In a novel biotechnological process recently detailed in the Journal of the American Chemical Society, Berl Oakley, Irving S. Johnson Distinguished professor of molecular biology at the University of Kansas (KU, Lawrence, U.S.) and collaborators at the University of Southern California (USC, Los Angeles, U.S.) have developed a chemical procedure for breaking down and removing the matrix from carbon fiber-reinforced polymers (CFRP) such that recovered carbon fiber plies exhibit mechanical properties comparable to those of virgin manufacturing substrates.

One of the major matrix breakdown products is benzoic acid, and to recover additional value, Oakley has developed a genetically modified version of the fungus Aspergillus nidulans that can feast on benzoic acid to produce a valuable chemical compound called OTA (2Z,4Z,6E)-octa-2,4,6-trienoic acid). According to Oakley and his collaborators on the new paper, “This represents the first system to reclaim a high value from both the fiber fabric and polymer matrix of a CFRP.”

Oakley is a longtime collaborator with the paper’s lead author, Clay Wang of USC. “We've been working for years with his lab to produce secondary metabolites in Aspergillus nidulans,” Oakley says. “Secondary metabolites are compounds the fungus produces — penicillin is the archetypal secondary metabolite —that have biological activity, like inhibiting its competitors and so on. The Asperlin pathway is something that came out of that work. Asperlin is a secondary metabolite. We managed to turn on a particular pathway, and that was the product. We discovered that OTA is an intermediate in the pathway and OTA is a potentially valuable industrial compound.”

“OTA can be used to make products with potential medical applications, like antibiotics or anti-inflammatory drugs,” Wang explains in a statement issued by USC. “This discovery is important because it shows a new, more efficient way to turn what was previously considered waste material into something valuable that could be used in medicine.”

Next, Oakley says his KU lab will try to make their specialized fungus even more efficient, keeping in mind needs for scalability and profitability if the new carbon-fiber recycling method is to be applied at the industrial scale. 

“Since this work began, we’ve developed strains that are actually better than the original ones,” he said. “These newer strains will likely give better results, but we’ll need to do lots of work to engineer this process into the improved strains.”

At KU, Oakley was joined in the research by graduate student Cory Jenkinson. At USC, Wang’s co-authors were Clarissa Olivar, Zehan Yu, Ben Miller, Maria Tangalos, Steven Nutt and Travis Williams.