cis,cis-Muconic acid, a metabolic intermediate of Klebsiella pneumonia, can be converted to adipic acid and terephthalic acid, which are important monomers of synthetic polymers. cis,cis-Muconic acid is also a biochemical material that can be used for the production of various plastics and polymers and is particularly gaining attention as an adipic acid precursor for the synthesis of nylon-6,6.