The Food Additives p-Coumaric Acid Production from Corn Stalk Catalyzed by a Cold-Adapted Carboxylesterase

p-Coumaric acid is a widely utilized food additive with beneficial biological activities. A novel enzymatic catalysis strategy for the production of p-coumaric acid from lignocellulosic biomass is proposed herein. The gene encoding a carboxylesterase was identified in metagenome-assembled genome and further characterized in the isolated Glutamicibacter soli Em07. The target protein, with a molecular weight of 53 kDa, was successfully obtained through heterologous expression. The carboxylesterase exhibited cold adaptation, with optimal activity at 35 °C and pH 7.0 using 1-naphthyl acetate as substrate, and maintained over 75% of the maximum activity after incubation at 25 °C for 2 h. At 25 °C, 35.9 ± 0.4 μg of p-coumaric acid was obtained from 20 mg of corn stalk via carboxylesterase-mediated catalysis. This work achieves a high p-CA yield from lignocellulosic biomass via low-temperature enzymatic catalysis without pretreatment. The results offer valuable progress toward manufacturing high-value food additives, including p-CA.