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Nitrogen bacteria may save world’s crops powered by the sun

crop spraying

NITROGEN IS EVERYWHERE in the world around us and becomes inherently useful when chemically combined with other elements. In this ‘fixed state’ it can be used as a fertilizer, bulking up the crops that humans consume.

It quickly became so essential that border wars were once fought over supply. However, the environmental costs of using nitrogen fertilizer are adding up.

A fascinating article by Grist, the US environment website, describes a new scientific discovery centering on nitrogen-fixing bacteria that might allow the continued use of nitrogen as a crop fertilizer without all the harmful side-effects on the environment.

Fertilizer manufacture
uses more energy
than harnessed
by all wind and solar
in 2017

Nitrogen oxide pollution in the atmosphere is building up from its abundant use. With half of the nitrogen fertilizer used ‘running off’ into waterways, algae blooms have been forming that kill marine life and create ‘dead zones’ around the world.

The poisonous effects of nitrogen oxide also produce stifling smog in farmland, and cause oxygen deficiency in babies when found in drinking water. The gas can also seep out of the ground in the form of nitrous oxide.

More greenhouse gases than emitted by all US homes

Nitrogen fertilizer production is not friendly to our environment either. Its manufacture uses up 1% of human energy production, more energy than was harnessed by wind and solar farms last year. It also emits more greenhouse gases into the atmosphere than all American homes combined.

Grist’s article explores ways that nitrogen can still be used without harming the Earth’s environment and using masses of fossil fuels. At the forefront of scientific discovery sit nitrogen-fixing bacteria.

These bacteria have a symbiotic relationship with some plants where they get the energy to convert nitrogen from the air into ammonia and related compounds. This cuts much of the use of fossil fuels in both current nitrogen fertilizer production and its use on farms.

Scientific start-ups are starting to take advantage of a breakthrough in how to use bacteria to boost plant growth. One of these is Pivot Bio which recently received a $70 million vote of confidence following years of research into new ways to get nitrogen into plants.

It all began with two dejected scientists who had gleaned nothing in their continued research on nitrogen-fixing bacteria over a number of years. They had a breakthrough when they concentrated their efforts on soil bacteria as opposed to engineering the plant itself for nitrogen production.

Treat the plants to probiotics and fuel with solar energy

A liquid probiotic would be planted alongside crop seeds, growing the nitrogen-fixing bacteria alongside the plant. The brilliance of this is that the plant and the bacteria exchange goods. Simply put, the plant provides solar energy derived by photosynthesis which it exchanges with the bacterium for nitrogen compounds.

The Pivot scientists had picked up the trail blazed by Sharon Doty’s discovery of nitrogen-fixing bacteria occurring naturally with plants. Known as rhizobia, they kept growing over poplar tree cell cultures that Doty was attempting to study.

Previously, rhizobia bacteria were thought to occur only in plants with root nodules, such as peas and beans. Because poplar trees didn’t have root nodules, Doty logically concluded that poplars and possibly many other plants, had partnered with the nitrogen-fixing bacteria as part of a previously unknown evolutionary process.

Pivot Bio’s experiment with planting this nitrogen-fixing probiotic took hold when a small seedling, supported by this bacterium, proceeded to grow heartily in a test tube.

Other start-ups have started research in the same areas, including Azotic Technologies that have begun work with a bacterium found in sugar cane; and Intrinsyx Bio which have started testing the rhizobia bacteria that Doty discovered.

The real world hurdles

Using nitrogen-fixing bacteria as fertilizer doesn’t come without its hurdles. For instance high-yielding crops may not genetically cooperate with newly engineered nitrogen-fixing bacteria, after decades of treatment with industrial fertilizer. There is also the fear that Pivot Bio’s bacterium strain may produce so much fertilizer it could worsen the nitrogen pollution issue.

Grist spoke to Massachusetts Institute of Technology scientist Chris Voigt, who said that the more engineered an organism is, the less likely it is to spread. A bacterium that devotes energy to fixing nitrogen isn’t adapted for life in the wild – essentially like chickens who are engineered to grow breasts that are so enlarged they cannot stand.

Another hurdle is how to realistically market to farmers and logistically keep a live bacterial culture perky throughout distribution. Nitrogen-fixing bacteria would need to meet these requirements to replace industrial fertilizer as well as prove that they could cut down on the current workload of growing crops.

Pivot Bio has been working with farmers over four years, testing their nitrogen-fixing bacterium’s growth and results. They don’t expect to replace all the work currently done by industrial fertilizers but do want to cut down on the work and pollution created by current farming methods.

Consumer reaction is another hurdle. The start-ups are aware that people who are eating crops farmed with fertilizer from bacteria may not be as pleased as their farmers.

Pivot Bio has said that its bacterium doesn’t contain DNA from another species, but that the bacterial DNA has been tweaked to keep fixing nitrogen in the presence of other fertilizers. Azotic have said that their bacterium is as dangerous as eating a probiotic yoghurt.

However, the idea of new bacteria in people’s food might ruffle the feathers of anti-GMO protestors. The counter argument is that a new bacterium in our food may be a small price to pay in the shadow of a worsening nitrogen pollution and energy cost problem.

This is a condensed version of an article originally published on Grist.org

 

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