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Yuan S, Xu C, Jin M, Xian M, Liu W. Synergistic improvement of cinnamylamine production by metabolic regulation. J Biol Eng 2023; 17:14. [PMID: 36823535 PMCID: PMC9948449 DOI: 10.1186/s13036-023-00334-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 02/15/2023] [Indexed: 02/25/2023] Open
Abstract
BACKGROUND Aromatic primary amines (APAs) are key intermediates in the chemical industry with numerous applications. Efficient and mild biocatalytic synthesis is an excellent complement to traditional chemical synthesis. Our lab previously reported a whole-cell catalytic system for the synthesis of APAs catalyzed by carboxylic acid reductase from Neurospora crassa (ncCAR) and ω-transaminase from Ochrobactrum anthropi (OATA). However, the accumulation of toxic intermediates (aromatic aldehydes) during biocatalytic synthesis affected yields of APAs due to metabolic imbalance. RESULTS In this work, the biocatalytic synthesis of APAs (taking cinnamylamine as an example) was metabolically regulated by the overexpression or knockout of five native global transcription factors (TFs), the overexpression of eight native resistance genes, and optimization of promoters. Transcriptome analysis showed that knockout of the TF arcA increased the fluxes of NADPH and ATP in E. coli, while the rate of pyruvate metabolism was accelerated. In addition, the genes related to stress and detoxification were upregulated with the overexpression of resistance gene marA, which reduced the NADPH level in E. coli. Then, the expression level of soluble OATA increased by promoter optimization. Overall, arcA and marA could regulate the catalytic rate of NADPH- dependent ncCAR, while arcA and optimized promoter could regulate the catalytic rate of OATA. Lastly, the cinnamylamine yield of the best metabolically engineered strain S020 was increased to 90% (9 mM, 1.2 g/L), and the accumulation of cinnamaldehyde was below 0.9 mM. This work reported the highest production of cinnamylamine by biocatalytic synthesis. CONCLUSION This regulatory process provides a common strategy for regulating the biocatalytic synthesis of other APAs. Being entirely biocatalytic, our one-pot procedure provides considerable advantages in terms of environmental and safety impacts over reported chemical methods.
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Affiliation(s)
- Shan Yuan
- grid.458500.c0000 0004 1806 7609CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101 Shandong P.R. China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Chao Xu
- grid.458500.c0000 0004 1806 7609CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101 Shandong P.R. China
| | - Miaomiao Jin
- grid.458500.c0000 0004 1806 7609CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101 Shandong P.R. China
| | - Mo Xian
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101, Shandong, P.R. China.
| | - Wei Liu
- CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101, Shandong, P.R. China.
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2
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Self-sufficient whole-cell biocatalysis for 3-(aminomethyl) pyridine synthesis. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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3
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The ArcAB Two-Component System: Function in Metabolism, Redox Control, and Infection. Microbiol Mol Biol Rev 2022; 86:e0011021. [PMID: 35442087 PMCID: PMC9199408 DOI: 10.1128/mmbr.00110-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
ArcAB, also known as the Arc system, is a member of the two-component system family of bacterial transcriptional regulators and is composed of sensor kinase ArcB and response regulator ArcA. In this review, we describe the structure and function of these proteins and assess the state of the literature regarding ArcAB as a sensor of oxygen consumption. The bacterial quinone pool is the primary modulator of ArcAB activity, but questions remain for how this regulation occurs. This review highlights the role of quinones and their oxidation state in activating and deactivating ArcB and compares competing models of the regulatory mechanism. The cellular processes linked to ArcAB regulation of central metabolic pathways and potential interactions of the Arc system with other regulatory systems are also reviewed. Recent evidence for the function of ArcAB under aerobic conditions is challenging the long-standing characterization of this system as strictly an anaerobic global regulator, and the support for additional ArcAB functionality in this context is explored. Lastly, ArcAB-controlled cellular processes with relevance to infection are assessed.
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4
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Yang H, Jia X, Han Y. Microbial redox coenzyme engineering and applications in biosynthesis. Trends Microbiol 2022; 30:318-321. [DOI: 10.1016/j.tim.2022.01.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/15/2022] [Accepted: 01/17/2022] [Indexed: 12/24/2022]
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5
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Cao Y, Xu Y, Li Q, Rose RS, Abrahams I, Jones CR, Sheriff TS. Corrosion Inhibition and Disinfection of Heating and Cooling Water Systems Using In Situ Generated Hydrogen Peroxide. NEW J CHEM 2022. [DOI: 10.1039/d2nj03806d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aqueous solutions of MnCl2·4H2O and Tiron (disodium 4,5-dihydroxy-1,3-benzenedisulfonate) rapidly remove dioxygen (O2) from aqueous solution at a rate of ~20 mg∙ L -1 min-1 with turnover frequencies (TOFs) of up...
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6
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Wang S, Tian R, Liu B, Wang H, Liu J, Li C, Li M, Evivie SE, Li B. Effects of carbon concentration, oxygen, and controlled pH on the engineering strain Lactiplantibacillus casei E1 in the production of bioethanol from sugarcane molasses. AMB Express 2021; 11:95. [PMID: 34176008 PMCID: PMC8236424 DOI: 10.1186/s13568-021-01257-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 06/16/2021] [Indexed: 01/28/2023] Open
Abstract
Sugarcane molasses are considered a potential source for bioethanol's commercial production because of its availability and low market price. It contains high concentrations of fermentable sugars that can be directly metabolized by microbial fermentation. Heterofermentative lactic acid bacteria, especially Lactiplantibacillus casei, have a high potential to be a biocatalyst in ethanol production that they are characterized by strong abilities of carbohydrate metabolism, ethanol synthesis, and high alcohol tolerance. This study aimed to evaluate the feasibility of producing ethanol by Lactiplantibacillus casei used the ethanologen engineering strain L. casei E1 as a starter culture and cane molasses as substrate medium. The effects of environmental factors on the metabolism of L. casei E1 were analyzed by high-performance liquid chromatography (HPLC) system, and the gene expression of key enzymes in carbon source metabolism was detected using quantitative real-time PCR (RT-qPCR). Results showed that the strain could grow well, ferment sugar quickly in cane molasses. By fermenting this bacterium anaerobically at 37 °C for 36 h incubation in 5 °BX molasses when the fermenter's pH was controlled at 6.0, ethanol yield reached 13.77 g/L, and carbohydrate utilization percentage was 78.60%. RT-qPCR results verified the strain preferentially ferment glucose and fructose of molasses to ethanol at the molecular level. In addition, the metabolism of sugars, especially fructose, would be inhibited by elevating acidity. Our findings support the theoretical basis for exploring Lactic acid bacteria as a starter culture for converting sugarcane molasses into ethanol.
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Affiliation(s)
- Song Wang
- Food College, Northeast Agricultural University, Harbin, 150030, China
- Shandong Yuwang Ecological Food Industry Co., Ltd, Dezhou, 251200, Shandong, China
| | - Ran Tian
- Food College, Northeast Agricultural University, Harbin, 150030, China
| | - Buwei Liu
- Food College, Northeast Agricultural University, Harbin, 150030, China
| | - Hongcai Wang
- Shandong Yuwang Ecological Food Industry Co., Ltd, Dezhou, 251200, Shandong, China
| | - Jun Liu
- Shandong Yuwang Ecological Food Industry Co., Ltd, Dezhou, 251200, Shandong, China
| | - Chenghui Li
- Shandong Yuwang Ecological Food Industry Co., Ltd, Dezhou, 251200, Shandong, China
| | - Mingyue Li
- Shandong Yuwang Ecological Food Industry Co., Ltd, Dezhou, 251200, Shandong, China
| | - Smith Etareri Evivie
- Food College, Northeast Agricultural University, Harbin, 150030, China
- Department of Animal Science, Faculty of Agriculture, University of Benin, Benin City, 300001, Nigeria
- Department of Food Science and Human Nutrition, Faculty of Agriculture, University of Benin, Benin City, 300001, Nigeria
| | - Bailiang Li
- Food College, Northeast Agricultural University, Harbin, 150030, China.
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Nochino N, Toya Y, Shimizu H. Transcription Factor ArcA is a Flux Sensor for the Oxygen Consumption Rate in Escherichia coli. Biotechnol J 2020; 15:e1900353. [PMID: 32383263 DOI: 10.1002/biot.201900353] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/30/2020] [Indexed: 12/24/2022]
Abstract
Oxygen supply is one of the major factors determining the metabolic state in microorganisms, and it affects the productivity of various compounds during bioproduction. In Escherichia coli (E. coli), the expression levels of numerous metabolic genes are regulated by transcription factors in response to changes in environmental oxygen conditions. Even at a same dissolved oxygen concentration, the amount of available oxygen changes depending on the oxygen transfer coefficient. However, it is not known whether E. coli is able to sense differences in the oxygen consumption rate. Therefore, the present study, is focused on the role of the transcription factor ArcA in the oxygen response of E. coli and investigated the relationship between ArcA activity and the oxygen consumption rate. To evaluate the activity of ArcA, a sensor plasmid expressing fluorescent protein under the control of the icd promoter, which is regulated by ArcA, is designed. E. coli containing the sensor plasmid is grown in continuous cultures with different oxygen supplies under different dilution rates. Although there is no correlation between ArcA activity and dissolved oxygen concentration, a strong negative correlation between ArcA activity and the specific oxygen consumption rate (R2 > 0.93) is observed.
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Affiliation(s)
- Naoya Nochino
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshihiro Toya
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hiroshi Shimizu
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
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8
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Matsuoka Y, Kurata H. Computer-Aided Rational Design of Efficient NADPH Production System by Escherichia coli pgi Mutant Using a Mixture of Glucose and Xylose. Front Bioeng Biotechnol 2020; 8:277. [PMID: 32318559 PMCID: PMC7154054 DOI: 10.3389/fbioe.2020.00277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/16/2020] [Indexed: 12/02/2022] Open
Abstract
Lignocellulosic biomass can be hydrolyzed into two major sugars of glucose and xylose, and thus the strategy for the efficient consumption of both sugars is highly desirable. NADPH is the essential molecule for the production of industrially important value-added chemicals, and thus its availability is quite important. Escherichia coli mutant lacking the pgi gene encoding phosphoglucose isomerase (Pgi) has been preferentially used to overproduce the NADPH. However, there exists a disadvantage that the cell growth rate becomes low for the mutant grown on glucose. This limits the efficient NADPH production, and therefore, it is quite important to investigate how addition of different carbon source such as xylose (other than glucose) effectively improves the NADPH production. In this study, we have developed a kinetic model to propose an efficient NADPH production system using E. coli pgi-knockout mutant with a mixture of glucose and xylose. The proposed system adds xylose to glucose medium to recover the suppressed growth of the pgi mutant, and determines the xylose content to maximize the NADPH productivity. Finally, we have designed a mevalonate (MVA) production system by implementing ArcA overexpression into the pgi-knockout mutant using a mixture of glucose and xylose. In addition to NADPH overproduction, the accumulation of acetyl-CoA (AcCoA) is necessary for the efficient MVA production. In the present study, therefore, we considered to overexpress ArcA, where ArcA overexpression suppresses the TCA cycle, causing the overflow of AcCoA, a precursor of MVA. We predicted the xylose content that maximizes the MVA production. This approach demonstrates the possibility of a great progress in the computer-aided rational design of the microbial cell factories for useful metabolite production.
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Affiliation(s)
- Yu Matsuoka
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Japan
| | - Hiroyuki Kurata
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Iizuka, Japan.,Biomedical Informatics R&D Center, Kyushu Institute of Technology, Iizuka, Japan
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9
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Effect of dissolved oxygen on L-methionine production from glycerol by Escherichia coli W3110BL using metabolic flux analysis method. J Ind Microbiol Biotechnol 2020; 47:287-297. [PMID: 32052230 DOI: 10.1007/s10295-020-02264-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 01/30/2020] [Indexed: 12/15/2022]
Abstract
L-Methionine is an essential amino acid in humans, which plays an important role in the synthesis of some important amino acids and proteins. In this work, metabolic flux of batch fermentation of L-methionine with recombinant Escherichia coli W3110BL was analyzed using the flux balance analysis method, which estimated the intracellular flux distributions under different dissolved oxygen conditions. The results revealed the producing L-methionine flux of 4.8 mmol/(g cell·h) [based on the glycerol uptake flux of 100 mmol/(g cell·h)] was obtained at 30% dissolved oxygen level which was higher than that of other dissolved oxygen levels. The carbon fluxes for synthesizing L-methionine were mainly obtained from the pathway of phosphoenolpyruvate to oxaloacetic acid [15.6 mmol/(g cell·h)] but not from the TCA cycle. Hence, increasing the flow from phosphoenolpyruvate to oxaloacetic acid by enhancing the enzyme activity of phosphoenolpyruvate carboxylase might be conducive to the production of L-methionine. Additionally, pentose phosphate pathway could provide a large amount of reducing power NADPH for the synthesis of amino acids and the flux could increase from 41 mmol/(g cell·h) to 51 mmol/(g cell·h) when changing the dissolved oxygen levels, thus meeting the requirement of NADPH for L-methionine production and biomass synthesis. Therefore, the following modification of the strains should based on the improvement of the key pathway and the NAD(P)/NAD(P)H metabolism.
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10
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Kurata H. Self-replenishment cycles generate a threshold response. Sci Rep 2019; 9:17139. [PMID: 31748624 PMCID: PMC6868230 DOI: 10.1038/s41598-019-53589-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 11/02/2019] [Indexed: 11/10/2022] Open
Abstract
Many metabolic cycles, including the tricarboxylic acid cycle, glyoxylate cycle, Calvin cycle, urea cycle, coenzyme recycling, and substrate cycles, are well known to catabolize and anabolize different metabolites for efficient energy and mass conversion. In terms of stoichiometric structure, this study explicitly identifies two types of metabolic cycles. One is the well-known, elementary cycle that converts multiple substrates into different products and recycles one of the products as a substrate, where the recycled substrate is supplied from the outside to run the cycle. The other is the self-replenishment cycle that merges multiple substrates into two or multiple identical products and reuses one of the products as a substrate. The substrates are autonomously supplied within the cycle. This study first defines the self-replenishment cycles that many scientists have overlooked despite its functional importance. Theoretical analysis has revealed the design principle of the self-replenishment cycle that presents a threshold response without any bistability nor cooperativity. To verify the principle, three detailed kinetic models of self-replenishment cycles embedded in an E. coli metabolic system were simulated. They presented the threshold response or digital switch-like function that steeply shift metabolic status.
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Affiliation(s)
- Hiroyuki Kurata
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Fukuoka, Japan. .,Biomedical Informatics R&D Center, Kyushu Institute of Technology, Fukuoka, Japan.
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11
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Ding Z, Fang Y, Zhu L, Wang J, Wang X. Deletion of arcA, iclR, and tdcC in Escherichia coli to improve l-threonine production. Biotechnol Appl Biochem 2019; 66:794-807. [PMID: 31177569 DOI: 10.1002/bab.1789] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 06/06/2019] [Indexed: 11/06/2022]
Abstract
l-Threonine is an important amino acid supplemented in food, medicine, or feed. Starting from glucose, l-threonine production in Escherichia coli involves the glycolysis, TCA cycle, and the l-threonine biosynthetic pathway. In this study, how the l-threonine production in an l-threonine producing E. coli TWF001 is controlled by the three regulators ArcA, Cra, and IclR, which control the expression of genes involved in the glycolysis and TCA cycle, has been investigated. Ten mutant strains were constructed from TWF001 by different combinations of deletion or overexpression of arcA, cra, iclR, and tdcC. l-Threonine production was increased in the mutants TWF015 (ΔarcAΔcra), TWF016 (ΔarcAPcra::Ptrc), TWF017 (ΔarcAΔiclR), TWF018 (ΔarcAΔiclRΔtdcC), and TWF019 (ΔarcAΔcraΔiclRΔtdcC). Among these mutant strains, the highest l-threonine production (26.0 g/L) was obtained in TWF018, which was a 109.7% increase compared with the control TWF001. In addition, TWF018 could consume glucose more efficiently than TWF001 and produce less acetate. The results suggest that deletion of arcA, iclR, and tdcC could efficiently increase l-threonine production in E. coli.
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Affiliation(s)
- Zhixiang Ding
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Yu Fang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Lifei Zhu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Jianli Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, People's Republic of China
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12
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Goto S, Suzuki N, Matsumoto K, Taguchi S, Tanaka K, Matsusaki H. Enhancement of lactate fraction in poly(lactate-co-3-hydroxybutyrate) synthesized by Escherichia coli harboring the D-lactate dehydrogenase gene from Lactobacillus acetotolerans HT. J GEN APPL MICROBIOL 2019; 65:204-208. [PMID: 30700650 DOI: 10.2323/jgam.2018.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
For enhancing the lactate (LA) fraction of poly(lactate-co-3-hydroxybutyrate)s [P(LA-co-3HB)s], an exogenous D-lactate dehydrogenase gene (ldhD) was introduced into Escherichia coli. Recombinant strains of E. coli DH5α, LS5218, and XL1-Blue harboring the ldhD gene from Lactobacillus acetotolerans HT, together with polyhydroxyalkanoate (PHA)-biosynthetic genes containing a lactate-polymerizing enzyme (modified PHA synthase) gene, accumulated the P(LA-co-3HB) copolymer from glucose under microaerobic conditions (100 strokes/min). The LA fraction of copolymers synthesized in the strains of DH5α, LS5218, and XL1-Blue were 19.8, 15.7, and 28.5 mol%, respectively, which were higher than those of the strains without the ldhD gene (<6.7 mol% of LA units). Introduction of the exogenous ldhD gene into E. coli strains resulted in an enhanced LA fraction in P(LA-co-3HB)s.
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Affiliation(s)
- Saki Goto
- Department of Food and Health Sciences, Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
| | - Naoyuki Suzuki
- Department of Biological and Environmental Chemistry, Faculty of Humanity-Oriented Science and Engineering, Kindai University
| | - Ken'ichiro Matsumoto
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University
| | - Seiichi Taguchi
- Department of Chemistry for Life Sciences and Agriculture, Faculty of Life Sciences, Tokyo University of Agriculture
| | - Kenji Tanaka
- Department of Biological and Environmental Chemistry, Faculty of Humanity-Oriented Science and Engineering, Kindai University
| | - Hiromi Matsusaki
- Department of Food and Health Sciences, Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
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13
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Chen J, Tang JN, Hu KL, Zhao YY, Tang C. The production characteristics of volatile organic compounds and their relation to growth status of Staphylococcus aureus in milk environment. J Dairy Sci 2018; 101:4983-4991. [PMID: 29550124 DOI: 10.3168/jds.2017-13629] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 12/02/2017] [Indexed: 01/22/2023]
Abstract
In our previous research, 3-methyl-butanal and 3-methyl-butanoic acid were identified as representative and specific volatile organic compounds released by Staphylococcus aureus in broth. In this study, we explored the production of the 2 volatiles and their correlation to Staph. aureus growth in milk under different conditions. We found significant correlations between the production of 3-methyl-butanoic acid and cell counts of 5 Staph. aureus strains in sterile milk, and there were no obvious differences for its production among 5 tested strains. The intensities of the 2 volatiles were similar and positively correlated with bacterial counts in cultures at 25°C and 37°C despite delayed production of volatiles at 25°C; however, neither compound could be detected at 4°C. The production of 3-methyl-butanoic acid was strongly correlated with growth of Staph. aureus mixed with Streptococcus agalactiae, Escherichia coli O157:H7, and Shigella flexneri, whereas correlations for 3-methyl-butanal were not statistically significant. Compared with the monoculture of Staph. aureus, in mixed cultures, production of 3-methyl-butanal was decreased and that of 3-methyl-butanoic acid was comparatively higher. In pasteurized and raw milks, production of 3-methyl-butanoic acid was correlated with growth of Staph. aureus, and 3-methyl-butanoic acid could be detected when Staph. aureus populations reached 106 to 107 cfu/mL in pasteurized milk and 105 to 106 cfu/mL in raw milk; the correlations for 3-methyl-butanal were not statistically significant. Our results suggest that 3-methyl-butanoic acid is a more suitable marker for high counts of Staph. aureus in milk, whereas 3-methyl-butanal is a transient metabolite and easily depressed by environmental factors.
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Affiliation(s)
- J Chen
- College of Life Science and Technology, Southwest University for Nationalities (Southwest Minzu University), Chengdu, China, 610041
| | - J N Tang
- College of Life Science and Technology, Southwest University for Nationalities (Southwest Minzu University), Chengdu, China, 610041.
| | - K L Hu
- College of Life Science and Technology, Southwest University for Nationalities (Southwest Minzu University), Chengdu, China, 610041
| | - Y Y Zhao
- College of Life Science and Technology, Southwest University for Nationalities (Southwest Minzu University), Chengdu, China, 610041
| | - C Tang
- College of Life Science and Technology, Southwest University for Nationalities (Southwest Minzu University), Chengdu, China, 610041
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14
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Improved kinetic model of Escherichia coli central carbon metabolism in batch and continuous cultures. J Biosci Bioeng 2018; 125:251-257. [DOI: 10.1016/j.jbiosc.2017.09.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 09/01/2017] [Accepted: 09/16/2017] [Indexed: 11/21/2022]
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15
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