Ongoing fungi research at the University of Kansas is helping transform hard-to-recycle plastic waste from the Pacific Ocean into a key component of pharmaceutical manufacturing.
A chemical-biological approach to transforming polyethylene uses an everyday soil fungus called genetically modified Aspergillus nidulans. This result was recently reported in the paper “Conversion of Polyethylenes into Fungal Secondary Metabolites” published in Angewandte Chemie, the journal of the German Chemical Society.
“What we did in this paper is first use oxygen and some metal catalyst (not particularly harmful or expensive) to decompose polyethylene. ,” said co-author Berl Oakley (Irving S. Johnson). Distinguished Professor of Molecular Biology, Kyushu University.
A long chain of carbon atoms from decomposed plastic was then fed to a genetically engineered Aspergillus bacterium. As designed, the fungi metabolized them into a range of pharmacologically active compounds, including commercially viable yields of asperbenzaldehyde, citreoviridine, and mutilin.
Unlike previous approaches, the fungi quickly digested plastic products like “fast food,” Oakley said.
The two things that make this approach different are that it’s chemical and it’s fungi,” he said. “But it’s also relatively fast. Repeating these attempts over and over again allows the fungus to digest the material, whereas plastic is so hard to break down that it takes months. But this breaks down the plastic very quickly, and you can have the final product in less than a week.”
The KU researchers added that the new approach is “weirdly” efficient.
“Of the bulk of the diacid that goes into the culture, 42% comes back as the final compound,” he said. “If our technology were a car, it would run 200 miles per hour, 60 miles per gallon and on recycled cooking oil.”
Previously, Oakley collaborated with corresponding author Clay Wang of the University of Southern California to produce about 100 fungal secondary metabolites for a variety of purposes.
“Fungi have been found to make many compounds that are useful to fungi in that they inhibit the growth of other organisms – penicillin is a canonical example,” Oakley said. The compounds are not necessary for the growth of organisms, but they help protect against and compete with other organisms.”
For a while, scientists thought they had capitalized on the potential of fungi to produce these compounds. But Oakley said the era of genome sequencing has unlocked new possibilities for harnessing secondary metabolites to benefit humanity and the environment.
“We realized there were so many clusters of genes that make secondary metabolites that no one had discovered, and there are millions of species of fungi,” Oakley said. “Many companies have done a good job over the years, but it was very imperfect because they were growing things in incubators and looking at producing new compounds. But 95% of gene clusters is not turned “on” until it is needed. they weren’t doing anything. So there is much more to discover. “
Oakley’s lab at KU has refined gene-targeting procedures to alter the expression of genes in Aspergillus nidulans and other fungi to generate new compounds.
“We are now sequencing the genomes of many fungi, and we can recognize the signatures of groups of genes that make chemical compounds,” he said. We can delete them from the genome and we can do all sorts of things to them We can see that there are a lot of these secondary metabolite gene clusters out there and our gene targeting procedure allowed us to turn on some of those clusters, at least in principle.”
Oakley and Wang’s co-authors were Chris Rabot, Yuhao Chen, Swati Bijlani, Yi-Ming Chiang, and Travis Williams from USC, and Elizabeth Oakley from KU.
Researchers focused on developing secondary metabolites to digest polyethylene plastic. Because these plastics are very difficult to recycle. The project harvested polyethylene from the Pacific Ocean collected at Catalina Harbor on Santa Catalina Island, California.
“There have been many attempts to recycle plastic, some of which have been recycled,” Oakley said. “A lot of it is basically melted and spun into fabric and made into a variety of other plastic products.
KU investigators said the long-term goal of the study is to develop a procedure that will break down all plastics into food-useable products by fungi, eliminating the need to sort them during recycling. . He added that the research epitomizes his KU Earth, Energy + Environment research theme and aims to “develop a better understanding of how the Earth and its inhabitants sustain life.”
“I think we all know that plastic is a problem,” Oakley said. “They accumulate in our environment. There is a large area in the North Pacific where they tend to accumulate. The squirrels around my house have even learned to line their nests with plastic bags. If we can make something useful for the price, it becomes economically viable.”
Original: Using fungi, researchers transform ocean plastic into raw material for pharmaceutical industry
Than: University of Kansas | University of Southern California
