Combining Metabolic Engineering and Electrocatalysis: Application to the Production of Polyamides from Sugar

Abstract

Biorefineries aim to convert biomass into a spectrum of products ranging from biofuels to specialty chemicals. To achieve economically sustainable conversion, it is crucial to streamline the catalytic and downstream processing steps. In this work, a route that combines bio- and electrocatalysis to convert glucose into bio-based unsaturated nylon-6,6 is reported. An engineered strain of Saccharomyces cerevisiae was used as the initial biocatalyst for the conversion of glucose into muconic acid, with the highest reported muconic acid titer of 559.5 mg L(-1) in yeast. Without any separation, muconic acid was further electrocatalytically hydrogenated to 3-hexenedioic acid in 94 % yield despite the presence of biogenic impurities. Bio-based unsaturated nylon-6,6 (unsaturated polyamide-6,6) was finally obtained by polymerization of 3-hexenedioic acid with hexamethylenediamine.

Requirement of a Functional Flavin Mononucleotide Prenyltransferase for the Activity of a Bacterial Decarboxylase in a Heterologous Muconic Acid Pathway in Saccharomyces cerevisiae

“…Due to its acid tolerance and resistance to microbial contaminations, Saccharomyces cerevisiae makes an ideal host organism for production of cis,cis-muconic acid, and thus the pathway has been successfully implemented in S. cerevisiae by several groups (5)(6)(7)(8). Several approaches have been applied to improve the yield of the pathway.…”

“…Several approaches have been applied to improve the yield of the pathway. These approaches include deletion or inactivation of the E-domain of the pentafunctional yeast enzyme Aro1 responsible for the shikimate 5-dehydrogenase function of the enzyme (5,7), leading to accumulation of the precursor 3-DHS. Overexpression of a feedback-resistant mutant of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase ARO4 improved entry of precursors into the shikimic acid pathway (6).…”

“…One of the homologues (accession no. AAY57855) is organized in a BCD cluster and has been demonstrated to be highly oxygen-sensitive (5), whereas the other homologue (isomeric aroY-C [aroY-C iso ], AB479384) has been successfully utilized for cis,cis-muconic acid production in S. cerevisiae (5)(6)(7)(8) and E. coli (3,4,10,11). Contradictory results exist about the necessity to coexpress B (aroY-B; AAY57854) and D (aroY-D; AAY57856) genes to obtain decarboxylase activity in S. cerevisiae.…”

Electrochemical Conversion of Biologically Produced Muconic Acid: Key Considerations for Scale-Up and Corresponding Technoeconomic Analysis

“…One approach, which we have recently reported, entails the use of electrochemistry to mitigate the extensive separations that would be required for the conversion of biologically produced intermediates such as muconic acid (MA). 17,18 MA is a C 6 unsaturated dicarboxylic acid produced by the fermentation of cellulosic sugars and lignin-derived aromatics. In addition to recent efforts led by industry, in particular by Deinove 19 and Myriant, 20 several academic research groups have reported producing MA with high yields and titers using metabolically engineered bacteria: e.g., Escherichia coli reached 59.2 g MA L -1 at a 30% (mol MA /mol Glucose ) yield, 21 and Pseudomonas putida achieved >15 g MA L -1 using the aromatic lignin monomer p-coumarate as a feedstock.…”

“…17 These efforts have been motivated by MA's potential as a platform molecule to produce a vast array of renewable monomers of industrial importance, including adipic acid, terephthalic acid, caprolactone, 1,6-hexanediol, and 1,6-hexamethylenediamine. 18 Building blocks derived from MA are central to the manufacture of Nylon-6,6, polyethylene terephthalate (PET), and other polyesters, polyamides, and polyurethanes with an estimated global annual market greater than 22 billion U.S. dollars.…”