Production of value-added chemicals from lignocellulose is one of the key strands of the emerging bio-economy. A synthetic approach has been developed to produce p-methoxy coumarate esters from waste corn stover and corn bran, and further transform these compounds into consumer products. In the first step, p-coumaric acid (pCA) and ferulic acid (FA) are released through mild alkaline hydrolysis of corn waste, in more than 20 mgg-1 yield (10 wt% based on lignin content). Subsequently, we adopt both chemical and biological pathway to upgrade them into higher value chemicals. In the chemical pathway, heterogeneous solid acids catalyze the esterification of pCA with various alcohols. Amberlite IR-15 shows the best catalytic performance, owing to its optimal acid density, large surface area, and suitable pore diameter. The solid acid catalyst can be recycled with slight activity loss and regenerated by acid washing and vacuum drying. Finally, methylation of p-coumarate ester to give target product p-methoxy coumarate esters is carried out by using commercially available and low-cost inorganic bases (e. g., K2CO3). Base-catalyzed transesterification of methyl p-methoxy coumarate to p-methoxy coumarate esters is also investigated. In the biological pathway, we explored L-tyrosine production from pCA and used it in parallel with conventional microbial fermentation to form an integrated process for producing L-tyrosine from sugarcane bagasse biomass. From 1 g of sugarcane bagasse, an optimized alkaline hydrolysis step was performed that efficiently delignified the biomass and recovered 44 mg of pCA. The pCA obtained was converted into L-tyrosine with 49% molar conversion yield through biotransformation with whole Escherichia coli cells expressing a tyrosine ammonia lyase (TAL), yielding 24 mg of L-tyrosine. The alkaline-treated biomass residue was efficiently digested by exogenously added hydrolytic enzymes and utilized by a L-tyrosine-producing Escherichia coli strain, yielding another 25 mg of L-tyrosine. The L-tyrosine yield from the pCA biotransformation route was almost equal to that from the fermentation route, highlighting the significance of this newly described biotransformation process.

Value-added chemicals from lignin via p-coumaric acid and ferulic acid as platform

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.