Artificial consortium that produces riboflavin regulates distribution of acetoin and 2,3‐butanediol by Paenibacillus polymyxa CJX518

The introduction of an NADH/NAD + regeneration system can regulate the distribution between acetoin and 2,3‐butanediol. NADH regeneration can also enhance butanol production in coculture fermentation. In this work, a novel artificial consortium of Paenibacillus polymyxa CJX518 and recombinant Escherichia coli LS02T that produces riboflavin (VB 2 ) was used to regulate the NADH/NAD + ratio and, consequently, the distribution of acetoin and 2,3‐butanediol by P. polymyxa . Compared with a pure culture of P. polymyxa , the level of acetoin was increased 76.7% in the P. polymyxa and recombinant E. coli coculture. Meanwhile, the maximum production and yield of acetoin in an artificial consortium with fed‐batch fermentation were 57.2 g/L and 0.4 g/g glucose, respectively. Additionally, the VB 2 production of recombinant E. coli could maintain a relatively low NADH/NAD + ratio by changing NADH dehydrogenase activity. It was also found that 2,3‐butanediol dehydrogenase activity was enhanced and improved acetoin production by the addition of exogenous VB 2 or by being in the artificial consortium that produces VB 2 . These results illustrate that the coculture of P. polymyxa and recombinant E. coli has enormous potential to improve acetoin production. It was also a novel strategy to regulate the NADH/NAD + ratio to improve the acetoin production of P. polymyxa .