s a nice theory–but it turns out that hangover symptoms are at their worst when acetaldehyde levels are low.
Secondly, what really causes hangovers is an inflammatory response, like what happens when we get an infection. No amount of genetic modification of the fermentation process will change that because ethannol itself causes elevated levels of molecules called cytokines, which are used as communication signals by the immune system. Potentially even more interesting, higher-than-normal cytokine levels also interfere with memory formation–which might account for ethanol-Ârelated lapses in recall as well.
Lastly, Gamma aminobutyric acid, or GABA is an inhibitory neurotransmitter and only something that blocks the effects of ethanol on GABA receptors could theoretically prevent a hangover. That’s not something a genetically modified wine could achieve unless the ethanol content was entirely removed.
Interfering With Specific Microorganisms Could Have Unintended Consequences
Genetic enginerring is based on the naive understanding of the genome based on the One Gene – one protein hypothesis of 70 years ago.
By precisely engineering the genome of the yeast, the scientists must “trim” the yeast as per specifications, explained Yong-Su Jin.
Scientists are creating designed mutations to determine the function of specific genes and via manipulating of yeast they are also tinkering with genetics that may produce less than desirable results. They are still deleting genes until a distinctive flavor is achieved and genes have been isolated for specific characteristics.
Foreign genes disrupt the DNA at the insertion sites and create genome-wide changes in gene expression. The changes, which are in addition to the deletions and mutations, are not predictable and have may cause specific alterations and massive changes with multiple health-related effects. The interruption of specific gene sequences in yeast may on other foreign genes which may overproduce an allergen, toxin, carcinogen or antinutrient, or regulators that block other genes.
Small RNA sequences in enzymes can also regulate gene expression, most commonly by silencing genes. The RNA is stable, survives digestion and can impact gene expression in mammals that ingest it. Genetic modification introduces new DNA combinations and mutations, which increase the likelihood that harmful regulatory RNA will be accidentally produced.
A few wineries’ decision to use GMO yeast could affect the entire North American market. Since these wines are unlabeled, the only way people can avoid them is to avoid all wines from North America, except those labeled organic, and few wines are labeled organic, due to the addition of sulfites during the winemaking process. Consumers in Europe and Asia are very informed regarding GMOs and have resoundingly rejected them. American consumers are becoming more aware, and polls show that a majority of Americans would prefer to avoid them.
Far too little is known on the long-term health effects of genetically engineered wine and for this reason should be left on the shelf if it ever makes it to mass markets.