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 24h, the agitation speed was set to 350rpm to achieve a high 2,3-butanediol concentration and then the speed was increased to 500rpm to reverse transform 2,3-butanediol to acetoin. Following this strategy, a high titer (51.2gL(-1)), yield (0.43gg(-1)), and productivity (1.42gL(-1)h(-1)) of acetoin were achieved. The results demonstrated that B. amyloliquefaciens FMME044 is a potential industrial strain for acetoin production.