TAGS: Sustainability / Natural Coatings
MIT chemical engineers devise a metal-organic coating that protects bacterial cells from damage without impeding their growth or function. In a new study, they found that these coated bacteria improved the germination rate of a variety of seeds, including vegetables such as corn and bok choy.
Protects Microbes from Heat & Freeze-drying
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The coating could make it much easier for farmers to deploy microbes as fertilizers,” said Ariel Furst, the Paul M. Cook Career Development assistant professor of Chemical Engineering at MIT and the senior author of the study.
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We can protect them from the drying process, which would allow us to distribute them much more easily and with less cost because they’re a dried powder instead of in liquid,” continued Furst. “
They can also withstand heat up to 132 degrees Fahrenheit, which means that you wouldn’t have to use cold storage for these microbes.”
To protect the microbes from both heat and freeze-drying, Furst decided to apply a coating called a metal-phenol network (MPN), which she has previously developed to encapsulate microbes for other uses, such as protecting therapeutic bacteria delivered to the digestive tract.
The coatings contain two components, a metal and an organic compound called a polyphenol, that can self-assemble into a protective shell. The metals used for the coatings, including iron, manganese, aluminum and zinc, are considered safe as food additives. Polyphenols, which are often found in plants, include molecules such as tannins and other antioxidants. The FDA classifies many of these polyphenols as GRAS (generally regarded as safe).
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We are using these natural food-grade compounds that are known to have benefits on their own and then they form these little suits of armor that protect the microbes,” stated Furst.
For this study, the researchers created 12 different MPNs and used them to encapsulate Pseudomonas chlororaphis, a nitrogen-fixing bacterium that also protects plants against harmful fungi and other pests. They found that all the coatings protected the bacteria from temperatures up to 50 degrees Celsius (122 degrees Fahrenheit) and also from relative humidity up to 48 percent. The coatings also kept the microbes alive during the freeze-drying process.
Cost-effective Technology to Improve Germination Rate
Using microbes coated with the most effective MPN, a combination of manganese and a polyphenol called epigallocatechin gallate (EGCG), the researchers tested their ability to help seeds germinate in a lab dish. They heated the coated microbes to 50°C before placing them in the dish and compared them to fresh uncoated microbes and freeze-dried uncoated microbes.
The researchers found that the coated microbes improved the seeds’ germination rate by 150 percent, compared to seeds treated with fresh, uncoated microbes. This result was consistent across several different types of seeds, including dill, corn, radishes and bok choy.
Furst has started a company called Seia Bio to commercialize the coated bacteria for large-scale use in regenerative agriculture. She hopes that the low cost of the manufacturing process will help make microbial fertilizers accessible to small-scale farmers who don’t have the fermenters needed to grow such microbes.
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When we think about developing technology, we need to intentionally design it to be inexpensive and accessible and that’s what this technology is. It would help democratize regenerative agriculture,” added Furst.
Source: Massachusetts Institute of Technology