1
|
Yang C, Peng Z, Yang L, Du B, Guo C, Sui S, Wang J, Li J, Wang J, Li N. Design and application of artificial rare L-lysine codons in Corynebacterium glutamicum. Front Bioeng Biotechnol 2023; 11:1194511. [PMID: 37324439 PMCID: PMC10268032 DOI: 10.3389/fbioe.2023.1194511] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 05/16/2023] [Indexed: 06/17/2023] Open
Abstract
Background: L-lysine is widely used in the feed, food, and pharmaceutical industries, and screening for high L-lysine-producing strains has become a key goal for the industry. Methods: We constructed the rare L-lysine codon AAA by corresponding tRNA promoter replacement in C. glutamicum. Additionally, a screening marker related to the intracellular L-lysine content was constructed by converting all L-lysine codons of enhanced green fluorescent protein (EGFP) into the artificial rare codon AAA. The artificial EGFP was then ligated into pEC-XK99E and transformed into competent Corynebacterium glutamicum 23604 cells with the rare L-lysine codon. After atmospheric and room-temperature plasma mutation and induction culture, 55 mutants (0.01% of total cells) with stronger fluorescence were sorted using flow cytometry, and further screened by fermentation in a 96-deep-well plate and 500 mL shaker. Results: The fermentation results showed that the L-lysine production was increased by up to 9.7% in the mutant strains with higher fluorescence intensities, and that the highest screening positive rate was 69%, compared with that in the wild-type strain. Conclusion: The application of artificially constructed rare codons in this study represents an efficient, accurate, and simple method for screening other amino acid-producing microorganisms.
Collapse
Affiliation(s)
- Cuiping Yang
- Department of Biological Engineering, Qilu University of Technology, Jinan, China
| | - Zehao Peng
- Department of Biological Engineering, Qilu University of Technology, Jinan, China
| | - Lu Yang
- Department of Biological Engineering, Qilu University of Technology, Jinan, China
| | - Bowen Du
- Department of Biological Engineering, Qilu University of Technology, Jinan, China
| | | | - Songsen Sui
- Zhucheng Dongxiao Biotechnology Co., Ltd., Zhucheng, China
| | - Jianbin Wang
- Zhucheng Dongxiao Biotechnology Co., Ltd., Zhucheng, China
| | - Junlin Li
- Zhucheng Dongxiao Biotechnology Co., Ltd., Zhucheng, China
| | - Junqing Wang
- Department of Biological Engineering, Qilu University of Technology, Jinan, China
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology, Jinan, China
| | - Nan Li
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| |
Collapse
|
2
|
Wang J, Yang J, Shi G, Li W, Ju Y, Wei L, Liu J, Xu N. Transcriptome profiles of high-lysine adaptation reveal insights into osmotic stress response in Corynebacterium glutamicum. Front Bioeng Biotechnol 2022; 10:933325. [PMID: 36017356 PMCID: PMC9395588 DOI: 10.3389/fbioe.2022.933325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 07/06/2022] [Indexed: 12/05/2022] Open
Abstract
Corynebacterium glutamicum has been widely and effectively used for fermentative production of l-lysine on an industrial scale. However, high-level accumulation of end products inevitably leads to osmotic stress and hinders further increase of l-lysine production. At present, the underlying mechanism by which C. glutamicum cells adapt to high-lysine-induced osmotic stress is still unclear. In this study, we conducted a comparative transcriptomic analysis by RNA-seq to determine gene expression profiles under different high-lysine stress conditions. The results indicated that the increased expression of some metabolic pathways such as sulfur metabolism and specific amino acid biosynthesis might offer favorable benefits for high-lysine adaptation. Functional assays of 18 representative differentially expressed genes showed that the enhanced expression of multiple candidate genes, especially grpE chaperon, conferred high-lysine stress tolerance in C. glutamicum. Moreover, DNA repair component MutT and energy-transducing NADH dehydrogenase Ndh were also found to be important for protecting cells against high-lysine-induced osmotic stress. Taken together, these aforementioned findings provide broader views of transcriptome profiles and promising candidate targets of C. glutamicum for the adaptation of high-lysine stress during fermentation.
Collapse
Affiliation(s)
- Jian Wang
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China
| | - Jian Yang
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China
| | - Guoxin Shi
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China
| | - Weidong Li
- College of Biological and Agricultural Engineering, Jilin University, Changchun, China
| | - Yun Ju
- School of Food Engineering and Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Liang Wei
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Jun Liu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Ning Xu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- *Correspondence: Ning Xu,
| |
Collapse
|
3
|
Toyoda K, Sugaya R, Domon A, Suda M, Hiraga K, Inui M. Identification and Molecular Characterization of the Operon Required for L-Asparagine Utilization in Corynebacterium glutamicum. Microorganisms 2022; 10:1002. [PMID: 35630445 PMCID: PMC9145765 DOI: 10.3390/microorganisms10051002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 04/30/2022] [Accepted: 05/07/2022] [Indexed: 11/25/2022] Open
Abstract
Understanding the metabolic pathways of amino acids and their regulation is important for the rational metabolic engineering of amino acid production. The catabolic pathways of L-asparagine and L-aspartate are composed of transporters for amino acid uptake and asparaginase and aspartase, which are involved in the sequential deamination to fumarate. However, knowledge of the catabolic genes for asparagine in bacteria of the Actinobacteria class has been limited. In this study, we identified and characterized the ans operon required for L-Asn catabolism in Corynebacterium glutamicum R. The operon consisted of genes encoding a transcriptional regulator (AnsR), asparaginase (AnsA2), aspartase (AspA2), and permease (AnsP). The enzymes and permease encoded in the operon were shown to be essential for L-Asn utilization, but another asparaginase, AnsA1, and aspartase, AspA1, were not essential. Expression analysis revealed that the operon was induced in response to extracellular L-Asn and was transcribed as a leaderless mRNA. The DNA-binding assay demonstrated that AnsR acted as a transcriptional repressor of the operon by binding to the inverted repeat at its 5'-end region. The AnsR binding was inhibited by L-Asn. This study provides insights into the functions and regulatory mechanisms of similar operon-like clusters in related bacteria.
Collapse
Affiliation(s)
- Koichi Toyoda
- Research Institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai, Kizugawa 619-0292, Japan; (K.T.); (M.S.); (K.H.)
| | - Riki Sugaya
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan; (R.S.); (A.D.)
| | - Akihiro Domon
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan; (R.S.); (A.D.)
| | - Masako Suda
- Research Institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai, Kizugawa 619-0292, Japan; (K.T.); (M.S.); (K.H.)
| | - Kazumi Hiraga
- Research Institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai, Kizugawa 619-0292, Japan; (K.T.); (M.S.); (K.H.)
| | - Masayuki Inui
- Research Institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai, Kizugawa 619-0292, Japan; (K.T.); (M.S.); (K.H.)
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan; (R.S.); (A.D.)
| |
Collapse
|
4
|
Alrosan M, Tan TC, Koh WY, Easa AM, Gammoh S, Alu'datt MH. Overview of fermentation process: structure-function relationship on protein quality and non-nutritive compounds of plant-based proteins and carbohydrates. Crit Rev Food Sci Nutr 2022; 63:7677-7691. [PMID: 35266840 DOI: 10.1080/10408398.2022.2049200] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Demands for high nutritional value-added food products and plant-based proteins have increased over the last decade, in line with the growth of the human population and consumer health awareness. The quality of the plant-based proteins depends on their digestibility, amino acid content, and residues of non-nutritive compounds, such as phenolic compounds, anti-nutritional compounds, antioxidants, and saponins. The presence of these non-nutritive compounds could have detrimental effects on the quality of the proteins. One of the solutions to address these shortcomings of plant-based proteins is fermentation, whereby enzymes that present naturally in microorganisms used during fermentation are responsible for the cleavage of the bonds between proteins and non-nutritive compounds. This mechanism has pronounced effects on the non-nutritive compounds, resulting in the enhancement of protein digestibility and functional properties of plant-based proteins. We assert that the types of plant-based proteins and microorganisms used during fermentation must be carefully addressed to truly enhance the quality, functional properties, and health functionalities of plant-based proteins.Supplemental data for this article is available online at here. show.
Collapse
Affiliation(s)
- Mohammad Alrosan
- Food Technology Division, School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia
- Faculty of Agriculture, Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid, Jordan
| | - Thuan-Chew Tan
- Food Technology Division, School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Wee Yin Koh
- Faculty of Food Science and Nutrition, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia
| | - Azhar Mat Easa
- Food Technology Division, School of Industrial Technology, Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Sana Gammoh
- Faculty of Agriculture, Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid, Jordan
| | - Muhammad H Alu'datt
- Faculty of Agriculture, Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid, Jordan
| |
Collapse
|
5
|
Kerbs A, Mindt M, Schwardmann L, Wendisch VF. Sustainable Production of N-methylphenylalanine by Reductive Methylamination of Phenylpyruvate Using Engineered Corynebacterium glutamicum. Microorganisms 2021; 9:microorganisms9040824. [PMID: 33924554 PMCID: PMC8070496 DOI: 10.3390/microorganisms9040824] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 12/17/2022] Open
Abstract
N-alkylated amino acids occur widely in nature and can also be found in bioactive secondary metabolites such as the glycopeptide antibiotic vancomycin and the immunosuppressant cyclosporine A. To meet the demand for N-alkylated amino acids, they are currently produced chemically; however, these approaches often lack enantiopurity, show low product yields and require toxic reagents. Fermentative routes to N-alkylated amino acids like N-methyl-l-alanine or N-methylantranilate, a precursor of acridone alkaloids, have been established using engineered Corynebacterium glutamicum, which has been used for the industrial production of amino acids for decades. Here, we describe metabolic engineering of C. glutamicum for de novo production of N-methylphenylalanine based on reductive methylamination of phenylpyruvate. Pseudomonas putida Δ-1-piperideine-2-carboxylate reductase DpkA containing the amino acid exchanges P262A and M141L showed comparable catalytic efficiencies with phenylpyruvate and pyruvate, whereas the wild-type enzyme preferred the latter substrate over the former. Deletion of the anthranilate synthase genes trpEG and of the genes encoding branched-chain amino acid aminotransferase IlvE and phenylalanine aminotransferase AroT in a strain engineered to overproduce anthranilate abolished biosynthesis of l-tryptophan and l-phenylalanine to accumulate phenylpyruvate. Upon heterologous expression of DpkAP262A,M141L, N-methylphenylalanine production resulted upon addition of monomethylamine to the medium. In glucose-based minimal medium, an N-methylphenylalanine titer of 0.73 ± 0.05 g L−1, a volumetric productivity of 0.01 g L−1 h−1 and a yield of 0.052 g g−1 glucose were reached. When xylose isomerase gene xylA from Xanthomonas campestris and the endogenous xylulokinase gene xylB were expressed in addition, xylose as sole carbon source supported production of N-methylphenylalanine to a titer of 0.6 ± 0.04 g L−1 with a volumetric productivity of 0.008 g L−1 h−1 and a yield of 0.05 g g−1 xylose. Thus, a fermentative route to sustainable production of N-methylphenylalanine by recombinant C. glutamicum has been established.
Collapse
Affiliation(s)
- Anastasia Kerbs
- Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, 33615 Bielefeld, Germany; (A.K.); (L.S.)
| | - Melanie Mindt
- BU Bioscience, Wagenigen University and Research, 6700AA Wageningen, The Netherlands;
| | - Lynn Schwardmann
- Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, 33615 Bielefeld, Germany; (A.K.); (L.S.)
| | - Volker F. Wendisch
- Genetics of Prokaryotes, Faculty of Biology and CeBiTec, Bielefeld University, 33615 Bielefeld, Germany; (A.K.); (L.S.)
- Correspondence: ; Tel.: +49-521-106-5611
| |
Collapse
|
6
|
Xiao J, Wang D, Wang L, Jiang Y, Xue L, Sui S, Wang J, Guo C, Wang R, Wang J, Li N, Fan H, Lv M. Increasing L-lysine production in Corynebacterium glutamicum by engineering amino acid transporters. Amino Acids 2020; 52:1363-1374. [PMID: 33021685 DOI: 10.1007/s00726-020-02893-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 09/17/2020] [Indexed: 12/28/2022]
Abstract
Corynebacterium glutamicum has a long and successful history in the biotechnological production of L-lysine. Besides the adjustment of metabolic pathways, intracellular and extracellular transport systems are critical for the cellular metabolism of L-lysine or its by-products. Here, three amino acid transmembrane transporters, namely, GluE, BrnE/BrnF, and LysP, which are widely present in C. glutamicum strains, were each investigated by gene knockout. In comparison with that in the wild-type strain, the yield of L-lysine increased by 9.0%, 12.3%, and 10.0% after the deletion of the gluE, brnE/brnF, and lysP genes, respectively, in C. glutamicum 23,604. Moreover, the amount of by-product amino acids decreased significantly when the gluE and brnE/brnF genes were deleted. It was also demonstrated that there was no effect on the growth of the strain when the gluE or lysP gene was deleted, whereas the biomass of C. glutamicum WL1702 (ΔbrnE/ΔbrnF) in the fermentation medium was significantly reduced in comparison with that of the wild type. These results also provide useful information for enhancing the production of L-lysine or other amino acids by C. glutamicum.
Collapse
Affiliation(s)
- Jing Xiao
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Datao Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Lei Wang
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, People's Republic of China
| | - Yanjun Jiang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Le Xue
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Songsen Sui
- Zhucheng Dongxiao Biotechnology Co., Ltd, Xinxing Town, Zhucheng, 262200, Shandong, People's Republic of China
| | - Jianbin Wang
- Zhucheng Dongxiao Biotechnology Co., Ltd, Xinxing Town, Zhucheng, 262200, Shandong, People's Republic of China
| | - Chuanzhuang Guo
- Zhucheng Dongxiao Biotechnology Co., Ltd, Xinxing Town, Zhucheng, 262200, Shandong, People's Republic of China
| | - Ruiming Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Junqing Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China.
| | - Nan Li
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
| | - Han Fan
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Maocui Lv
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| |
Collapse
|
7
|
Sato N, Kishida M, Nakano M, Hirata Y, Tanaka T. Metabolic Engineering of Shikimic Acid-Producing Corynebacterium glutamicum From Glucose and Cellobiose Retaining Its Phosphotransferase System Function and Pyruvate Kinase Activities. Front Bioeng Biotechnol 2020; 8:569406. [PMID: 33015020 PMCID: PMC7511668 DOI: 10.3389/fbioe.2020.569406] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 08/19/2020] [Indexed: 01/23/2023] Open
Abstract
The production of aromatic compounds by microbial production is a promising and sustainable approach for producing biomolecules for various applications. We describe the metabolic engineering of Corynebacterium glutamicum to increase its production of shikimic acid. Shikimic acid and its precursor-consuming pathways were blocked by the deletion of the shikimate kinase, 3-dehydroshikimate dehydratase, shikimate dehydratase, and dihydroxyacetone phosphate phosphatase genes. Plasmid-based expression of shikimate pathway genes revealed that 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase, encoded by aroG, and DHQ synthase, encoded by aroB, are key enzymes for shikimic acid production in C. glutamicum. We constructed a C. glutamicum strain with aroG, aroB and aroE3 integrated. This strain produced 13.1 g/L of shikimic acid from 50 g/L of glucose, a yield of 0.26 g-shikimic acid/g-glucose, and retained both its phosphotransferase system and its pyruvate kinase activity. We also endowed β-glucosidase secreting ability to this strain. When cellobiose was used as a carbon source, the strain produced shikimic acid at 13.8 g/L with the yield of 0.25 g-shikimic acid/g-glucose (1 g of cellobiose corresponds to 1.1 g of glucose). These results demonstrate the feasibility of producing shikimic acid and its derivatives using an engineered C. glutamicum strain from cellobiose as well as glucose.
Collapse
Affiliation(s)
- Naoki Sato
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Mayumi Kishida
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Mariko Nakano
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Yuuki Hirata
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Tsutomu Tanaka
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| |
Collapse
|
8
|
An economically and environmentally acceptable synthesis of chiral drug intermediate l-pipecolic acid from biomass-derived lysine via artificially engineered microbes. ACTA ACUST UNITED AC 2018; 45:405-415. [DOI: 10.1007/s10295-018-2044-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/29/2018] [Indexed: 12/29/2022]
Abstract
Abstract
Deficiency in petroleum resources and increasing environmental concerns have pushed a bio-based economy to be built, employing a highly reproducible, metal contaminant free, sustainable and green biomanufacturing method. Here, a chiral drug intermediate l-pipecolic acid has been synthesized from biomass-derived lysine. This artificial bioconversion system involves the coexpression of four functional genes, which encode l-lysine α-oxidase from Scomber japonicus, glucose dehydrogenase from Bacillus subtilis, Δ1-piperideine-2-carboxylase reductase from Pseudomonas putida, and lysine permease from Escherichia coli. Besides, a lysine degradation enzyme has been knocked out to strengthen the process in this microbe. The overexpression of LysP improved the l-pipecolic acid titer about 1.6-folds compared to the control. This engineered microbial factory showed the highest l-pipecolic acid production of 46.7 g/L reported to date and a higher productivity of 2.41 g/L h and a yield of 0.89 g/g. This biotechnological l-pipecolic acid production is a simple, economic, and green technology to replace the presently used chemical synthesis.
Collapse
|
9
|
Adaptive laboratory evolution of Corynebacterium glutamicum towards higher growth rates on glucose minimal medium. Sci Rep 2017; 7:16780. [PMID: 29196644 PMCID: PMC5711897 DOI: 10.1038/s41598-017-17014-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/17/2017] [Indexed: 12/18/2022] Open
Abstract
In this work, we performed a comparative adaptive laboratory evolution experiment of the important biotechnological platform strain Corynebacterium glutamicum ATCC 13032 and its prophage-free variant MB001 towards improved growth rates on glucose minimal medium. Both strains displayed a comparable adaptation behavior and no significant differences in genomic rearrangements and mutation frequencies. Remarkably, a significant fitness leap by about 20% was observed for both strains already after 100 generations. Isolated top clones (UBw and UBm) showed an about 26% increased growth rate on glucose minimal medium. Genome sequencing of evolved clones and populations resulted in the identification of key mutations in pyk (pyruvate kinase), fruK (1-phosphofructokinase) and corA encoding a Mg2+ importer. The reintegration of selected pyk and fruK mutations resulted in an increased glucose consumption rate and ptsG expression causative for the accelerated growth on glucose minimal medium, whereas corA mutations improved growth under Mg2+ limiting conditions. Overall, this study resulted in the identification of causative key mutations improving the growth of C. glutamicum on glucose. These identified mutational hot spots as well as the two evolved top strains, UBw and UBm, represent promising targets for future metabolic engineering approaches.
Collapse
|