Table 1.

Whole‐cell biocatalysis for Neu5Ac production.

Recombinant strains	Carbon sources	Substrates	Main strategies	GlcNAc conversion rate	Product concentration	Reference
two E. coli NM522 cells and a Corynebacterium ammoniagenes strain	glucose	800 mM GlcNAc	Two E. coli NM522 expressed slr1975 from Synechocystis sp. PCC6803 and neuB from E. coli K1, respectively, coupling with Corynebacterium ammoniagenes to supply PEP.	5%	12.3 g/L	[83]
Two E. coli BL21 (DE3) cells	glucose	1200 mM GlcNAc, 1200 mM pyruvate	Two E. coli BL21 (DE3) cells expressed age from Anabaena sp. CH1 and nanA from E. coli NovaBlue, respectively.	33.3%	122.3 g/L	[84]
E. coli BL21 (DE3)	glucose	600 mM GlcNAc, 800 mM pyruvate	E. coli BL21 expressed slr1975 from Synechocystis sp. PCC6803 and nanA from E. coli K12. An AGE mutant and a more efficient NAL were identified by directed mutagenesis and molecular dynamics simulation, respectively. The transporter genes nanT and nagE were eliminated.	58.6%	108.8 g/L	[88]
S. marcescens	GlcNAc	12.5 mM GlcNAc, 10 mM PEP	S. marcescens expressed slr1975 from Synechocystis sp. PCC6803 and neuB from Campylobacter jejuni NCTC11168. Pathways fluxes were balanced through promoter swapping.	12.4%	0.48 g/L	[85]
E. coli BL21 (DE3)	glucose	800 mM GlcNAc, 1200 mM sodium pyruvate	A novel AGE BT0453 with high protein solubility cloned from Bacteroides thetaiotaomicron and E. coli NanA were expressed.	5.36%	13.27 g/L	[81]
E. coli MG1655	glycerol	45.2 mM GlcNAc	Production with different carbon sources was compared. A two-stage pH shift strategy was carried out. The GlcNAc concentration was optimized.	43.35%	18.17 g/L	[86]
E. coli BL21 (DE3)	glucose	800 mM GlcNAc, 500 mM sodium pyruvate	Gene nag and poxB were deleted from the E. coli BL21 (DE3) chromosome. Precursor feeding were conducted.	66.8%	164.88 g/L	[87]