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Conversion of Enantiomers during the Separation of Acetoin from Fermentation Broth. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8070312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Acetoin (AC) is an important platform compound with two enantiomers (R)-AC and (S)-AC. Due to its unique spatial structure, optically pure AC has particularly high application in asymmetric synthesis. Highly optically pure AC could be produced from glucose using biofermentation technology. In this paper, we have observed that the recovered AC product from the fermentation broth containing (R)-AC was a racemic mixture. The changes of the enantiomeric excess (e.e.) of (R)-AC enantiomers in the feed solution during the recovery process were then investigated, confirming that the racemization occurs during solvent distillation. Further studies showed that high temperature is the main factor affecting the conversion of the two enantiomers, while low temperature significantly prevents this conversion reaction. Therefore, we optimized the solvent recovery process and used vacuum distillation to reduce the distillation process temperature, which effectively prevented the racemization: obtains AC products with more than 98% purity and successfully maintained the proportion of (R)-AC above 96%. To our knowledge, this is the first report on the factors affecting the enantiomeric purity in the downstream extraction process of AC production by fermentation.
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Abstract
The growing need for industrial production of bio-based acetoin and 2,3-butanediol (2,3-BD) is due to both environmental concerns, and their widespread use in the food, pharmaceutical, and chemical industries. Acetoin is a common spice added to many foods, but also a valuable reagent in many chemical syntheses. Similarly, 2,3-BD is an indispensable chemical on the platform in the production of synthetic rubber, printing inks, perfumes, antifreeze, and fuel additives. This state-of-the-art review focuses on representatives of the genus Bacillus as prospective producers of acetoin and 2,3-BD. They have the following important advantages: non-pathogenic nature, unpretentiousness to growing conditions, and the ability to utilize a huge number of substrates (glucose, sucrose, starch, cellulose, and inulin hydrolysates), sugars from the composition of lignocellulose (cellobiose, mannose, galactose, xylose, and arabinose), as well as waste glycerol. In addition, these strains can be improved by genetic engineering, and are amenable to process optimization. Bacillus spp. are among the best acetoin producers. They also synthesize 2,3-BD in titer and yield comparable to those of the pathogenic producers. However, Bacillus spp. show relatively lower productivity, which can be increased in the course of challenging future research.
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Aggregation properties of amphiphilic poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) block copolymer studied by cyclic voltammetry. J SURFACTANTS DETERG 2015. [DOI: 10.1007/s11743-004-0322-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Electrochemical behaviour of gamma hydroxybutyric acid at a platinum electrode in acidic medium. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.07.231] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Zhang X, Zhang R, Bao T, Yang T, Xu M, Li H, Xu Z, Rao Z. Moderate expression of the transcriptional regulator ALsR enhances acetoin production by Bacillus subtilis. ACTA ACUST UNITED AC 2013; 40:1067-76. [DOI: 10.1007/s10295-013-1303-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Accepted: 06/03/2013] [Indexed: 10/26/2022]
Abstract
Abstract
Acetoin, a major extracellular catabolic product of Bacillus subtilis cultured on glucose, is widely used to add flavor to food and also serves as a precursor for chemical synthesis. The biosynthesis of acetoin from pyruvate requires the enzymes α-acetolactate synthase (ALS) and α-acetolactate decarboxylase (ALDC), both of which are encoded by the alsSD operon. The transcriptional regulator ALsR is essential for the expression of alsSD. Here we focused on enhancing the production of acetoin by B. subtilis using different promoters to express ALsR. The expression of reporter genes was much higher under the control of the HpaII promoter than under control of the PbdhA promoter. Although the HpaII promoter highly enhanced transcription of the alsSD operon through overexpression of ALsR, the production of acetoin was not significantly increased. In contrast, moderate enhancement of ALsR expression using the PbdhA promoter significantly improved acetoin production. Compared with the wild-type, the enzyme activities of ALS and ALDC in B. subtilis harboring PbdhA were increased by approximately twofold, and the molar yield of acetoin from glucose was improved by 62.9 % in shake flask fermentation. In a 5-L fermentor, the engineered B. subtilis ultimately yielded 41.5 g/L of acetoin. Based on these results, we conclude that enhanced expression of ALDC and ALS by moderately elevated expression of the transcriptional regulator ALsR could increase acetoin production in recombinant B. subtilis.
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Affiliation(s)
- Xian Zhang
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi Jiangsu People’s Republic of China
| | - Rongzhen Zhang
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi Jiangsu People’s Republic of China
| | - Teng Bao
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi Jiangsu People’s Republic of China
| | - Taowei Yang
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi Jiangsu People’s Republic of China
| | - Meijuan Xu
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi Jiangsu People’s Republic of China
| | - Huazhong Li
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi Jiangsu People’s Republic of China
| | - Zhenghong Xu
- grid.258151.a 0000000107081323 School of Medicine and Pharmaceuticals Jiangnan University 214122 Wuxi Jiangsu People’s Republic of China
| | - Zhiming Rao
- grid.258151.a 0000000107081323 The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology Jiangnan University 214122 Wuxi Jiangsu People’s Republic of China
- grid.258151.a 0000000107081323 School of Biotechnology Jiangnan University 1800 Lihu Avenue 214122 Wuxi Jiangsu People’s Republic of China
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Zhang X, Yang TW, Lin Q, Xu MJ, Xia HF, Xu ZH, Li HZ, Rao ZM. Isolation and identification of an acetoin high production bacterium that can reverse transform 2,3-butanediol to acetoin at the decline phase of fermentation. World J Microbiol Biotechnol 2011. [DOI: 10.1007/s11274-011-0754-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Lamy-Pitara E, El Mouahid S, Barbier J. Effect of anions on catalytic and electrocatalytic hydrogenations and on the electrocatalytic oxidation and evolution of hydrogen on platinum. Electrochim Acta 2000. [DOI: 10.1016/s0013-4686(00)00522-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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