Dual-cell co-catalytic system engineering enhances N-acetylneuraminic acid synthesis by Bacillus amyloliquefaciens

N-acetylneuraminic acid (NeuAc) is a bioactive nine-carbon sugar, and it is extensively applied in food, pharmaceutical, and cosmetic fields. However, feedback inhibition between key enzymes and metabolites adversely affects NeuAc synthesis. In this study, a novel Bacillus amyloliquefaciens dual-cell co-catalytic system was developed to relieve feedback inhibition effects, resulting in 62 % increase in NeuAc titer, and blocking consumption pathways of NeuAc precursors (N-acetylglucosamine (GlcNAc) and pyruvate) further increased NeuAc titer by 75 % (33.4 g/L). Subsequently, NeuAc-synthesizing enzyme promoter engineering increased NeuAc titer to 77.3 g/L. Finally, the maximum NeuAc titer (134.7 g/L) and GlcNAc conversion rate (77 %) were achieved under dual-cell co-catalytic optimized conditions (pH 7, cell concentration = 25 (OD₆₀₀), 0.8 mol/L GlcNAc, and xylose as carbon source). Overall, this study develops a dual-cell co-catalytic system of NeuAc efficient synthesis by Bacillus amyloliquefaciens, which exhibits great potential in the industrial production and application of NeuAc.