Enhanced 2,3-Butanediol Production by Optimizing Fermentation Conditions and Engineering <italic>Klebsiella oxytoca</italic> M1 through Overexpression of Acetoin Reductase

Title
Enhanced 2,3-Butanediol Production by Optimizing Fermentation Conditions and Engineering <italic>Klebsiella oxytoca</italic> M1 through Overexpression of Acetoin Reductase
Authors
조숙형김태연우한민이진원김연제엄영순
Keywords
2,3-butanediol; Klebsiella oxytoca; acetoin
Issue Date
2015-09
Publisher
PLoS ONE
Citation
VOL 10, NO 9, 1-16
Abstract
Microbial production of 2,3-butanediol (2,3-BDO) has been attracting increasing interest because of its high value and various industrial applications. In this study, high production of 2,3-BDO using a previously isolated bacterium Klebsiella oxytoca M1 was carried out by optimizing fermentation conditions and overexpressing acetoin reductase (AR). Supplying complex nitrogen sources and using NaOH as a neutralizing agent were found to enhance specific production and yield of 2,3-BDO. In fed-batch fermentations, 2,3-BDO production increased with the agitation speed (109.6 g/L at 300 rpm vs. 118.5 g/L at 400 rpm) along with significantly reduced formation of by-product, but the yield at 400 rpm was lower than that at 300 rpm (0.40 g/g vs. 0.34 g/g) due to acetoin accumulation at 400 rpm. Because AR catalyzing both acetoin reduction and 2,3-BDO oxidation in K. oxytoca M1 revealed more than 8-fold higher reduction activity than oxidation activity, the engineered K. oxytoca M1 overexpressing the budC encoding AR was used in fed-batch fermentation. Finally, acetoin accumulation was significantly reduced by 43% and enhancement of 2,3-BDO concentration (142.5 g/L), yield (0.42 g/g) and productivity (1.47 g/L/h) was achieved compared to performance with the parent strain. This is by far the highest titer of 2,3-BDO achieved by K. oxytoca strains. This notable result could be obtained by finding favorable fermentation conditions for 2,3-BDO production as well as by utilizing the distinct characteristic of AR in K. oxytoca M1 revealing the nature of reductase.
URI
http://pubs.kist.re.kr/handle/201004/50309
ISSN
19326203
Appears in Collections:
KIST Publication > Article
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