MIT engineers have found that coating seeds with silk, treated with bacteria that can naturally produce nitrogen fertilizer, to facilitate the development of germinating plants. Their study was able to show that these silk-coated seats can grow normally even in unproductive soils. The team hopes that this process might make the currently ‘unsuitable’ lands suitable for agriculture, as the method is cost-effective and does not need any specialized equipment. The team’s work has been outlined in the journal PNAS.
The work spun out of previous work by Professor Benedetto Marelli, Department Civil and Environmental Engineering, which focused on the use of silk to extend the shelf life of seeds that are considered to be food crops. These fertilizers utilize microbes that can symbiotically exist with certain plants and capture nitrogen from the air to convert it into a form that is easily accepted by the plants. Even though these nitrogen-converting bacteria are naturally found in soils across the globe, with different local varieties seen in different regions, they are tough to preserve outside their natural soil environment. Silk can help preserve the biological material, which is why the researchers tested it on the nitrogen-fixing bacteria ‘rhizobacteria.’ After the preliminary tests did not give the desired results, the team decided to add a kind of sugar known as ‘trehalose’ to the mix, which helps some organisms survive low-water conditions. They suspended the bacteria, silk, and trehalose in water and soaked the seeds in the solution for a few seconds to get even coating.
They then tested the seeds at both MIT and a research facility at the Mohammed VI Polytechnic University in Ben Guerir, Morocco. The resulting plants, assisted by ongoing fertilizer production by the bacteria, showed better development compared to untreated seeds and grew successfully in soil fields ‘unproductive’ for agriculture, explains Professor Marelli. These coatings might be applied to seeds either by dipping or spray coating, both of which can be carried out in ambient pressures and temperatures.