Acetoin production enhanced by manipulating carbon flux in a newly isolated Bacillus amyloliquefaciens

A new strain, FMME044, exhibited a remarkable ability to synthesize acetoin and was identified as Bacillus amyloliquefaciens. The following characteristics of enzyme activity were found: 2,3-butanediol was reverse transformed to acetoin upon depletion of glucose; lower agitation speeds favored 2,3-butanediol accumulation; and higher agitation speeds favored reverse transformation of 2,3-butanediol to acetoin. In order to enhance acetoin production by manipulating the carbon flux distribution, a two-stage agitation speed control strategy was proposed: during the first 24 h, the agitation speed was set to 350 rpm to achieve a high 2,3-butanediol concentration and then the speed was increased to 500 rpm to reverse transform 2,3-butanediol to acetoin. Following this strategy, a high titer (51.2 g L−1), yield (0.43 g g−1), and productivity (1.42 g L−1 h−1) of acetoin were achieved. The results demonstrated that B. amyloliquefaciens FMME044 is a potential industrial strain for acetoin production.