Minor Phenolic Compounds in Detoxified Lignocellulosic Hydrolysates Are the Determinant Factor on Cell Growth and Metabolic Activity of <i>Escherichia coli</i>

Phenolic compounds from lignin degradation in harsh pretreatment of lignocellulose persistently exist at low concentrations in hydrolysates even after standard detoxification and enzymatic hydrolysis. This study found that minor phenolic compounds in dry acid-pretreated and biodetoxified wheat straw hydrolysates were the key inhibitors of Escherichia coli (E. coli). Multiple E. coli strains exhibited poor cell growth and metabolic activity in wheat straw hydrolysates with the presence of minor phenolics. However, the cell growth and metabolic activity of E. coli strains were significantly recovered with the declining phenolic content. Several recombinant E. coli strains successfully fermented 22.17 g/L of ethanol and synthesized 12.04 g/L of cadaverine using wheat straw hydrolysates after the removal of minor phenolics. These findings highlight the critical role of phenolic compounds in the inhibition of E. coli strains and provide a foundation for E. coli recombinants in biorefinery fermentations for biofuel and biochemical productions.