Nitrogen-fixing GM bacteria in U.S. wheat fields 2019

Pivot Bio is a Berkeley, California-based company, in the dead-center of the SynBio cradle of the world. Like multiple other biotech-companies, their focus is on food and the development of new improved crops and agriculture in a world where 45% of children are starving. But unlike the majority of their predecessors, researchers at Pivot Bio are not modifying plants or crops. Instead, they want to improve our current agricultural methods by genetically engineering bacteria.

Apart from love, water and sunshine, in order to grow, crops need fertiliser. The sun provides every plant with energy for photosynthesis, a process which combines carbon dioxide (CO2) and water (H2O) to produce carbohydrates and sugars. The fertiliser primarily provides nitrogen, the fourth most abundant element after carbon, hydrogen and oxygen. These elements are the main building-blocks of every ear of corn, every grain of wheat, and every other living organism. But though fertilisers may be vital for crops, they can be detrimental to other parts of nature, and may contaminate water and disrupt aquatic ecosystems.

 

A plant-bacteria partnership

More than 78% of our atmosphere is made up of nitrogen, but it exists in a form that is inaccessible to plants. It is however, accessible to certain types of bacteria. These bacteria can take up nitrogen from the air and transform it into ammonia, binding the nitrogen in a form that plants very much like and are able to absorb. Legumes are plants such as beans, lentils and peanuts that have capitalised on this specific type of bacteria, and grow symbiotically with them, thus not needing much additional nitrogen from external fertiliser. However, legumes are so far the only naturally occurring plant to have reached out to the nitrogen-fixing bacteria for a partnership. And that is what the field of Synthetic biology has been looking to change.

This is where Pivot Bio enters the picture. According to their website, Pivot Bio has used metagenomics to analyse multiple soil-dwelling bacteria, looking for genes involved in nitrogen-fixing and plant symbiosis. Through this wide search, they have found bacteria that contain such genes, but who have them silenced in one way or another. Silencing of genes can happen through multiple ways, when the genes in question go unused for a long time, or mutate to become unviable.

Pivot Bio claims to have identified bacteria that are able both to fix nitrogen from the air, and to live symbiotically with wheat. They then “optimised” these bacteria, and then presumably modified their genome to “reawaken” these silent genes.

Why would bacteria have these silent genes to begin with? One theory is that before modern agriculture arose, and artificial fertilisation became a thing, symbiosis between many types of plants and nitrogen fixing bacteria was more common. But as humans started to throw on heaps of fertiliser, this symbiosis became obsolete, and the genes in the bacteria, over time, became silent.

So, Pivot Bio have developed a genetically engineered bacteria that decreases the need for fertiliser, decreasing the pollution of nearby waters and aquatic eco-systems. Awesome.

This is where the real story starts. Because Pivot Bio have announced that this genetically engineered bacteria will be in wheat fields in America as soon as 2019. I personally think that Pivot Bio have created a beautiful solution to a real-world problem, using synthetic biology and biotechnology. It’s simple, it’s (as far as their research claims) effective, and it’s innovative. But this is where we encounter one of the massive hurdles of brilliantly beautiful SynBio solutions today.

 

Can we release a genetically engineered organism into the wild and be sure that there won’t be any ramifications?

This is the obstacle for bacteria engineered to clean up oil-spills and pollutants, or for engineered probiotics. Can we guarantee that it is safe to release them? Don’t get me wrong, I am not saying that there is a massive and clear threat to letting an engineered bacteria loose in the world. Quite the opposite. There is very little research to support that there would be any significant danger in releasing a bacteria into nature that is good at degrading petrol, or that produces vitamins, or fixes nitrogen. The question is not whether we can prove that it’s dangerous, because we can’t. The question is whether we can prove that it’s safe.

We can, plausibly, compare the situation to introducing an external species to a new habitat, like the foxes introduced to Australia to reduce the rabbit-population. No one expected it to be dangerous, but it turned out to wreak havoc on the ecosystem.

So, what about Pivot Bio’s engineered bacteria? Their website doesn’t explicitly say how they’ve been edited and altered, but it seems fair to assume that they have mainly up-regulated already existing and dormant genes. They state that their approach is non-transgenic, ie. they have not inserted any foreign genetic material into the bacteria. Does that set nitrogen-fixing bacteria aside completely from other engineered organisms, or does it place them somewhere in between? Wouldn’t it be rather like reintroducing an extinct creature into an ecosystem, like the megalodon or the mammoth? Couldn’t that too have a massive effect on the ecosystem they enter, regardless of them not being strictly transgenic? Honestly, I don’t know. It might even be absurd to compare bacteria with large mammals. Or it might not. We don’t know, because we haven’t tried. But come 2019, apparently, we’ll find out.

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