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Dietz BR, Olszewski NE, Barney BM. Enhanced extracellular ammonium release in the plant endophyte Gluconacetobacter diazotrophicus through genome editing. Microbiol Spectr 2024; 12:e0247823. [PMID: 38038458 PMCID: PMC10783055 DOI: 10.1128/spectrum.02478-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 10/27/2023] [Indexed: 12/02/2023] Open
Abstract
IMPORTANCE Our results demonstrate increased extracellular ammonium release in the endophyte plant growth-promoting bacterium Gluconacetobacter diazotrophicus. Strains were constructed in a manner that leaves no antibiotic markers behind, such that these strains contain no transgenes. Levels of ammonium achieved by cultures of modified G. diazotrophicus strains reached concentrations of approximately 18 mM ammonium, while wild-type G. diazotrophicus remained much lower (below 50 µM). These findings demonstrate a strong potential for further improving the biofertilizer potential of this important microbe.
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Affiliation(s)
- Benjamin R. Dietz
- Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, Minnesota, USA
| | - Neil E. Olszewski
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
| | - Brett M. Barney
- Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, Minnesota, USA
- Biotechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
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Yu G, Duan Q, Cui T, Jiang C, Li X, Li Y, Fu J, Zhang Y, Wang H, Luan J. Development of a bacterial gene transcription activating strategy based on transcriptional activator positive feedback. J Adv Res 2023:S2090-1232(23)00400-9. [PMID: 38123018 DOI: 10.1016/j.jare.2023.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 11/26/2023] [Accepted: 12/16/2023] [Indexed: 12/23/2023] Open
Abstract
INTRODUCTION Transcription of biological nitrogen fixation (nif) genes is activated by the NifA protein which recognizes specific activating sequences upstream of σ54-dependent nif promoters. The large quantities of nitrogenase which can make up 20% of the total proteins in the cell indicates high transcription activating efficiency of NifA and high transcription level of nifHDK nitrogenase genes. OBJECTIVES Development of an efficient gene transcription activating strategy in bacteria based on positive transcription regulatory proteins and their regulating DNA sequences. METHODS We designed a highly efficient gene transcription activating strategy in which the nifA gene was placed directly downstream of its regulating sequences. The NifA protein binds its regulating sequences and stimulates transcription of itself and downstream genes. Overexpressed NifA causes transcription activation by positive reinforcement. RESULTS When this gene transcription activating strategy was used to overexpress NifA in Pseudomonas stutzeri DSM4166 containing the nif gene cluster, the nitrogenase activity was increased by 368 folds which was 16 times higher than that obtained by nifA driven by the strongest endogenous constitutive promoter. When this strategy was used to activate transcription of exogenous biosynthetic genes for the plant auxin indole-3-acetic acid and the antitumor alkaloid pigment prodigiosin in DSM4166, both of them resulted in better performance than the strongest endogenous constitutive promoter and the highest reported productions in heterologous hosts to date. Finally, we demonstrated the universality of this strategy using the positive transcriptional regulator of the psp operon, PspF, in E. coli and the pathway-specific positive transcription regulator of the polyene antibiotic salinomycin biosynthesis, SlnR, in Streptomyces albus. CONCLUSION Many positive transcription regulatory proteins and their regulating DNA sequences have been identified in bacteria. The gene transcription activating strategy developed in this study will have broad applications in molecular biology and biotechnology.
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Affiliation(s)
- Guangle Yu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China
| | - Qiuyue Duan
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China
| | - Tianqi Cui
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China
| | - Chanjuan Jiang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China
| | - Xiaochen Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China
| | - Yutong Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China
| | - Jun Fu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China
| | - Youming Zhang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China
| | - Hailong Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China.
| | - Ji Luan
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, Shandong University, Binhai Rd 72, 266237, Qingdao, Shandong, China.
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