Background:
Currently, microbial fermentation method has become the research hotspot for acetoin production.
In our previous work, an acetoin-producing strain,
Bacillus subtilis
SF4-3, was isolated from Japanese traditional
fermented food natto. However, its conversion of glucose to acetoin was relatively low. In order to achieve a
high-efficient accumulation of acetoin in
B. subtilis SF4-3, main medium components and fermentation
conditions were evaluated in this work.
Results:
The by-products analysis showed that there existed reversible transformation between acetoin and
2,3-butanediol that was strictly responsible for acetoin production in
B. subtilis SF4-3. The carbon sources,
nitrogen sources and agitation speed were determined to play crucial role in the acetoin production. The
optimal media (glucose·H
2O 150 g/L, yeast extract 10 g/L, corn steep dry 5 g/L, urea 2 g/L, K
2HPO
4 0.5 g/L,
MgSO
4 0.5 g/L) were obtained. Furthermore, the low agitation speed of 300 r/min was found to be
beneficial to the reversible transformation of 2,3-butanediol for acetoin production in
B. subtilis SF4-3.
Eventually, 48.9 g/L of acetoin and 5.5 g/L of 2,3-butanediol were obtained in a 5-L fermenter, and the specific
production of acetoin was 39.12% (g/g), which accounted for 79.90% of the theoretical conversion.
Conclusions:
The results indicated acetoin production of
B. subtilis SF4-3 was closely related to the medium
components and dissolved oxygen concentrations. It also provided a method for acetoin production via the
reversible transformation of acetoin and 2,3-butanediol.
