**5. Conclusions**

*Rg*-PAL-harboring *E. coli* BL21(DE3) as the whole-cell biocatalyst, the productions of *trans*-cinnamic acid and *p*-coumaric acid reached to 597 mg/L and 525 mg/L, respectively, via optimizing reaction conditions. After the cells were repeatedly tested five times, the enzyme still had good catalytic activity. This engineered strain is a potential strain to produce *trans*-cinnamic acid and *p*-coumaric acid for industrial applications.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/ 10.3390/catal12101144/s1, Figure S1: The molecular docking results of PAL and L-Phe, Figure S2: Solubilities of L-Phe and L-Tyr in NaOH, Gly-NaOH and Na2CO<sup>3</sup> .NaHCO<sup>3</sup> at pH 10, Figure S3: Results of two rounds transformation of trans-cinnamic acids and p-coumaric acid, Figure S4: The standard curves for quantification of the product concentration, Figure S5: The HPLC graph of trans-cinnamic acid and p-coumaric acid.

**Author Contributions:** Y.L. (Data Curation, Investigation, Methodology, Writing—Original Draft); W.X. (Weizhuo Xu) and W.X. (Wei Xu) (Resources, Supervision, Writing—Review and Editing). All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Data are available upon reasonable request.

**Conflicts of Interest:** The authors declare no conflict of interest.
