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Park S, Lee S, Kim T, Choi A, Lee S, Kim P. Development strategy of non-GMO organism for increased hemoproteins in Corynebacterium glutamicum: a growth-acceleration-targeted evolution. Bioprocess Biosyst Eng 2024; 47:549-556. [PMID: 38499686 PMCID: PMC11003892 DOI: 10.1007/s00449-024-02986-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 02/13/2024] [Indexed: 03/20/2024]
Abstract
Heme, found in hemoproteins, is a valuable source of iron, an essential mineral. The need for an alternative hemoprotein source has emerged due to the inherent risks of large-scale livestock farming and animal proteins. Corynebacterium glutamicum, regarded for Qualified Presumption of Safety or Generally Recognized as Safe, can biosynthesize hemoproteins. C. glutamicum single-cell protein (SCP) can be a valuable alternative hemoprotein for supplying heme iron without adversely affecting blood fat levels. We constructed the chemostat culture system to increase hemoprotein content in C. glutamicum SCP. Through adaptive evolution, hemoprotein levels could be naturally increased to address oxidative stress resulting from enhanced growth rate. In addition, we used several specific plasmids containing growth-accelerating genes and the hemA promoter to expedite the evolutionary process. Following chemostat culture for 15 days, the plasmid in selected descendants was cured. The evolved strains showed improved specific growth rates from 0.59 h-1 to 0.62 h-1, 20% enhanced resistance to oxidative stress, and increased heme concentration from 12.95 µg/g-DCW to 14.22-15.24 µg/g-DCW. Notably, the putative peptidyl-tRNA hydrolase-based evolved strain manifested the most significant increase (30%) of hemoproteins. This is the first report presenting the potential of a growth-acceleration-targeted evolution (GATE) strategy for developing non-GMO industrial strains with increased bio-product productivity.
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Affiliation(s)
- Sehyeon Park
- Research Group of Novel Food Ingredients for Alternative Proteins, The Catholic University of Korea, Bucheon, Gyeonggi, 14662, Republic of Korea
| | - Seungki Lee
- Department of Biotechnology, The Catholic University of Korea, Bucheon, Gyeonggi, 14662, Republic of Korea
| | - Taeyeon Kim
- Research Group of Novel Food Ingredients for Alternative Proteins, The Catholic University of Korea, Bucheon, Gyeonggi, 14662, Republic of Korea
| | - Ahyoung Choi
- Research Group of Novel Food Ingredients for Alternative Proteins, The Catholic University of Korea, Bucheon, Gyeonggi, 14662, Republic of Korea
| | - Soyeon Lee
- Research Group of Novel Food Ingredients for Alternative Proteins, The Catholic University of Korea, Bucheon, Gyeonggi, 14662, Republic of Korea
| | - Pil Kim
- Research Group of Novel Food Ingredients for Alternative Proteins, The Catholic University of Korea, Bucheon, Gyeonggi, 14662, Republic of Korea.
- Department of Biotechnology, The Catholic University of Korea, Bucheon, Gyeonggi, 14662, Republic of Korea.
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Jiang Z, Guan J, Liu T, Shangguan C, Xu M, Rao Z. The flavohaemoprotein hmp maintains redox homeostasis in response to reactive oxygen and nitrogen species in Corynebacterium glutamicum. Microb Cell Fact 2023; 22:158. [PMID: 37596674 PMCID: PMC10436651 DOI: 10.1186/s12934-023-02160-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 07/25/2023] [Indexed: 08/20/2023] Open
Abstract
BACKGROUND During the production of L-arginine through high dissolved oxygen and nitrogen supply fermentation, the industrial workhorse Corynebacterium glutamicum is exposed to oxidative stress. This generates reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are harmful to the bacteria. To address the issue and to maintain redox homeostasis during fermentation, the flavohaemoprotein (Hmp) was employed. RESULTS The results showed that the overexpression of Hmp led to a decrease in ROS and RNS content by 9.4% and 22.7%, respectively, and improved the survivability of strains. When the strains were treated with H2O2 and NaNO2, the RT-qPCR analysis indicated an up-regulation of ammonium absorption and transporter genes amtB and glnD. Conversely, the deletion of hmp gives rise to the up-regulation of eight oxidative stress-related genes. These findings suggested that hmp is associated with oxidative stress and intracellular nitrogen metabolism genes. Finally, we released the inhibitory effect of ArnR on hmp. The Cc-ΔarnR-hmp strain produced 48.4 g/L L-arginine during batch-feeding fermentation, 34.3% higher than the original strain. CONCLUSIONS This report revealed the influence of dissolved oxygen and nitrogen concentration on reactive species of Corynebacterium glutamicum and the role of the Hmp in coping with oxidative stress. The Hmp first demonstrates related to redox homeostasis and nitrite metabolism, providing a feasible strategy for improving the robustness of strains.
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Affiliation(s)
- Ziqin Jiang
- The Key Laboratory of Industrial Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China
| | - Jingyi Guan
- The Key Laboratory of Industrial Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China
| | - Tingting Liu
- Yantai Shinho Enterprise Foods Co., Ltd, Yantai, 265503, China
| | - Chunyu Shangguan
- The Key Laboratory of Industrial Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China
| | - Meijuan Xu
- The Key Laboratory of Industrial Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China.
| | - Zhiming Rao
- The Key Laboratory of Industrial Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu, 214122, China
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3
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Schmitt I, Meyer F, Krahn I, Henke NA, Peters-Wendisch P, Wendisch VF. From Aquaculture to Aquaculture: Production of the Fish Feed Additive Astaxanthin by Corynebacterium glutamicum Using Aquaculture Sidestream. Molecules 2023; 28:molecules28041996. [PMID: 36838984 PMCID: PMC9958746 DOI: 10.3390/molecules28041996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/31/2023] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
Circular economy holds great potential to minimize the use of finite resources, and reduce waste formation by the creation of closed-loop systems. This also pertains to the utilization of sidestreams in large-scale biotechnological processes. A flexible feedstock concept has been established for the industrially relevant Corynebacterium glutamicum, which naturally synthesizes the yellow C50 carotenoid decaprenoxanthin. In this study, we aimed to use a preprocessed aquaculture sidestream for production of carotenoids, including the fish feed ingredient astaxanthin by C. glutamicum. The addition of a preprocessed aquaculture sidestream to the culture medium did not inhibit growth, obviated the need for addition of several components of the mineral salt's medium, and notably enhanced production of astaxanthin by an engineered C. glutamicum producer strain. Improved astaxanthin production was scaled to 2 L bioreactor fermentations. This strategy to improve astaxanthin production was shown to be transferable to production of several native and non-native carotenoids. Thus, this study provides a proof-of-principle for improving carotenoid production by C. glutamicum upon supplementation of a preprocessed aquaculture sidestream. Moreover, in the case of astaxanthin production it may be a potential component of a circular economy in aquaculture.
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Huang M, Zhu L, Feng L, Zhan L, Zhao Y, Chen X. Reforming Nitrate Metabolism for Enhancing L-Arginine Production in Corynebacterium crenatum Under Oxygen Limitation. Front Microbiol 2022; 13:834311. [PMID: 35356524 PMCID: PMC8959459 DOI: 10.3389/fmicb.2022.834311] [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: 12/13/2021] [Accepted: 02/10/2022] [Indexed: 11/13/2022] Open
Abstract
Various amino acids are widely manufactured using engineered bacteria. It is crucial to keep the dissolved oxygen at a certain level during fermentation, but accompanied by many disadvantages, such as high energy consumption, reactive oxygen species, and risk of phage infections. Thus, anaerobic production of amino acids is worth attempting. Nitrate respiration systems use nitrate as an electron acceptor under anoxic conditions, which is different from the metabolism of fermentation and can produce energy efficiently. Herein, we engineered Corynebacterium crenatum to enhance L-arginine production under anaerobic conditions through strengthening nitrate respiration and reforming nitrogen flux. The construction of mutant strain produced up to 3.84 g/L L-arginine under oxygen limitation with nitrate, and this value was 131.33% higher than that produced by the control strain under limited concentrations of oxygen without nitrate. Results could provide fundamental information for improving L-arginine production by metabolic engineering of C. crenatum under oxygen limitation.
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Affiliation(s)
- Mingzhu Huang
- Department of Life Science, Jiangxi Normal University, Nanchang, China.,National R&D Center for Freshwater Fish Processing, Nanchang, China
| | - Lingfeng Zhu
- Department of Life Science, Jiangxi Normal University, Nanchang, China
| | - Lin Feng
- Department of Life Science, Jiangxi Normal University, Nanchang, China
| | - Li Zhan
- Department of Life Science, Jiangxi Normal University, Nanchang, China
| | - Yue Zhao
- Department of Life Science, Jiangxi Normal University, Nanchang, China
| | - Xuelan Chen
- Department of Life Science, Jiangxi Normal University, Nanchang, China.,National R&D Center for Freshwater Fish Processing, Nanchang, China.,Key Laboratory of Functional Small Organic Molecule of Ministry of Education, Jiangxi Normal University, Nanchang, China
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Ikeyama N, Ohkuma M, Sakamoto M. Stress Response of Mesosutterella multiformis Mediated by Nitrate Reduction. Microorganisms 2020; 8:microorganisms8122003. [PMID: 33333944 PMCID: PMC7765368 DOI: 10.3390/microorganisms8122003] [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: 11/18/2020] [Revised: 12/07/2020] [Accepted: 12/14/2020] [Indexed: 11/25/2022] Open
Abstract
Bacterial stress responses are closely associated with the survival and colonization of anaerobes in the human gut. Mesosutterella multiformis JCM 32464T is a novel member of the family Sutterellaceae, an asaccharolytic bacterium. We previously demonstrated energy generation via heme biosynthesis, which is coupled with nitrate reductase. Here, physiological and morphological changes in M. multiformis induced by exposure to nitrate were investigated. The ability of M. multiformis to reduce nitrate was determined using a colorimetric assay. A unique morphology was observed during nitrate reduction under anaerobic conditions. The association between nitrate concentration and cell size or cellular fatty acid composition was evaluated. Nitrate-induced responses of M. multiformis were compared to those of related species. An increase in cellular filamentation and the ratio of saturated: unsaturated fatty acids was mediated specifically by nitrate. This indicates a decrease in cell fluidity and low leakage. Furthermore, a similar response was not observed in other related species cultured in the presence of nitrate. Hence, the nitrate-induced stress response in new anaerobes such as M. multiformis was demonstrated. The response could also be involved in the conservation of menaquinones and the maximization of nitrate reduction.
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Affiliation(s)
- Nao Ikeyama
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba 305-0074, Ibaraki, Japan
| | - Moriya Ohkuma
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba 305-0074, Ibaraki, Japan
| | - Mitsuo Sakamoto
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba 305-0074, Ibaraki, Japan
- PRIME, Japan Agency for Medical Research and Development (AMED), Tsukuba 305-0074, Ibaraki, Japan
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6
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Nambu T, Wang D, Mashimo C, Maruyama H, Kashiwagi K, Yoshikawa K, Yamamoto K, Okinaga T. Nitric Oxide Donor Modulates a Multispecies Oral Bacterial Community-An In Vitro Study. Microorganisms 2019; 7:microorganisms7090353. [PMID: 31540050 PMCID: PMC6780529 DOI: 10.3390/microorganisms7090353] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 01/10/2023] Open
Abstract
The deterioration of human oral microbiota is known to not only cause oral diseases but also to affect systemic health. Various environmental factors are thought to influence the disruption and restoration of the oral ecosystem. In this study, we focused on the effect of nitric oxide (NO) produced by denitrification and NO synthase enzymes on dental plaque microbiota. Interdental plaques collected from 10 subjects were exposed to NO donor sodium nitroprusside (SNP) and then cultured in a specialized growth medium. Depending on the concentration of exposed SNP, a decrease in α-diversity and a continuous change in β-diversity in the dental plaque community were shown by sequencing bacterial 16S rRNA genes. We also identified eight operational taxonomic units that were significantly altered by NO exposure. Among them, the exposure of NO donors to Fusobacterium nucleatum cells showed a decrease in survival rate consistent with the results of microbiota analysis. Meanwhile, in addition to NO tolerance, an increase in the tetrazolium salt-reducing activity of Campylobacter concisus cells was confirmed by exposure to SNP. This study provides an overview of how oral plaque microbiota shifts with exposure to NO and may contribute to the development of a method for adjusting the balance of the oral microbiome.
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Affiliation(s)
- Takayuki Nambu
- Department of Bacteriology, Osaka Dental University, 8-1, Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
| | - Dan Wang
- Department of Operative Dentistry, Graduate School of Dentistry, Osaka Dental University, 8-1, Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
| | - Chiho Mashimo
- Department of Bacteriology, Osaka Dental University, 8-1, Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
| | - Hugo Maruyama
- Department of Bacteriology, Osaka Dental University, 8-1, Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
| | - Kosuke Kashiwagi
- Department of Fixed Prosthodontics, Osaka Dental University, 8-1, Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
| | - Kazushi Yoshikawa
- Department of Operative Dentistry, Osaka Dental University, 8-1, Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
| | - Kazuyo Yamamoto
- Department of Operative Dentistry, Osaka Dental University, 8-1, Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
| | - Toshinori Okinaga
- Department of Bacteriology, Osaka Dental University, 8-1, Kuzuha-Hanazono, Hirakata, Osaka 573-1121, Japan.
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7
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Kang W, Chai H, Xiang Y, Chen W, Shao Z, He Q. Assessment of low concentration wastewater treatment operations with dewatered alum sludge-based sequencing batch constructed wetland system. Sci Rep 2017; 7:17497. [PMID: 29235527 PMCID: PMC5727494 DOI: 10.1038/s41598-017-17783-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/30/2017] [Indexed: 11/18/2022] Open
Abstract
Competition of volatile fatty acids between anoxic denitrification and anaerobic phosphorus release is prominent. Therefore, low concentration wastewater has restricted effects on nitrogen and phosphorus removal. The purpose of this study is to treat dormitory sewage with a biochemical oxygen demand (BOD) ranging from 50 to 150 mg/L using dewatered alum sludge-based sequencing batch constructed wetland system. Vegetation in the wetland system was chosen to be Phragmites australis. Three parallel cases were carried out to assess impacts due to different hydraulic retention time (HRT) and artificial aeration. The results showed that this system is effective in removing total nitrogen (TN), ammonia nitrogen (NH3-N) and total phosphorus (TP) under different HRT. However, nitrous oxide (N2O) emission poses to be the greatest challenge in the high HRT cases. Artificial aeration could reduce N2O emission but is associated with high operational cost. Results indicate that dewatered alum sludge-based sequencing batch constructed wetland system is a promising bio-measure in the treatment of low concentration wastewater.
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Affiliation(s)
- Wei Kang
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, P.R. China.,National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, 400045, P.R. China
| | - Hongxiang Chai
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, P.R. China. .,National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, 400045, P.R. China.
| | - Yu Xiang
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, P.R. China.,National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, 400045, P.R. China
| | - Wei Chen
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, P.R. China.,National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, 400045, P.R. China
| | - Zhiyu Shao
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, P.R. China.,National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, 400045, P.R. China
| | - Qiang He
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, P.R. China.,National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, 400045, P.R. China
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8
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Robinson JL, Jaslove JM, Murawski AM, Fazen CH, Brynildsen MP. An integrated network analysis reveals that nitric oxide reductase prevents metabolic cycling of nitric oxide by Pseudomonas aeruginosa. Metab Eng 2017; 41:67-81. [PMID: 28363762 DOI: 10.1016/j.ymben.2017.03.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/21/2016] [Accepted: 03/27/2017] [Indexed: 01/08/2023]
Abstract
Nitric oxide (NO) is a chemical weapon within the arsenal of immune cells, but is also generated endogenously by different bacteria. Pseudomonas aeruginosa are pathogens that contain an NO-generating nitrite (NO2-) reductase (NirS), and NO has been shown to influence their virulence. Interestingly, P. aeruginosa also contain NO dioxygenase (Fhp) and nitrate (NO3-) reductases, which together with NirS provide the potential for NO to be metabolically cycled (NO→NO3-→NO2-→NO). Deeper understanding of NO metabolism in P. aeruginosa will increase knowledge of its pathogenesis, and computational models have proven to be useful tools for the quantitative dissection of NO biochemical networks. Here we developed such a model for P. aeruginosa and confirmed its predictive accuracy with measurements of NO, O2, NO2-, and NO3- in mutant cultures devoid of Fhp or NorCB (NO reductase) activity. Using the model, we assessed whether NO was metabolically cycled in aerobic P. aeruginosa cultures. Calculated fluxes indicated a bottleneck at NO3-, which was relieved upon O2 depletion. As cell growth depleted dissolved O2 levels, NO3- was converted to NO2- at near-stoichiometric levels, whereas NO2- consumption did not coincide with NO or NO3- accumulation. Assimilatory NO2- reductase (NirBD) or NorCB activity could have prevented NO cycling, and experiments with ΔnirB, ΔnirS, and ΔnorC showed that NorCB was responsible for loss of flux from the cycle. Collectively, this work provides a computational tool to analyze NO metabolism in P. aeruginosa, and establishes that P. aeruginosa use NorCB to prevent metabolic cycling of NO.
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Affiliation(s)
- Jonathan L Robinson
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Jacob M Jaslove
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Allison M Murawski
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Christopher H Fazen
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Mark P Brynildsen
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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9
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Sawers RG, Falke D, Fischer M. Oxygen and Nitrate Respiration in Streptomyces coelicolor A3(2). Adv Microb Physiol 2016; 68:1-40. [PMID: 27134020 DOI: 10.1016/bs.ampbs.2016.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Streptomyces species belong to the phylum Actinobacteria and can only grow with oxygen as a terminal electron acceptor. Like other members of this phylum, such as corynebacteria and mycobacteria, the aerobic respiratory chain lacks a soluble cytochrome c. It is therefore implicit that direct electron transfer between the cytochrome bc1 and the cytochrome aa3 oxidase complexes occurs. The complex developmental cycle of streptomycetes manifests itself in the production of spores, which germinate in the presence of oxygen into a substrate mycelium that greatly facilitates acquisition of nutrients necessary to support their saprophytic lifestyle in soils. Due to the highly variable oxygen levels in soils, streptomycetes have developed means of surviving long periods of hypoxia or even anaerobiosis but they fail to grow under these conditions. Little to nothing is understood about how they maintain viability under conditions of oxygen limitation. It is assumed that they can utilise a number of different electron acceptors to help them maintain a membrane potential, one of which is nitrate. The model streptomycete remains Streptomyces coelicolor A3(2), and it synthesises three nonredundant respiratory nitrate reductases (Nar). These Nar enzymes are synthesised during different phases of the developmental cycle and they are functional only under oxygen-limiting (<5% oxygen in air) conditions. Nevertheless, the regulation of their synthesis does not appear to be responsive to nitrate and in the case of Nar1, it appears to be developmentally regulated. This review highlights some of the novel aspects of our current, but somewhat limited, knowledge of respiration in these fascinating bacteria.
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Affiliation(s)
- R G Sawers
- Institute for Biology/Microbiology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany.
| | - D Falke
- Institute for Biology/Microbiology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - M Fischer
- Institute for Biology/Microbiology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany
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Development of a potential stationary-phase specific gene expression system by engineering of SigB-dependent cg3141 promoter in Corynebacterium glutamicum. Appl Microbiol Biotechnol 2016; 100:4473-83. [PMID: 26782746 DOI: 10.1007/s00253-016-7297-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 12/27/2015] [Accepted: 12/28/2015] [Indexed: 02/03/2023]
Abstract
Corynebacterium glutamicum is a non-pathogenic, non-sporulating Gram-positive soil bacterium that has been used for the industrial production of various proteins and chemicals. To achieve enhanced and economical production of target molecules, the development of strong auto-inducible promoters is desired, which can be activated without expensive inducers and has significant advantages for industrial-scale use. Here, we developed a stationary-phase gene expression system by engineering a sigma factor B (SigB)-dependent promoter that can be activated during the transition phase between exponential and stationary growth phases in C. glutamicum. First, the inducibilities of three well-known SigB-dependent promoters were examined using super-folder green fluorescent protein as a reporter protein, and we found that promoter of cg3141 (P cg3141 ) exhibited the highest inducibility. Next, a synthetic promoter library was constructed by randomizing the flanking and space regions of P cg3141 , and the stationary-phase promoters exhibiting high strengths were isolated via FACS-based high-throughput screening. The isolated synthetic promoter (P4-N14) showed a 3.5-fold inducibility and up to 20-fold higher strength compared to those of the original cg3141 promoter. Finally, the use of the isolated P4-N14 for fed-batch cultivation was verified with the production of glutathione S-transferase as a model protein in a lab-scale (5-L) bioreactor.
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11
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Anaerobic growth of Corynebacterium glutamicum via mixed-acid fermentation. Appl Environ Microbiol 2015; 81:7496-508. [PMID: 26276118 DOI: 10.1128/aem.02413-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 08/11/2015] [Indexed: 01/01/2023] Open
Abstract
Corynebacterium glutamicum, a model organism in microbial biotechnology, is known to metabolize glucose under oxygen-deprived conditions to l-lactate, succinate, and acetate without significant growth. This property is exploited for efficient production of lactate and succinate. Our detailed analysis revealed that marginal growth takes place under anaerobic conditions with glucose, fructose, sucrose, or ribose as a carbon and energy source but not with gluconate, pyruvate, lactate, propionate, or acetate. Supplementation of glucose minimal medium with tryptone strongly enhanced growth up to a final optical density at 600 nm (OD600) of 12, whereas tryptone alone did not allow growth. Amino acids with a high ATP demand for biosynthesis and amino acids of the glutamate family were particularly important for growth stimulation, indicating ATP limitation and a restricted carbon flux into the oxidative tricarboxylic acid cycle toward 2-oxoglutarate. Anaerobic cultivation in a bioreactor with constant nitrogen flushing disclosed that CO2 is required to achieve maximal growth and that the pH tolerance is reduced compared to that under aerobic conditions, reflecting a decreased capability for pH homeostasis. Continued growth under anaerobic conditions indicated the absence of an oxygen-requiring reaction that is essential for biomass formation. The results provide an improved understanding of the physiology of C. glutamicum under anaerobic conditions.
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