Cover Feature: Biotransformation of Phenolics in Spent Liquor from Aqueous Ammonia Pretreatment (ChemSusChem 22/2025)

The Cover Feature shows microbes engineered at UW-Madison’s Great Lakes Bioenergy Research Center transforming p-hydroxybenzamide (pHBAm) and p-hydroxybenzoic acid (pHBA) into 2-pryone-4,6-dicarboxylic acid (PDC). Ammonia pretreatment of poplar converts p-hydroxybenzoate esters into pHBAm, pHBA, and phenol, the structures on the leaves. While phenol is produced by decarboxylation of pHBA, it is not transformed by the microbes. More information can be found in the Research Article by S. D. Karlen and co-workers (DOI: 10.1002/cssc.202500881). Cover design by Chelsea Mamott, Shengfei Zhou and Steven D. Karlen.