Recombinant Enzyme Expression in E. coli

E. coli BL21 and E. coli BL21 (DE3) were used. Genes for N. meningitidis CSS (UniProtKB ‐ Q7DDU0) and SiaC (UniProtKB ‐ P0A0Z8) were from Galab Laboratories. Both were cloned (Online Supporting Information) into a pC21e1 expression vector reported recently (Zhong et al., 2019 (link)). The NAL gene from L. plantarum WCFS1 (GenBank CCC80530.1) was codon‐optimized for expression in E. coli and received in a pET22b (+) vector (GenScript Biotech). The gene for ManNAc 1‐dehydrogenase (ManNAcDH, E.C. 1.1.1.233) from Flavobacterium sp. 141‐8 was kindly provided in a pET‐28a(+)‐vector by Kathrin Castiglione (Friedrich‐Alexander Universität Erlangen‐Nürnberg, Germany) (Klermund et al., 2016 (link)). E. coli strains were cultured in LB broth and agar plates.