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Non‐sterilized fermentative production of acetoin with 2,3‐butanediol as a main byproduct from maize hydrolysate by a newly isolated thermophilic Bacillus strain
Author(s) -
Xiao Zijun,
Gu Rulin,
Hou Xiaoyuan,
Zhao Jingyi,
Zhu Hu,
Lu Jian R
Publication year - 2017
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.5301
Subject(s) - acetoin , fermentation , food science , hydrolysate , 2,3 butanediol , chemistry , industrial fermentation , bioconversion , hydrolysis , biochemistry
BACKGROUND Acetoin is an important biorefinery platform chemical with many industrial uses. It is mainly produced by chemical synthesis or mesophilic fermentation with high costs. RESULTS A thermophilic Bacillus strain was isolated to efficiently produce acetoin from maize hydrolysate at 50°C. The fermentation medium was statistically optimized by Plackett–Burman design. Operational conditions were then optimized using a 4.2 L fermenter conducted at 50°C without sterilization. Oxygen enriched air (65% oxygen) accelerated substrate consumption but did not increase product titer. In comparison with 600 rpm, agitation speed controlled at 400 rpm yielded less acetoin but more 2,3‐butanediol in the final products. A two‐stage pH control strategy (pH first at 6.6–7.1 then at 7.7–8.0) was applied to further increase the yield of acetoin. Finally, 50.8 g L ‐1 of acetoin and 32.1 g L ‐1 of 2,3‐butanediol were obtained from 251 g L ‐1 of degermed maize flour (dry weight). The conversion yield from sugar to the 4‐carbon compounds (acetoin and 2,3‐butanediol) was 94.4% of the theoretical value. CONCLUSION This is the first report of non‐sterilized fermentative production of acetoin. Using degermed maize hydrolysate as the main feedstock, this work sets a new titer record of acetoin fermentation among known thermophilic producing systems. © 2017 Society of Chemical Industry