(409f) Green Production of L-Alanyl-L-Glutamine By an Efficient Yeast Biocatalyst Expressing ?-Amino Acid Ester Acyltransferase without N-Glycosylation

L-Alanyl-L-glutamine (Ala-Gln) is a widely used high value-added dipeptide. An efficient and high-quality biocatalyst plays an essential role in the green production of Ala-Gln. Current yeast biocatalysts expressing α-amino acid ester acyltransferase (SsAet) possessed relatively low activity, which may be attributed to glycosylation of SsAet. In order to promote SsAet activity in yeast, N-linked glycosylation site was first identified as the Asn residue at position 442. Subsequently, we successfully eliminated the negative effect of N-glycosylation on SsAet by the removal of both artificial (α-factor) and the native signal peptide, thereby obtaining a novel yeast biocatalyst K3A1 with significantly improved activity. Besides, the optimal reaction conditions (25^oC, pH 8.5, AlaOMe/Gln=1/2) of strain K3A1 were determined to achieve the maximum molar yield and productivity of approximately 80% and 1.74 g·(L·min)^-1 against the substrate AlaOMe, respectively. Consequently, we established a yeast whole-cell biocatalyst K3A1 to achieve the green production of Ala-Gln in a safe, efficient, and sustainable manner. Our system with a sustainable process provides a prospective approach for commercial Ala-Gln production with property of reusability and product safety in the future.