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Li S, Wang N, Li X. Enhancement of poly‑γ‑L‑diaminobutanoic acid production in Bacillus pumilus by repeated pH shocks. Bioprocess Biosyst Eng 2024:10.1007/s00449-024-03050-z. [PMID: 38904716 DOI: 10.1007/s00449-024-03050-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 06/17/2024] [Indexed: 06/22/2024]
Abstract
This study investigated the effect of pH on poly-γ-L-diaminobutanoic acid (γ-PAB) production by Bacillus pumilus in batch fermentation. In the natural fermentation where pH was not controlled, pH decreased from initial 7.0 to 3.0 in 18 h and γ-PAB production was 428.6 mg/L. In the pH-controlled fermentation, B. pumilus tended to proliferation at higher pH, while γ-PAB synthesis was favorable at lower pH, in which the optimal pH for γ-PAB production was 4.2, and γ-PAB yield reached 2284.5 mg/L. Adopting a pH shock strategy which lasted 9 h in the pre-fermentation phase, biomass (OD600) and γ-PAB yield of B. pumilus were obtained as 61.3 and 2794.6 mg/L, respectively, which were 10.8% and 22.4% higher than those in batch fermentation without pH shock. Subsequent fermentation of repeated pH shocks showed that a further higher productivity could be achieved, in which the final OD600 reached 65.1, and γ-PAB production reached as high as 3482.3 mg/L, which were increased by 6.2% and 17.1% compared with those in single pH shock, respectively. This study demonstrated that B. pumilus can synthesize more γ-PAB at suboptimal pH and provided a novel approach to regulate γ-PAB synthesis.
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Affiliation(s)
- Shu Li
- Marine College, Shandong University, Weihai, 264209, Shandong, China.
| | - Nan Wang
- Food and Drug Inspection, Testing Institute at Weihai, Weihai, 264210, Shandong, China
| | - Xiaoting Li
- Key Laboratory of Modern Marine Ranching Technology of Weihai, Weihai, 264209, Shandong, China
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2
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WANG H, WANG L, FAN K, PAN G. Tetracycline natural products: discovery, biosynthesis and engineering. Chin J Nat Med 2022; 20:773-794. [DOI: 10.1016/s1875-5364(22)60224-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Indexed: 11/03/2022]
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3
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Huang R, Liu H, Zhao W, Wang S, Wang S, Cai J, Yang C. AdpA, a developmental regulator, promotes ε-poly-l-lysine biosynthesis in Streptomyces albulus. Microb Cell Fact 2022; 21:60. [PMID: 35397580 PMCID: PMC8994273 DOI: 10.1186/s12934-022-01785-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 03/31/2022] [Indexed: 12/01/2022] Open
Abstract
Background AdpA is a global regulator of morphological differentiation and secondary metabolism in Streptomyces, but the regulatory roles of the Streptomyces AdpA family on the biosynthesis of the natural product ε-poly-l-lysine (ε-PL) remain unidentified, and few studies have focused on increasing the production of ε-PL by manipulating transcription factors in Streptomyces. Results In this study, we revealed the regulatory roles of different AdpA homologs in ε-PL biosynthesis and morphological differentiation and effectively promoted ε-PL production and sporulation in Streptomycesalbulus NK660 by heterologously expressing adpA from S.neyagawaensis NRRLB-3092 (adpASn). First, we identified a novel AdpA homolog named AdpASa in S.albulus NK660 and characterized its function as an activator of ε-PL biosynthesis and morphological differentiation. Subsequently, four heterologous AdpA homologs were selected to investigate their phylogenetic relationships and regulatory roles in S.albulus, and AdpASn was demonstrated to have the strongest ability to promote both ε-PL production and sporulation among these five AdpA proteins. The ε-PL yield of S.albulus heterologously expressing adpASn was approximately 3.6-fold higher than that of the control strain. Finally, we clarified the mechanism of AdpASn in enhancing ε-PL biosynthesis and its effect on ε-PL polymerization degree using real-time quantitative PCR, microscale thermophoresis and MALDI-TOF–MS. AdpASn was purified, and its seven direct targets, zwf, tal, pyk2, pta, ack, pepc and a transketolase gene (DC74_2409), were identified, suggesting that AdpASn may cause the redistribution of metabolic flux in central metabolism pathways, which subsequently provides more carbon skeletons and ATP for ε-PL biosynthesis in S.albulus. Conclusions Here, we characterized the positive regulatory roles of Streptomyces AdpA homologs in ε-PL biosynthesis and their effects on morphological differentiation and reported for the first time that AdpASn promotes ε-PL biosynthesis by affecting the transcription of its target genes in central metabolism pathways. These findings supply valuable insights into the regulatory roles of the Streptomyces AdpA family on ε-PL biosynthesis and morphological differentiation and suggest that AdpASn may be an effective global regulator for enhanced production of ε-PL and other valuable secondary metabolites in Streptomyces. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-022-01785-6.
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Zong G, Fu J, Zhang P, Zhang W, Xu Y, Cao G, Zhang R. Use of elicitors to enhance or activate the antibiotic production in streptomyces. Crit Rev Biotechnol 2021; 42:1260-1283. [PMID: 34706600 DOI: 10.1080/07388551.2021.1987856] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Streptomyces is the largest and most significant genus of Actinobacteria, comprising 961 species. These Gram-positive bacteria produce many versatile and important bioactive compounds; of these, antibiotics, specifically the enhancement or activation of their production, have received extensive research attention. Recently, various biotic and abiotic elicitors have been reported to modify the antibiotic metabolism of Streptomyces, which promotes the production of new antibiotics and bioactive metabolites for improvement in the yields of endogenous products. However, some elicitors that obviously contribute to secondary metabolite production have not yet received sufficient attention. In this study, we have reviewed the functions and mechanisms of chemicals, novel microbial metabolic elicitors, microbial interactions, enzymes, enzyme inhibitors, environmental factors, and novel combination methods regarding antibiotic production in Streptomyces. This review has aimed to identify potentially valuable elicitors for stimulating the production of latent antibiotics or enhancing the synthesis of subsistent antibiotics in Streptomyces. Future applications and challenges in the discovery of new antibiotics and enhancement of existing antibiotic production using elicitors are discussed.
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Affiliation(s)
- Gongli Zong
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.,Biomedical Sciences College & Shandong Medicinal Biotechnology Centre, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, China
| | - Jiafang Fu
- Biomedical Sciences College & Shandong Medicinal Biotechnology Centre, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, China
| | - Peipei Zhang
- Biomedical Sciences College & Shandong Medicinal Biotechnology Centre, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, China
| | - Wenchi Zhang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yan Xu
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China
| | - Guangxiang Cao
- Biomedical Sciences College & Shandong Medicinal Biotechnology Centre, Shandong First Medical University & Shandong Academy of Medical Sciences, Ji'nan, China
| | - Rongzhen Zhang
- Key Laboratory of Industrial Biotechnology of Ministry of Education & School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China
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Yang Y, Sun Q, Liu Y, Yin H, Yang W, Wang Y, Liu Y, Li Y, Pang S, Liu W, Zhang Q, Yuan F, Qiu S, Li J, Wang X, Fan K, Wang W, Li Z, Yin S. Development of a pyrF-based counterselectable system for targeted gene deletion in Streptomyces rimosus. J Zhejiang Univ Sci B 2021; 22:383-396. [PMID: 33973420 DOI: 10.1631/jzus.b2000606] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Streptomyces produces many valuable and important biomolecules with clinical and pharmaceutical applications. The development of simple and highly efficient gene editing tools for genetic modification of Streptomyces is highly desirable. In this study, we developed a screening system for targeted gene knockout using a uracil auxotrophic host (ΔpyrF) resistant to the highly toxic uracil analog of 5-fluoroorotic acid (5-FOA) converted by PyrF, and a non-replicative vector pKC1132-pyrF carrying the complemented pyrF gene coding for orotidine-5'-phosphate decarboxylase. The pyrF gene acts as a positive selection and counterselection marker for recombinants during genetic modifications. Single-crossover homologous integration mutants were selected on minimal medium without uracil by reintroducing pyrF along with pKC1132-pyrF into the genome of the mutant ΔpyrF at the targeted locus. Double-crossover recombinants were generated, from which the pyrF gene, plasmid backbone, and targeted gene were excised through homologous recombination exchange. These recombinants were rapidly screened by the counterselection agent, 5-FOA. We demonstrated the feasibility and advantage of using this pyrF-based screening system through deleting the otcR gene, which encodes the cluster-situated regulator that directly activates oxytetracycline biosynthesis in Streptomyces rimosus M4018. This system provides a new genetic tool for investigating the genetic characteristics of Streptomyces species.
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Affiliation(s)
- Yiying Yang
- School of Life Sciences, North China University of Science and Technology, Tangshan 063210, China
| | - Qingqing Sun
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yang Liu
- School of Life Sciences, North China University of Science and Technology, Tangshan 063210, China
| | - Hanzhi Yin
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Wenping Yang
- School of Life Sciences, North China University of Science and Technology, Tangshan 063210, China
| | - Yang Wang
- School of Life Sciences, North China University of Science and Technology, Tangshan 063210, China
| | - Ying Liu
- School of Life Sciences, North China University of Science and Technology, Tangshan 063210, China
| | - Yuxian Li
- School of Life Sciences, North China University of Science and Technology, Tangshan 063210, China
| | - Shen Pang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Wenxi Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qian Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Fang Yuan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shiwen Qiu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jiong Li
- Shengxue Dacheng Pharmaceutical Co., Ltd., Shijiazhuang 051430, China
| | - Xuefeng Wang
- Shengxue Dacheng Pharmaceutical Co., Ltd., Shijiazhuang 051430, China
| | - Keqiang Fan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Weishan Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zilong Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Shouliang Yin
- School of Life Sciences, North China University of Science and Technology, Tangshan 063210, China. ,
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6
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Yang W, Kong L, Wang Q, Deng Z, You D. Metabolic engineering of a methyltransferase for production of drug precursors demecycline and demeclocycline in Streptomyces aureofaciens. Synth Syst Biotechnol 2020; 5:121-130. [PMID: 32637665 PMCID: PMC7320239 DOI: 10.1016/j.synbio.2020.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 11/25/2022] Open
Abstract
Demecycline (DMTC) and demeclocycline (DMCTC) are C6-demethylated derivatives of tetracycline (TC) and chlortetracycline (CTC), respectively. They are precursors of minocycline and tigecycline, which showed remarkable bioactivity against TC-resistant bacteria and have been used clinically for decades. In order to biosynthesize drug precursors DMTC and DMCTC, the function of a possible C-methyltransferase encoding gene ctcK was studied systematically in the CTC high-yielding industrial strain Streptomyces aureofaciens F3. The ΔctcK mutant accumulated two new products, which were turned out to be DMTC and DMCTC. Meanwhile, time-course analysis of the fermentation products detected the epimers of DMTC and DMCTC transformed spontaneously. Finally, an engineering strain with higher productivity of DMCTC was constructed by deleting ctcK and overexpressing ctcP of three extra copies simultaneously. Construction of these two engineering strains not only served as a successful example of synthesizing required products through metabolic engineering, but also provided original strains for following elaborate engineering to synthesize more effective tetracycline derivatives.
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Affiliation(s)
- Weinan Yang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Lingxin Kong
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Qing Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Delin You
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China
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Yang T, Yang K, Chen Y, Fan K. Characterization of a Bi-directional Promoter OtrRp Involved in Oxytetracycline Biosynthesis. Curr Microbiol 2019; 76:1264-1269. [PMID: 31410507 DOI: 10.1007/s00284-019-01753-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/31/2019] [Accepted: 08/05/2019] [Indexed: 10/26/2022]
Abstract
Previous studies identified a MarR (multiple antibiotic resistance regulator) family transcription factor OtrR in the oxytetracycline biosynthetic gene cluster, which regulated the expression of an efflux pump OtrB. The genes otrB and otrR were divergent arranged and the inter-ORF (open reading frame) region between the two genes contained the promoter otrBp. In this study, we demonstrated that the reverse complementary sequence of otrBp contained the promoter of otrR, and its activity was also repressed by OtrR by sharing the same operator otrO within otrBp, and allosteric regulated by oxytetracycline. Our findings offered a solid base for the synthetic biological application of the bi-direction promoter in controlling two elements at the same time using only one signal molecule.
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Affiliation(s)
- Tongjian Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Keqian Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yihua Chen
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Keqiang Fan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
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8
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Increased flux through the TCA cycle enhances bacitracin production by Bacillus licheniformis DW2. Appl Microbiol Biotechnol 2018; 102:6935-6946. [PMID: 29911294 DOI: 10.1007/s00253-018-9133-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 05/07/2018] [Accepted: 05/23/2018] [Indexed: 11/27/2022]
Abstract
The dodecapeptide antibiotic bacitracin, produced by several strains of Bacillus licheniformis and Bacillus subtilis, is widely used as an antibacterial animal feed additive. Several genetic strategies were explored to enhance its production. The availability of building block amino acids for bacitracin production was found to play an important role in its synthesis. In this study, the TCA cycle in the industrial strain B. licheniformis DW2 was strengthened by overexpression of the key enzymes citrate synthase and isocitrate dehydrogenase (ICDH). As the central metabolic pathway, the TCA cycle is a major source for energy supply and intermediates for anabolism. By enhancing flux through the TCA cycle, more energy and precursors were generated for amino acid biosynthesis and uptake, resulting in enlarged intracellular pool of bacitracin-containing amino acids for bacitracin production. This study unveiled the metabolic responses of the increased TCA cycle flux in B. licheniformis and provided a novel strategy for enhancing bacitracin production.
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9
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Huang Y, Zhang X, Zhao C, Zhuang X, Zhu L, Guo C, Song Y. Improvement of Spinosad Production upon Utilization of Oils and Manipulation of β-Oxidation in a High-Producing Saccharopolyspora spinosa Strain. J Mol Microbiol Biotechnol 2018; 28:53-64. [PMID: 29730661 DOI: 10.1159/000487854] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 02/20/2018] [Indexed: 11/19/2022] Open
Abstract
Spinosad, a member of polyketide-derived macrolides produced in the actinomycete Saccharopolyspora spinosa, has been developed as a broad-spectrum and effective insecticide. The β-oxidation pathway could be an important source of building blocks for the biosynthesis of spinosad, thus the effect of vegetable oils on the production of spinosad in a high-yield strain was investigated. The spinosad production increased significantly with the addition of strawberry seed oil (511.64 mg/L) and camellia oil (520.07 mg/L) compared to the control group without oil (285.76 mg/L) and soybean oil group (398.11 mg/L). It also revealed that the addition of oils would affect the expression of genes involved in fatty acid metabolism, precursor supply, and oxidative stress. The genetically engineered strain, in which fadD1 and fadE genes of Streptomyces coelicolor were inserted, produced spinosad up to 784.72 mg/L in the medium containing camellia oil, while a higher spinosad production level (843.40 mg/L) was detected with the addition of 0.01 mM of thiourea.
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Affiliation(s)
- Ying Huang
- Key Laboratory of Soil Microbiology, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xiaolin Zhang
- Academy of State Administration of Grain, Beijing, China
| | - Chen Zhao
- Academy of State Administration of Grain, Beijing, China
| | - Xuhui Zhuang
- Academy of State Administration of Grain, Beijing, China
| | - Lin Zhu
- Academy of State Administration of Grain, Beijing, China
| | - Chao Guo
- Academy of State Administration of Grain, Beijing, China
| | - Yuan Song
- Key Laboratory of Soil Microbiology, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
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10
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Feng R, Li J, Zhang A. Improving isobutanol titers in Saccharomyces cerevisiae with over-expressing NADPH-specific glucose-6-phosphate dehydrogenase (Zwf1). ANN MICROBIOL 2017. [DOI: 10.1007/s13213-017-1304-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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Jia H, Zhang L, Wang T, Han J, Tang H, Zhang L. Development of a CRISPR/Cas9-mediated gene-editing tool in Streptomyces rimosus. Microbiology (Reading) 2017; 163:1148-1155. [DOI: 10.1099/mic.0.000501] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Haiyan Jia
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province; Key Laboratory of Microbial Diversity Research and Application of Hebei Province; Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding 071002, PR China
| | - Longmei Zhang
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province; Key Laboratory of Microbial Diversity Research and Application of Hebei Province; Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding 071002, PR China
| | - Tongtong Wang
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province; Key Laboratory of Microbial Diversity Research and Application of Hebei Province; Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding 071002, PR China
| | - Jin Han
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province; Key Laboratory of Microbial Diversity Research and Application of Hebei Province; Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding 071002, PR China
| | - Hui Tang
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province; Key Laboratory of Microbial Diversity Research and Application of Hebei Province; Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding 071002, PR China
| | - Liping Zhang
- Engineering Laboratory of Microbial Breeding and Preservation of Hebei Province; Key Laboratory of Microbial Diversity Research and Application of Hebei Province; Key Discipline of Biological Engineering of Hebei Province, College of Life Sciences, Hebei University, Baoding 071002, PR China
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Improvement of oxytetracycline production mediated via cooperation of resistance genes in Streptomyces rimosus. SCIENCE CHINA-LIFE SCIENCES 2017; 60:992-999. [PMID: 28755296 DOI: 10.1007/s11427-017-9121-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Accepted: 05/12/2017] [Indexed: 01/15/2023]
Abstract
Increasing the self-resistance levels of Streptomyces is an effective strategy to improve the production of antibiotics. To increase the oxytetracycline (OTC) production in Streptomyces rimosus, we investigated the cooperative effect of three co-overexpressing OTC resistance genes: one gene encodes a ribosomal protection protein (otrA) and the other two express efflux proteins (otrB and otrC). Results indicated that combinational overexpression of otrA, otrB, and otrC (MKABC) exerted a synergetic effect. OTC production increased by 179% in the recombinant strain compared with that of the wild-type strain M4018. The resistance level to OTC was increased by approximately two-fold relative to the parental strain, thereby indicating that applying the cooperative effect of self-resistance genes is useful to improve OTC production. Furthermore, the previously identified cluster-situated activator OtcR was overexpressed in MKABC in constructing the recombinant strain MKRABC; such strain can produce OTC of approximately 7.49 g L-1, which represents an increase of 19% in comparison with that of the OtcR-overexpressing strain alone. Our work showed that the cooperative overexpression of self-resistance genes is a promising strategy to enhance the antibiotics production in Streptomyces.
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A novel approach to improve poly-γ-glutamic acid production by NADPH Regeneration in Bacillus licheniformis WX-02. Sci Rep 2017; 7:43404. [PMID: 28230096 PMCID: PMC5322528 DOI: 10.1038/srep43404] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 01/24/2017] [Indexed: 01/15/2023] Open
Abstract
Poly-γ-glutamic acid (γ-PGA) is an important biochemical product with a variety of applications. This work reports a novel approach to improve γ-PGA through over expression of key enzymes in cofactor NADPH generating process for NADPH pool. Six genes encoding the key enzymes in NADPH generation were over-expressed in the γ-PGA producing strain B. licheniformis WX-02. Among various recombinants, the strain over-expressing zwf gene (coding for glucose-6-phosphate dehydrogenase), WX-zwf, produced the highest γ-PGA concentration (9.13 g/L), 35% improvement compared to the control strain WX-pHY300. However, the growth rates and glucose uptake rates of the mutant WX-zwf were decreased. The transcriptional levels of the genes pgsB and pgsC responsible for γ-PGA biosynthesis were increased by 8.21- and 5.26-fold, respectively. The Zwf activity of the zwf over expression strain increased by 9.28-fold, which led to the improvement of the NADPH generation, and decrease of accumulation of by-products acetoin and 2,3-butanediol. Collectively, these results demonstrated that NADPH generation via over-expression of Zwf is as an effective strategy to improve the γ-PGA production in B. licheniformis.
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Bilyk O, Luzhetskyy A. Metabolic engineering of natural product biosynthesis in actinobacteria. Curr Opin Biotechnol 2016; 42:98-107. [DOI: 10.1016/j.copbio.2016.03.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/03/2016] [Accepted: 03/11/2016] [Indexed: 11/25/2022]
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15
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Yin S, Li Z, Wang X, Wang H, Jia X, Ai G, Bai Z, Shi M, Yuan F, Liu T, Wang W, Yang K. Heterologous expression of oxytetracycline biosynthetic gene cluster in Streptomyces venezuelae WVR2006 to improve production level and to alter fermentation process. Appl Microbiol Biotechnol 2016; 100:10563-10572. [PMID: 27709288 DOI: 10.1007/s00253-016-7873-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/28/2016] [Accepted: 09/16/2016] [Indexed: 02/06/2023]
Abstract
Heterologous expression is an important strategy to activate biosynthetic gene clusters of secondary metabolites. Here, it is employed to activate and manipulate the oxytetracycline (OTC) gene cluster and to alter OTC fermentation process. To achieve these goals, a fast-growing heterologous host Streptomyces venezuelae WVR2006 was rationally selected among several potential hosts. It shows rapid and dispersed growth and intrinsic high resistance to OTC. By manipulating the expression of two cluster-situated regulators (CSR) OtcR and OtrR and precursor supply, the OTC production level was significantly increased in this heterologous host from 75 to 431 mg/l only in 48 h, a level comparable to the native producer Streptomyces rimosus M4018 in 8 days. This work shows that S. venezuelae WVR2006 is a promising chassis for the production of secondary metabolites, and the engineered heterologous OTC producer has the potential to completely alter the fermentation process of OTC production.
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Affiliation(s)
- Shouliang Yin
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing, 100101, People's Republic of China
| | - Zilong Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing, 100101, People's Republic of China
| | - Xuefeng Wang
- Shengxue Dacheng Pharmaceutical Co., Ltd., Shijiazhuang, 051430, Hebei, People's Republic of China
| | - Huizhuan Wang
- Shengxue Dacheng Pharmaceutical Co., Ltd., Shijiazhuang, 051430, Hebei, People's Republic of China
| | - Xiaole Jia
- Shengxue Dacheng Pharmaceutical Co., Ltd., Shijiazhuang, 051430, Hebei, People's Republic of China
| | - Guomin Ai
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing, 100101, People's Republic of China
| | - Zishang Bai
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing, 100101, People's Republic of China
| | - Mingxin Shi
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing, 100101, People's Republic of China
| | - Fang Yuan
- Shengxue Dacheng Pharmaceutical Co., Ltd., Shijiazhuang, 051430, Hebei, People's Republic of China
| | - Tiejun Liu
- Shengxue Dacheng Pharmaceutical Co., Ltd., Shijiazhuang, 051430, Hebei, People's Republic of China
| | - Weishan Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing, 100101, People's Republic of China.
| | - Keqian Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing, 100101, People's Republic of China.
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Zhang MM, Wang Y, Ang EL, Zhao H. Engineering microbial hosts for production of bacterial natural products. Nat Prod Rep 2016; 33:963-87. [PMID: 27072804 PMCID: PMC4963277 DOI: 10.1039/c6np00017g] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Covering up to end 2015Microbial fermentation provides an attractive alternative to chemical synthesis for the production of structurally complex natural products. In most cases, however, production titers are low and need to be improved for compound characterization and/or commercial production. Owing to advances in functional genomics and genetic engineering technologies, microbial hosts can be engineered to overproduce a desired natural product, greatly accelerating the traditionally time-consuming strain improvement process. This review covers recent developments and challenges in the engineering of native and heterologous microbial hosts for the production of bacterial natural products, focusing on the genetic tools and strategies for strain improvement. Special emphasis is placed on bioactive secondary metabolites from actinomycetes. The considerations for the choice of host systems will also be discussed in this review.
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Affiliation(s)
- Mingzi M Zhang
- Metabolic Engineering Research Laboratory, Science and Engineering Institutes, Agency for Science, Technology and Research, Singapore
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17
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Improvement of chloramphenicol production in Streptomyces venezuelae ATCC 10712 by overexpression of the aroB and aroK genes catalysing steps in the shikimate pathway. Antonie van Leeuwenhoek 2015; 109:379-88. [DOI: 10.1007/s10482-015-0640-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 12/18/2015] [Indexed: 01/13/2023]
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18
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Zeng X, Chen XS, Gao Y, Ren XD, Wang L, Mao ZG. Continuously high reactive oxygen species generation decreased the specific ϵ-poly- l -lysine formation rate in fed-batch fermentation using glucose and glycerol as a mixed carbon source. Process Biochem 2015. [DOI: 10.1016/j.procbio.2015.09.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Yin S, Wang W, Wang X, Zhu Y, Jia X, Li S, Yuan F, Zhang Y, Yang K. Identification of a cluster-situated activator of oxytetracycline biosynthesis and manipulation of its expression for improved oxytetracycline production in Streptomyces rimosus. Microb Cell Fact 2015; 14:46. [PMID: 25886456 PMCID: PMC4393881 DOI: 10.1186/s12934-015-0231-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/25/2015] [Indexed: 11/10/2022] Open
Abstract
Background Oxytetracycline (OTC) is a broad-spectrum antibiotic commercially produced by Streptomyces rimosus. Despite its importance, little is known about the regulation of OTC biosynthesis, which hampered any effort to improve OTC production via engineering regulatory genes. Results A gene encoding a Streptomyces antibiotic regulatory protein (SARP) was discovered immediately adjacent to the otrB gene of oxy cluster in S. rimosus and designated otcR. Deletion and complementation of otcR abolished or restored OTC production, respectively, indicating that otcR encodes an essential activator of OTC biosynthesis. Then, the predicted consensus SARP-binding sequences were extracted from the promoter regions of oxy cluster. Transcriptional analysis in a heterologous GFP reporter system demonstrated that OtcR directly activated the transcription of five oxy promoters in E. coli, further mutational analysis of a SARP-binding sequence of oxyI promoter proved that OtcR directly interacted with the consensus repeats. Therefore, otcR was chosen as an engineering target, OTC production was significantly increased by overexpression of otcR as tandem copies each under the control of strong SF14 promoter. Conclusions A SARP activator, OtcR, was identified in oxy cluster of S. rimosus; it was shown to directly activate five promoters from oxy cluster. Overexpression of otcR at an appropriate level dramatically increased OTC production by 6.49 times compared to the parental strain, thus demonstrating the great potential of manipulating OtcR to improve the yield of OTC production. Electronic supplementary material The online version of this article (doi:10.1186/s12934-015-0231-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shouliang Yin
- Department of Environmental and Biological Engineering, School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), D11 Xueyuan Road, Haidian District, Beijing, 100083, People's Republic of China.
| | - Weishan Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, 100101, People's Republic of China.
| | - Xuefeng Wang
- Shengxue Dacheng Pharmaceutical Co., Ltd, 50 Shengxue Road, Shijiazhuang, 051430, Hebei, People's Republic of China.
| | - Yaxin Zhu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, 100101, People's Republic of China.
| | - Xiaole Jia
- Shengxue Dacheng Pharmaceutical Co., Ltd, 50 Shengxue Road, Shijiazhuang, 051430, Hebei, People's Republic of China.
| | - Shanshan Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, 100101, People's Republic of China.
| | - Fang Yuan
- Shengxue Dacheng Pharmaceutical Co., Ltd, 50 Shengxue Road, Shijiazhuang, 051430, Hebei, People's Republic of China.
| | - Yuxiu Zhang
- Department of Environmental and Biological Engineering, School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), D11 Xueyuan Road, Haidian District, Beijing, 100083, People's Republic of China.
| | - Keqian Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, 100101, People's Republic of China.
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Singh V, Mani I, Chaudhary DK. Metabolic Engineering of Microorganisms for Biosynthesis of Antibiotics. SYSTEMS AND SYNTHETIC BIOLOGY 2015. [DOI: 10.1007/978-94-017-9514-2_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Zeng X, Chen XS, Ren XD, Liu QR, Wang L, Sun QX, Tang L, Mao ZG. Insights into the Role of Glucose and Glycerol as a Mixed Carbon Source in the Improvement of ε-Poly-l-Lysine Productivity. Appl Biochem Biotechnol 2014; 173:2211-24. [DOI: 10.1007/s12010-014-1026-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 06/19/2014] [Indexed: 10/25/2022]
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22
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Qi H, Zhao S, Wen J, Chen Y, Jia X. Analysis of ascomycin production enhanced by shikimic acid resistance and addition in Streptomyces hygroscopicus var. ascomyceticus. Biochem Eng J 2014. [DOI: 10.1016/j.bej.2013.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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23
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A Micromachined Pressure Sensor with Integrated Resonator Operating at Atmospheric Pressure. SENSORS 2013. [PMCID: PMC3892843 DOI: 10.3390/s131217006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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24
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Zabala D, Braña AF, Flórez AB, Salas JA, Méndez C. Engineering precursor metabolite pools for increasing production of antitumor mithramycins in Streptomyces argillaceus. Metab Eng 2013; 20:187-97. [PMID: 24148183 DOI: 10.1016/j.ymben.2013.10.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 07/24/2013] [Accepted: 10/03/2013] [Indexed: 11/19/2022]
Abstract
Mithramycin (MTM) is a polyketide antitumor compound produced by Streptomyces argillaceus constituted by a tricyclic aglycone with two aliphatic side chains, a trisaccharide and a disaccharide chain. The biosynthesis of the polyketide aglycone is initiated by the condensation of ten malonyl-CoA units to render a carbon chain that is modified to a tetracyclic intermediate and sequentially glycosylated by five deoxysugars originated from glucose-1-phosphate. Further oxidation and reduction render the final compound. We aimed to increase the precursor supply of malonyl-CoA and/or glucose-1-phosphate in S. argillaceus to enhance MTM production. We have shown that by overexpressing either the S. coelicolor phosphoglucomutase gene pgm or the acetyl-CoA carboxylase ovmGIH genes from the oviedomycin biosynthesis gene cluster in S. argillaceus, we were able to increase the intracellular pool of glucose-1-phosphate and malonyl-CoA, respectively. Moreover, we have cloned the S. argillaceus ADP-glucose pyrophosphorylase gene glgCa and the acyl-CoA:diacylglycerol acyltransferase gene aftAa, and we showed that by inactivating them, an increase of the intracellular concentration of glucose-1-phosphate/glucose-6-phosphate and malonyl-CoA/acetyl-CoA was observed, respectively. Each individual modification resulted in an enhancement of MTM production but the highest production level was obtained by combining all strategies together. In addition, some of these strategies were successfully applied to increase production of four MTM derivatives with improved pharmacological properties: demycarosyl-mithramycin, demycarosyl-3D-β-D-digitoxosyl-mithramycin, mithramycin SK and mithramycin SDK.
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Affiliation(s)
- Daniel Zabala
- Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, Oviedo, Spain
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Chaudhary AK, Dhakal D, Sohng JK. An insight into the "-omics" based engineering of streptomycetes for secondary metabolite overproduction. BIOMED RESEARCH INTERNATIONAL 2013; 2013:968518. [PMID: 24078931 PMCID: PMC3775442 DOI: 10.1155/2013/968518] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 07/26/2013] [Accepted: 07/28/2013] [Indexed: 11/25/2022]
Abstract
Microorganisms produce a range of chemical substances representing a vast diversity of fascinating molecular architectures not available in any other system. Among them, Streptomyces are frequently used to produce useful enzymes and a wide variety of secondary metabolites with potential biological activities. Streptomyces are preferred over other microorganisms for producing more than half of the clinically useful naturally originating pharmaceuticals. However, these compounds are usually produced in very low amounts (or not at all) under typical laboratory conditions. Despite the superiority of Streptomyces, they still lack well documented genetic information and a large number of in-depth molecular biological tools for strain improvement. Previous attempts to produce high yielding strains required selection of the genetic material through classical mutagenesis for commercial production of secondary metabolites, optimizing culture conditions, and random selection. However, a profound effect on the strategy for strain development has occurred with the recent advancement of whole-genome sequencing, systems biology, and genetic engineering. In this review, we demonstrate a few of the major issues related to the potential of "-omics" technology (genomics, transcriptomics, proteomics, and metabolomics) for improving streptomycetes as an intelligent chemical factory for enhancing the production of useful bioactive compounds.
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Affiliation(s)
- Amit Kumar Chaudhary
- Department of Pharmaceutical Engineering, Institute of Biomolecule Reconstruction, SunMoon University, 100 Kalsan-ri, Tangjeongmyeon, Asan-si, Chungnam 336-708, Republic of Korea
| | - Dipesh Dhakal
- Department of Pharmaceutical Engineering, Institute of Biomolecule Reconstruction, SunMoon University, 100 Kalsan-ri, Tangjeongmyeon, Asan-si, Chungnam 336-708, Republic of Korea
| | - Jae Kyung Sohng
- Department of Pharmaceutical Engineering, Institute of Biomolecule Reconstruction, SunMoon University, 100 Kalsan-ri, Tangjeongmyeon, Asan-si, Chungnam 336-708, Republic of Korea
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Deciphering and engineering of the final step halogenase for improved chlortetracycline biosynthesis in industrial Streptomyces aureofaciens. Metab Eng 2013; 19:69-78. [DOI: 10.1016/j.ymben.2013.06.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/27/2013] [Accepted: 06/14/2013] [Indexed: 11/21/2022]
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Formation, regeneration, and transformation of protoplasts of Streptomyces diastatochromogenes 1628. Folia Microbiol (Praha) 2013; 59:93-7. [DOI: 10.1007/s12223-013-0271-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 07/08/2013] [Indexed: 10/26/2022]
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28
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Liu G, Chater KF, Chandra G, Niu G, Tan H. Molecular regulation of antibiotic biosynthesis in streptomyces. Microbiol Mol Biol Rev 2013; 77:112-43. [PMID: 23471619 PMCID: PMC3591988 DOI: 10.1128/mmbr.00054-12] [Citation(s) in RCA: 496] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Streptomycetes are the most abundant source of antibiotics. Typically, each species produces several antibiotics, with the profile being species specific. Streptomyces coelicolor, the model species, produces at least five different antibiotics. We review the regulation of antibiotic biosynthesis in S. coelicolor and other, nonmodel streptomycetes in the light of recent studies. The biosynthesis of each antibiotic is specified by a large gene cluster, usually including regulatory genes (cluster-situated regulators [CSRs]). These are the main point of connection with a plethora of generally conserved regulatory systems that monitor the organism's physiology, developmental state, population density, and environment to determine the onset and level of production of each antibiotic. Some CSRs may also be sensitive to the levels of different kinds of ligands, including products of the pathway itself, products of other antibiotic pathways in the same organism, and specialized regulatory small molecules such as gamma-butyrolactones. These interactions can result in self-reinforcing feed-forward circuitry and complex cross talk between pathways. The physiological signals and regulatory mechanisms may be of practical importance for the activation of the many cryptic secondary metabolic gene cluster pathways revealed by recent sequencing of numerous Streptomyces genomes.
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Affiliation(s)
- Gang Liu
- State Key Laboratory of Microbial Resources
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Keith F. Chater
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
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Investigation of proteomic responses of Streptomyces lydicus to pitching ratios for improving streptolydigin production. BIOTECHNOL BIOPROC E 2012. [DOI: 10.1007/s12257-012-0173-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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30
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Oxytetracycline biosynthesis improvement in Streptomyces rimosus following duplication of minimal PKS genes. Enzyme Microb Technol 2012; 50:318-24. [PMID: 22500899 DOI: 10.1016/j.enzmictec.2012.03.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 03/08/2012] [Accepted: 03/08/2012] [Indexed: 11/19/2022]
Abstract
Oxytetracycline (OTC) is a widely used antibiotic, which is commercially produced by Streptomyces rimosus. The type II minimal polyketide synthases (minimal PKS) genes of the oxytetracycline biosynthesis cluster in S. rimosus, consisting of oxyA, oxyB and oxyC, are involved in catalyzing 19-C chain building by the condensation of eight malonyl-CoA groups to form the starting polyketide. This study aimed to investigate the effects of overexpression of the minimal PKS gene in a model S. rimosus strain (M4018) and in an industrial overproducer (SR16) by introduction of a second copy of the gene into the chromosome. Increased levels of oxyA, oxyB and oxyC gene transcription were monitored using reverse transcription quantitative real-time PCR. Overexpression of the minimal PKS gene elicited retardation of cell growth and a significant improvement in OTC production in corresponding mutants (approximately 51.2% and 32.9% in M4018 and SR16 mutants respectively). These data indicate that the minimal PKS plays an important role in carbon flux redirection from cell growth pathways to OTC biosynthesis pathways.
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