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Sparviero S, Dicke MD, Rosch TM, Castillo T, Salgado-Lugo H, Galindo E, Peña C, Büchs J. Yeast extracts from different manufacturers and supplementation of amino acids and micro elements reveal a remarkable impact on alginate production by A. vinelandii ATCC9046. Microb Cell Fact 2023; 22:99. [PMID: 37170263 PMCID: PMC10176783 DOI: 10.1186/s12934-023-02112-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/03/2023] [Indexed: 05/13/2023] Open
Abstract
BACKGROUND In research and production, reproducibility is a key factor, to meet high quality and safety standards and maintain productivity. For microbial fermentations, complex substrates and media components are often used. The complex media components can vary in composition, depending on the lot and manufacturing process. These variations can have an immense impact on the results of biological cultivations. The aim of this work was to investigate and characterize the influence of the complex media component yeast extract on cultivations of Azotobacter vinelandii under microaerobic conditions. Under these conditions, the organism produces the biopolymer alginate. The focus of the investigation was on the respiration activity, cell growth and alginate production. RESULTS Yeast extracts from 6 different manufacturers and 2 different lots from one manufacturer were evaluated. Significant differences on respiratory activity, growth and production were observed. Concentration variations of three different yeast extracts showed that the performance of poorly performing yeast extracts can be improved by simply increasing their concentration. On the other hand, the results with well-performing yeast extracts seem to reach a saturation, when their concentration is increased. Cultivations with poorly performing yeast extract were supplemented with grouped amino acids, single amino acids and micro elements. Beneficial results were obtained with the supplementation of copper sulphate, cysteine or a combination of both. Furthermore, a correlation between the accumulated oxygen transfer and the final viscosity (as a key performance indicator), was established. CONCLUSION The choice of yeast extract is crucial for A. vinelandii cultivations, to maintain reproducibility and comparability between cultivations. The proper use of specific yeast extracts allows the cultivation results to be specifically optimised. In addition, supplements can be applied to modify and improve the properties of the alginate. The results only scratch the surface of the underlying mechanisms, as they are not providing explanations on a molecular level. However, the findings show the potential of optimising media containing yeast extract for alginate production with A. vinelandii, as well as the potential of targeted supplementation of the media.
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Affiliation(s)
- Sarah Sparviero
- Aachener Verfahrenstechnik - Chair of Biochemical Engineering, RWTH Aachen University, Bldg. NGP², Forckenbeckstr. 51, 52074, Aachen, Germany
| | - Max Daniel Dicke
- Aachener Verfahrenstechnik - Chair of Biochemical Engineering, RWTH Aachen University, Bldg. NGP², Forckenbeckstr. 51, 52074, Aachen, Germany
| | - Tobias M Rosch
- Aachener Verfahrenstechnik - Chair of Biochemical Engineering, RWTH Aachen University, Bldg. NGP², Forckenbeckstr. 51, 52074, Aachen, Germany
| | - Tania Castillo
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Universidad Nacional Autónoma de México, Ave. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Morelos, México
| | - Holjes Salgado-Lugo
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Universidad Nacional Autónoma de México, Ave. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Morelos, México
- Programa Investigadoras e Investigadores por México del CONACyT, Consejo Nacional de Ciencia y Tecnología, 03940, Mexico City, México
| | - Enrique Galindo
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Universidad Nacional Autónoma de México, Ave. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Morelos, México
| | - Carlos Peña
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Universidad Nacional Autónoma de México, Ave. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Morelos, México
| | - Jochen Büchs
- Aachener Verfahrenstechnik - Chair of Biochemical Engineering, RWTH Aachen University, Bldg. NGP², Forckenbeckstr. 51, 52074, Aachen, Germany.
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2
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The production and application of bacterial exopolysaccharides as biomaterials for bone regeneration. Carbohydr Polym 2022; 291:119550. [DOI: 10.1016/j.carbpol.2022.119550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 04/19/2022] [Accepted: 04/26/2022] [Indexed: 11/18/2022]
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Chuacharoen T, Aroonsong S, Chysirichote T. Alginate Production of Azotobacter vinelandii Using Sugar Cane Juice as the Main Carbon Source in an Airlift Bioreactor. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.2c02693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thanida Chuacharoen
- Faculty of Science and Technology, Suan Sunandha Rajabhat University, 1 U Thong Nok Rd, Dusit, Bangkok 10300, Thailand
| | - Soysruang Aroonsong
- Department of Food Engineering, School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, 1 Chalongkrung 1, Chalongkrung Rd, Ladkrabang, Bangkok 10520 Thailand
| | - Teerin Chysirichote
- Department of Food Engineering, School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, 1 Chalongkrung 1, Chalongkrung Rd, Ladkrabang, Bangkok 10520 Thailand
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López-Pliego L, González-Acocal V, García-González DL, Reyes-Nicolau JI, Sánchez-Cuapio Z, Meneses-Carbajal AS, Fuentes-Ramírez LE, Castañeda M. HrgS (Avin 34990), a novel histidine-kinase related to GacS, regulates alginate synthesis in Azotobacter vinelandii. FEMS Microbiol Lett 2022; 369:6546211. [PMID: 35266527 DOI: 10.1093/femsle/fnac024] [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: 08/15/2021] [Revised: 01/31/2022] [Accepted: 03/08/2022] [Indexed: 11/14/2022] Open
Abstract
Azotobacter vinelandii is a soil bacterium that produces alginates, a family of polymers of biotechnological interest. In A. vinelandii, alginate production is controlled by the two-component system GacS/GacA. GacS/GacA, in turn, regulates the Rsm post-transcriptional regulatory system establishing a cascade that regulates alginate biosynthesis by controlling the expression of the algD biosynthetic gene. In Pseudomonas aeruginosa, GacS/GacA is influenced by other histidine-kinases constituting a multicomponent signal transduction system. In this study, we explore the presence of GacS-related histidine-kinases in A. vinelandii and discover a novel histidine-kinase (Avin_34990, renamed HrgS). This histidin-kinase acts as a negative regulator of alginate synthesis by controlling the transcription of the sRNAs belonging to the Rsm post-transcriptional regulatory system, for which a functional GacS is required.
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Affiliation(s)
- Liliana López-Pliego
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla. IC-11 Ciudad Universitaria Puebla, Pue., C.P. 72000, México
| | - Verónica González-Acocal
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla. IC-11 Ciudad Universitaria Puebla, Pue., C.P. 72000, México
| | - Diana Laura García-González
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla. IC-11 Ciudad Universitaria Puebla, Pue., C.P. 72000, México
| | - Jimena Itzel Reyes-Nicolau
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla. IC-11 Ciudad Universitaria Puebla, Pue., C.P. 72000, México
| | - Zaira Sánchez-Cuapio
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla. IC-11 Ciudad Universitaria Puebla, Pue., C.P. 72000, México
| | - Alan Shared Meneses-Carbajal
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla. IC-11 Ciudad Universitaria Puebla, Pue., C.P. 72000, México
| | - Luis Ernesto Fuentes-Ramírez
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla. IC-11 Ciudad Universitaria Puebla, Pue., C.P. 72000, México
| | - Miguel Castañeda
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla. IC-11 Ciudad Universitaria Puebla, Pue., C.P. 72000, México
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5
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Takimoto R, Tatemichi Y, Aoki W, Kosaka Y, Minakuchi H, Ueda M, Kuroda K. A critical role of an oxygen-responsive gene for aerobic nitrogenase activity in Azotobacter vinelandii and its application to Escherichia coli. Sci Rep 2022; 12:4182. [PMID: 35264690 PMCID: PMC8907163 DOI: 10.1038/s41598-022-08007-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 02/28/2022] [Indexed: 12/02/2022] Open
Abstract
Since nitrogenase is irreversibly inactivated within a few minutes after exposure to oxygen, current studies on the heterologous expression of nitrogenase are limited to anaerobic conditions. This study comprehensively identified genes showing oxygen-concentration-dependent expression only under nitrogen-fixing conditions in Azotobacter vinelandii, an aerobic diazotroph. Among the identified genes, nafU, with an unknown function, was greatly upregulated under aerobic nitrogen-fixing conditions. Through replacement and overexpressing experiments, we suggested that nafU is involved in the maintenance of nitrogenase activity under aerobic nitrogenase activity. Furthermore, heterologous expression of nafU in nitrogenase-producing Escherichia coli increased nitrogenase activity under aerobic conditions by 9.7 times. Further analysis of NafU protein strongly suggested its localization in the inner membrane and raised the possibility that this protein may lower the oxygen concentration inside the cells. These findings provide new insights into the mechanisms for maintaining stable nitrogenase activity under aerobic conditions in A. vinelandii and provide a platform to advance the use of nitrogenase under aerobic conditions.
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Affiliation(s)
- Ren Takimoto
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Yuki Tatemichi
- Research and Development Division, Kikkoman Corporation, 338 Noda, Noda, Chiba, 278-0037, Japan
| | - Wataru Aoki
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Yuishin Kosaka
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | | | - Mitsuyoshi Ueda
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Kouichi Kuroda
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.
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6
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Monteagudo-Cascales E, Santero E, Canosa I. The Regulatory Hierarchy Following Signal Integration by the CbrAB Two-Component System: Diversity of Responses and Functions. Genes (Basel) 2022; 13:genes13020375. [PMID: 35205417 PMCID: PMC8871633 DOI: 10.3390/genes13020375] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/14/2022] [Accepted: 02/16/2022] [Indexed: 02/04/2023] Open
Abstract
CbrAB is a two-component system, unique to bacteria of the family Pseudomonaceae, capable of integrating signals and involved in a multitude of physiological processes that allow bacterial adaptation to a wide variety of varying environmental conditions. This regulatory system provides a great metabolic versatility that results in excellent adaptability and metabolic optimization. The two-component system (TCS) CbrA-CbrB is on top of a hierarchical regulatory cascade and interacts with other regulatory systems at different levels, resulting in a robust output. Among the regulatory systems found at the same or lower levels of CbrAB are the NtrBC nitrogen availability adaptation system, the Crc/Hfq carbon catabolite repression cascade in Pseudomonas, or interactions with the GacSA TCS or alternative sigma ECF factor, such as SigX. The interplay between regulatory mechanisms controls a number of physiological processes that intervene in important aspects of bacterial adaptation and survival. These include the hierarchy in the use of carbon sources, virulence or resistance to antibiotics, stress response or definition of the bacterial lifestyle. The multiple actions of the CbrAB TCS result in an important competitive advantage.
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Affiliation(s)
| | - Eduardo Santero
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Centro Andaluz de Biología del Desarrollo, CSIC, Junta de Andalucía, 41013 Seville, Spain;
| | - Inés Canosa
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Centro Andaluz de Biología del Desarrollo, CSIC, Junta de Andalucía, 41013 Seville, Spain;
- Correspondence: ; Tel.: +34-954349052
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7
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Dudun AA, Akoulina EA, Zhuikov VA, Makhina TK, Voinova VV, Belishev NV, Khaydapova DD, Shaitan KV, Bonartseva GA, Bonartsev AP. Competitive Biosynthesis of Bacterial Alginate Using Azotobacter vinelandii 12 for Tissue Engineering Applications. Polymers (Basel) 2021; 14:polym14010131. [PMID: 35012152 PMCID: PMC8747204 DOI: 10.3390/polym14010131] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/17/2021] [Accepted: 12/23/2021] [Indexed: 11/16/2022] Open
Abstract
This study investigated the effect of various cultivation conditions (sucrose/phosphate concentrations, aeration level) on alginate biosynthesis using the bacterial producing strain Azotobacter vinelandii 12 by the full factorial design (FFD) method and physicochemical properties (e.g., rheological properties) of the produced bacterial alginate. We demonstrated experimentally the applicability of bacterial alginate for tissue engineering (the cytotoxicity testing using mesenchymal stem cells (MSCs)). The isolated synthesis of high molecular weight (Mw) capsular alginate with a high level of acetylation (25%) was achieved by FFD method under a low sucrose concentration, an increased phosphate concentration, and a high aeration level. Testing the viscoelastic properties and cytotoxicity showed that bacterial alginate with a maximal Mw (574 kDa) formed the densest hydrogels (which demonstrated relatively low cytotoxicity for MSCs in contrast to bacterial alginate with low Mw). The obtained data have shown promising prospects in controlled biosynthesis of bacterial alginate with different physicochemical characteristics for various biomedical applications including tissue engineering.
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Affiliation(s)
- Andrei A. Dudun
- Research Center of Biotechnology of the Russian Academy of Sciences Leninsky Ave, 33, Bld. 2, 119071 Moscow, Russia; (A.A.D.); (V.A.Z.); (T.K.M.); (G.A.B.)
| | - Elizaveta A. Akoulina
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1-12, 119234 Moscow, Russia; (E.A.A.); (V.V.V.); (N.V.B.); (K.V.S.)
| | - Vsevolod A. Zhuikov
- Research Center of Biotechnology of the Russian Academy of Sciences Leninsky Ave, 33, Bld. 2, 119071 Moscow, Russia; (A.A.D.); (V.A.Z.); (T.K.M.); (G.A.B.)
| | - Tatiana K. Makhina
- Research Center of Biotechnology of the Russian Academy of Sciences Leninsky Ave, 33, Bld. 2, 119071 Moscow, Russia; (A.A.D.); (V.A.Z.); (T.K.M.); (G.A.B.)
| | - Vera V. Voinova
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1-12, 119234 Moscow, Russia; (E.A.A.); (V.V.V.); (N.V.B.); (K.V.S.)
| | - Nikita V. Belishev
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1-12, 119234 Moscow, Russia; (E.A.A.); (V.V.V.); (N.V.B.); (K.V.S.)
| | - Dolgor D. Khaydapova
- Department of Soil Physics and Reclamation, Soil Science Faculty, M.V. Lomonosov Moscow State University, Leninskie Gory 1-12, 119234 Moscow, Russia;
| | - Konstantin V. Shaitan
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1-12, 119234 Moscow, Russia; (E.A.A.); (V.V.V.); (N.V.B.); (K.V.S.)
| | - Garina A. Bonartseva
- Research Center of Biotechnology of the Russian Academy of Sciences Leninsky Ave, 33, Bld. 2, 119071 Moscow, Russia; (A.A.D.); (V.A.Z.); (T.K.M.); (G.A.B.)
| | - Anton P. Bonartsev
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1-12, 119234 Moscow, Russia; (E.A.A.); (V.V.V.); (N.V.B.); (K.V.S.)
- Correspondence: ; Tel.: +7-4959306306
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Carruthers BM, Garcia AK, Rivier A, Kacar B. Automated Laboratory Growth Assessment and Maintenance of Azotobacter vinelandii. Curr Protoc 2021; 1:e57. [PMID: 33656286 DOI: 10.1002/cpz1.57] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Azotobacter vinelandii (A. vinelandii) is a commonly used model organism for the study of aerobic respiration, the bacterial production of several industrially relevant compounds, and, perhaps most significantly, the genetics and biochemistry of biological nitrogen fixation. Laboratory growth assessments of A. vinelandii are useful for evaluating the impact of environmental and genetic modifications on physiological properties, including diazotrophy. However, researchers typically rely on manual growth methods that are oftentimes laborious and inefficient. We present a protocol for the automated growth assessment of A. vinelandii on a microplate reader, particularly well-suited for studies of diazotrophic growth. We discuss common pitfalls and strategies for protocol optimization, and demonstrate the protocol's application toward growth evaluation of strains carrying modifications to nitrogen-fixation genes. © 2021 The Authors. Basic Protocol 1: Preparation of A. vinelandii plate cultures from frozen stock Basic Protocol 2: Preparation of A. vinelandii liquid precultures Basic Protocol 3: Automated growth rate experiment of A. vinelandii on a microplate reader.
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Affiliation(s)
- Brooke M Carruthers
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona
| | - Amanda K Garcia
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona
| | - Alex Rivier
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona
| | - Betul Kacar
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona.,Department of Astronomy and Steward Observatory, University of Arizona, Tucson, Arizona.,Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona
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Aasfar A, Bargaz A, Yaakoubi K, Hilali A, Bennis I, Zeroual Y, Meftah Kadmiri I. Nitrogen Fixing Azotobacter Species as Potential Soil Biological Enhancers for Crop Nutrition and Yield Stability. Front Microbiol 2021; 12:628379. [PMID: 33717018 PMCID: PMC7947814 DOI: 10.3389/fmicb.2021.628379] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 02/05/2021] [Indexed: 12/20/2022] Open
Abstract
Biological nitrogen fixation (BNF) refers to a microbial mediated process based upon an enzymatic "Nitrogenase" conversion of atmospheric nitrogen (N2) into ammonium readily absorbable by roots. N2-fixing microorganisms collectively termed as "diazotrophs" are able to fix biologically N2 in association with plant roots. Specifically, the symbiotic rhizobacteria induce structural and physiological modifications of bacterial cells and plant roots into specialized structures called nodules. Other N2-fixing bacteria are free-living fixers that are highly diverse and globally widespread in cropland. They represent key natural source of nitrogen (N) in natural and agricultural ecosystems lacking symbiotic N fixation (SNF). In this review, the importance of Azotobacter species was highlighted as both important free-living N2-fixing bacteria and potential bacterial biofertilizer with proven efficacy for plant nutrition and biological soil fertility. In addition, we described Azotobacter beneficial plant promoting traits (e.g., nutrient use efficiency, protection against phytopathogens, phytohormone biosynthesis, etc.). We shed light also on the agronomic features of Azotobacter that are likely an effective component of integrated plant nutrition strategy, which contributes positively to sustainable agricultural production. We pointed out Azotobacter based-biofertilizers, which possess unique characteristics such as cyst formation conferring resistance to environmental stresses. Such beneficial traits can be explored profoundly for the utmost aim to research and develop specific formulations based on inoculant Azotobacter cysts. Furthermore, Azotobacter species still need to be wisely exploited in order to address specific agricultural challenges (e.g., nutrient deficiencies, biotic and abiotic constraints) taking into consideration several variables including their biological functions, synergies and multi-trophic interactions, and biogeography and abundance distribution.
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Affiliation(s)
- Abderrahim Aasfar
- Green Biotechnology Laboratory, Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), Rabat Design Centre, Rabat, Morocco.,Laboratory of Health Sciences and Technologies, High Institute of Health Sciences, Hassan 1st University, Settat, Morocco
| | - Adnane Bargaz
- AgroBioSciences-Microbiome, Laboratory of Plant-Microbe Interactions, Mohammed VI Polytechnic University, Ben Guerir, Morocco
| | - Kaoutar Yaakoubi
- Green Biotechnology Laboratory, Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), Rabat Design Centre, Rabat, Morocco
| | - Abderraouf Hilali
- Laboratory of Health Sciences and Technologies, High Institute of Health Sciences, Hassan 1st University, Settat, Morocco
| | - Iman Bennis
- Green Biotechnology Laboratory, Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), Rabat Design Centre, Rabat, Morocco
| | | | - Issam Meftah Kadmiri
- Green Biotechnology Laboratory, Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), Rabat Design Centre, Rabat, Morocco.,AgroBioSciences-Microbiome, Laboratory of Plant-Microbe Interactions, Mohammed VI Polytechnic University, Ben Guerir, Morocco
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10
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Sun X, Zhang J. Bacterial exopolysaccharides: Chemical structures, gene clusters and genetic engineering. Int J Biol Macromol 2021; 173:481-490. [PMID: 33493567 DOI: 10.1016/j.ijbiomac.2021.01.139] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 11/25/2022]
Abstract
In recent decades, the composition, structure, biosynthesis, and function of bacterial extracellular polysaccharides (EPS) have been extensively studied. EPS are synthesized through different biosynthetic pathways. The genes responsible for EPS synthesis are usually clustered on the genome or large plasmids of bacteria. Generally, different EPS synthesis gene clusters direct the synthesis of EPS with different chemical structures and biological activities. A better understanding of the gene functions involved in EPS biosynthesis is critical for the production of EPS with special biological activities. Genetic engineering methods are usually used to study EPS synthesis related genes. This review organizes the available information on EPS, including their structures, synthesis of related genes, and highlights the research progress of modifying EPS gene clusters through gene-editing methods.
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Affiliation(s)
- Xiaqing Sun
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China
| | - Jianfa Zhang
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China.
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11
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Increased c-di-GMP Levels Lead to the Production of Alginates of High Molecular Mass in Azotobacter vinelandii. J Bacteriol 2020; 202:JB.00134-20. [PMID: 32989088 DOI: 10.1128/jb.00134-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022] Open
Abstract
Azotobacter vinelandii produces the linear exopolysaccharide alginate, a compound of significant biotechnological importance. The biosynthesis of alginate in A. vinelandii and Pseudomonas aeruginosa has several similarities but is regulated somewhat differently in the two microbes. Here, we show that the second messenger cyclic dimeric GMP (c-di-GMP) regulates the production and the molecular mass of alginate in A. vinelandii The hybrid protein MucG, containing conserved GGDEF and EAL domains and N-terminal HAMP and PAS domains, behaved as a c-di-GMP phosphodiesterase (PDE). This activity was found to negatively affect the amount and molecular mass of the polysaccharide formed. On the other hand, among the diguanylate cyclases (DGCs) present in A. vinelandii, AvGReg, a globin-coupled sensor (GCS) DGC that directly binds to oxygen, was identified as the main c-di-GMP-synthesizing contributor to alginate production. Overproduction of AvGReg in the parental strain phenocopied a ΔmucG strain with regard to alginate production and the molecular mass of the polymer. MucG was previously shown to prevent the synthesis of high-molecular-mass alginates in response to reduced oxygen transfer rates (OTRs). In this work, we show that cultures exposed to reduced OTRs accumulated higher levels of c-di-GMP; this finding strongly suggests that at least one of the molecular mechanisms involved in modulation of alginate production and molecular mass by oxygen depends on a c-di-GMP signaling module that includes the PAS domain-containing PDE MucG and the GCS DGC AvGReg.IMPORTANCE c-di-GMP has been widely recognized for its essential role in the production of exopolysaccharides in bacteria, such as alginate produced by Pseudomonas and Azotobacter spp. This study reveals that the levels of c-di-GMP also affect the physical properties of alginate, favoring the production of high-molecular-mass alginates in response to lower OTRs. This finding opens up new alternatives for the design of tailor-made alginates for biotechnological applications.
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Fan X, Zhang Y, Zhao F, Liu Y, Zhao Y, Wang S, Liu R, Yang C. Genome reduction enhances production of polyhydroxyalkanoate and alginate oligosaccharide in Pseudomonas mendocina. Int J Biol Macromol 2020; 163:2023-2031. [DOI: 10.1016/j.ijbiomac.2020.09.067] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/11/2020] [Accepted: 09/10/2020] [Indexed: 12/15/2022]
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13
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Respiration in Azotobacter vinelandii and its relationship with the synthesis of biopolymers. ELECTRON J BIOTECHN 2020. [DOI: 10.1016/j.ejbt.2020.08.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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14
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Gene expression abundance dictated exopolysaccharide modification in Rhizobium radiobacter SZ4S7S14 as the cell's response to salt stress. Int J Biol Macromol 2020; 164:4339-4347. [PMID: 32931833 DOI: 10.1016/j.ijbiomac.2020.09.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/25/2020] [Accepted: 09/07/2020] [Indexed: 12/24/2022]
Abstract
A molecular and metabolic behaviour of EPS-producing and salt-tolerant bacterium Rhizobium radiobacter SZ4S7S14 along with its practical application in salt-stress was investigated. The research target was identification and expression profiles of a large EPS biosynthesis gene cluster, possible structural modification of EPS under salt-stress effect and analysis of the gene(s) relative expression and structural modification correlation. As expected, transposons insertions were identified within or near the coding regions of exoK and exoM, previously known large gene cluster that is required for EPS I synthesis. Different expression levels of exoK and exoM in different salt-stress models resulted in structural modification of EPS, which was seen basically in monomers molar ratio. As a result of downregulation of the genes the strain produced EPS samples with monomers ratio: (1) Glu:Man:Gal:Xyl:Ara:Rha:Rib = 31.21:3.02:2.77:1:0.91:0.64:0.41 (in 0.25% NaCl); (2) Glu:Man:Gal:Xyl:Ara:Rha:Rib = 7.65:1:0.69:0.22:0.2:0.16:0.1 (in 0.5% NaCl); (3) Glu:Man:Gal:Ara:Xyl:Rha:Rib = 9.39:1.89:1:0.58:0.52:0.46:0.26 (in 1% NaCl); and (4) Glu:Man:Ara:Xyl:Rib:Gal = 7.9:2:2:1.58:1.1:1 (in 2.0% NaCl), whereas in control (without NaCl): Glc:Man:Gal:Xyl:Ara:Rha:Rib = 11.66:1:0.90:0.37:0.37:0.15:0.14. It was found that, salt-stress not only leads to downregulation of a large EPS biosynthesis gene cluster, including exoK and exoM genes, but also impacting on their relative expression degree, re-groups of the monomers within the EPS matrix and dictates molar ratio of the monosaccharides in the final metabolite.
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15
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Gómez-Hernández E, Salgado-Lugo H, Segura D, García A, Díaz-Barrera A, Peña C. Production of Poly-3-Hydroxybutyrate (P3HB) with Ultra-High Molecular Weight (UHMW) by Mutant Strains of Azotobacter vinelandii Under Microaerophilic Conditions. Appl Biochem Biotechnol 2020; 193:79-95. [PMID: 32813183 DOI: 10.1007/s12010-020-03384-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 06/22/2020] [Indexed: 11/28/2022]
Abstract
Poly-3-hydroxybutyrate (P3HB) is a biopolymer, which presents characteristics similar to those of plastics derived from the petrochemical industry. The thermomechanical properties and biodegradability of P3HB are influenced by its molecular weight (MW). The aim of the present study was to evaluate the changes of the molecular weight of P3HB as a function of oxygen transfer rate (OTR) in the cultures using two strains of Azotobacter vinelandii, a wild-type strain OP, and PhbZ1 mutant with a P3HB depolymerase inactivated. Both strains were grown in a bioreactor under different OTR conditions. An inverse relationship was found between the average molecular weight of P3HB and the OTRmax, obtaining a polymer with a maximal MW (8000-10,000 kDa) from the cultures developed at OTRmax of 5 mmol L-1 h-1 using both strains, with respect to the cultures conducted at 8 and 11 mmol L-1 h-1, which produced a P3HB between 4000 and 5000 kDa. The increase in MW of P3HB was related to the activity of enzymes involved in the synthesis and depolymerization. Overall, our results show that it is possible to modulate the average molecular weight of P3HB by manipulating oxygen transfer conditions with both strains (OP and PhbZ1 mutant) of A. vinelandii.
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Affiliation(s)
- Elsa Gómez-Hernández
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Mor, Mexico
| | - Holjes Salgado-Lugo
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Mor, Mexico
| | - Daniel Segura
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Mor, Mexico
| | - Andrés García
- Laboratorio de Biotecnología Ambiental, Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico
| | - Alvaro Díaz-Barrera
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2147 Casilla, 4059, Valparaíso, Chile
| | - Carlos Peña
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Mor, Mexico.
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16
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Campos DT, Zuñiga C, Passi A, Del Toro J, Tibocha-Bonilla JD, Zepeda A, Betenbaugh MJ, Zengler K. Modeling of nitrogen fixation and polymer production in the heterotrophic diazotroph Azotobacter vinelandii DJ. Metab Eng Commun 2020; 11:e00132. [PMID: 32551229 PMCID: PMC7292883 DOI: 10.1016/j.mec.2020.e00132] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 05/09/2020] [Accepted: 05/11/2020] [Indexed: 01/28/2023] Open
Abstract
Nitrogen fixation is an important metabolic process carried out by microorganisms, which converts molecular nitrogen into inorganic nitrogenous compounds such as ammonia (NH3). These nitrogenous compounds are crucial for biogeochemical cycles and for the synthesis of essential biomolecules, i.e. nucleic acids, amino acids and proteins. Azotobacter vinelandii is a bacterial non-photosynthetic model organism to study aerobic nitrogen fixation (diazotrophy) and hydrogen production. Moreover, the diazotroph can produce biopolymers like alginate and polyhydroxybutyrate (PHB) that have important industrial applications. However, many metabolic processes such as partitioning of carbon and nitrogen metabolism in A. vinelandii remain unknown to date. Genome-scale metabolic models (M-models) represent reliable tools to unravel and optimize metabolic functions at genome-scale. M-models are mathematical representations that contain information about genes, reactions, metabolites and their associations. M-models can simulate optimal reaction fluxes under a wide variety of conditions using experimentally determined constraints. Here we report on the development of a M-model of the wild type bacterium A. vinelandii DJ (iDT1278) which consists of 2,003 metabolites, 2,469 reactions, and 1,278 genes. We validated the model using high-throughput phenotypic and physiological data, testing 180 carbon sources and 95 nitrogen sources. iDT1278 was able to achieve an accuracy of 89% and 91% for growth with carbon sources and nitrogen source, respectively. This comprehensive M-model will help to comprehend metabolic processes associated with nitrogen fixation, ammonium assimilation, and production of organic nitrogen in an environmentally important microorganism. Genome-scale metabolic model of Azotobacter vinelandii DJ achives over 90% accuracy. iDT1278 is the most comprehensive model to simulate diazotrophy. Determining the most suitable culture conditions to produce polymers A. vinelandii. Constraint-based modeling unravels links among nitrogen fixation and production of organic nitrogen.
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Affiliation(s)
- Diego Tec Campos
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA.,Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| | - Cristal Zuñiga
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA
| | - Anurag Passi
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA
| | - John Del Toro
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA
| | - Juan D Tibocha-Bonilla
- Bioinformatics and Systems Biology Graduate Program, University of California, San Diego, La Jolla, CA, 92093-0412, USA
| | - Alejandro Zepeda
- Facultad de Ingeniería Química, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| | - Michael J Betenbaugh
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA
| | - Karsten Zengler
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0760, USA.,Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093-0412, USA.,Center for Microbiome Innovation, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0403, USA
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17
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Dudun AA, Akoulina EA, Voinova VV, Makhina TK, Myshkina VL, Zhuikov VA, Bonartsev AP, Bonartseva GA. Biosynthesis of Alginate and Poly(3-Hydroxybutyrate) by the Bacterial Strain Azotobacter agile 12. APPL BIOCHEM MICRO+ 2019. [DOI: 10.1134/s0003683819060073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Study of the sRNA RsmY involved in the genetic regulation of the synthesis of alginate and alkyl resorcinols in Azotobacter vinelandii. Arch Microbiol 2019; 202:579-589. [DOI: 10.1007/s00203-019-01769-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 11/01/2019] [Accepted: 11/07/2019] [Indexed: 12/21/2022]
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19
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Liu J, Yang S, Li X, Yan Q, Reaney MJT, Jiang Z. Alginate Oligosaccharides: Production, Biological Activities, and Potential Applications. Compr Rev Food Sci Food Saf 2019; 18:1859-1881. [DOI: 10.1111/1541-4337.12494] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/09/2019] [Accepted: 07/29/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Jun Liu
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthCollege of Food Science and Nutritional EngineeringChina Agricultural Univ. Beijing 100083 China
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Technology and Business Univ. Beijing 100048 China
| | - Shaoqing Yang
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthCollege of Food Science and Nutritional EngineeringChina Agricultural Univ. Beijing 100083 China
| | - Xiuting Li
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthBeijing Technology and Business Univ. Beijing 100048 China
| | - Qiaojuan Yan
- Bioresource Utilization LaboratoryCollege of EngineeringChina Agricultural Univ. Beijing 100083 China
| | - Martin J. T. Reaney
- Dept. of Plant SciencesUniv. of Saskatchewan Saskatoon SK S7N 5A8 Canada
- Guangdong Saskatchewan Oilseed Joint Laboratory (GUSTO)Dept. of Food Science and EngineeringJinan Univ. Guangzhou 510632 China
| | - Zhengqiang Jiang
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthCollege of Food Science and Nutritional EngineeringChina Agricultural Univ. Beijing 100083 China
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20
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Nehal F, Sahnoun M, Smaoui S, Jaouadi B, Bejar S, Mohammed S. Characterization, high production and antimicrobial activity of exopolysaccharides from Lactococcus lactis F-mou. Microb Pathog 2019; 132:10-19. [DOI: 10.1016/j.micpath.2019.04.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 04/09/2019] [Accepted: 04/10/2019] [Indexed: 12/01/2022]
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21
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Use of Anionic Polysaccharides in the Development of 3D Bioprinting Technology. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9132596] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Three-dimensional (3D) bioprinting technology is now one of the best ways to generate new biomaterial for potential biomedical applications. Significant progress in this field since two decades ago has pointed the way toward use of natural biopolymers such as polysaccharides. Generally, these biopolymers such as alginate possess specific reactive groups such as carboxylate able to be chemically or enzymatically functionalized to generate very interesting hydrogel structures with biomedical applications in cell generation. This present review gives an overview of the main natural anionic polysaccharides and focuses on the description of the 3D bioprinting concept with the recent development of bioprinting processes using alginate as polysaccharide.
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22
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Wu H, Chen S, Ji M, Chen Q, Shi J, Sun J. Activation of colanic acid biosynthesis linked to heterologous expression of the polyhydroxybutyrate pathway in Escherichia coli. Int J Biol Macromol 2019; 128:752-760. [DOI: 10.1016/j.ijbiomac.2019.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/01/2019] [Accepted: 02/02/2019] [Indexed: 01/31/2023]
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23
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Aarstad OA, Stanisci A, Sætrom GI, Tøndervik A, Sletta H, Aachmann FL, Skjåk-Bræk G. Biosynthesis and Function of Long Guluronic Acid-Blocks in Alginate Produced by Azotobacter vinelandii. Biomacromolecules 2019; 20:1613-1622. [DOI: 10.1021/acs.biomac.8b01796] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Olav Andreas Aarstad
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, NTNU, Sem Sælands vei 6-8, N-7491 Trondheim, Norway
| | - Annalucia Stanisci
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, NTNU, Sem Sælands vei 6-8, N-7491 Trondheim, Norway
| | - Gerd Inger Sætrom
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, NTNU, Sem Sælands vei 6-8, N-7491 Trondheim, Norway
| | - Anne Tøndervik
- SINTEF Industry, Department of Biotechnology and Nanomedicine, Richard Birkelands vei 3B, 7034 Trondheim, Norway
| | - Håvard Sletta
- SINTEF Industry, Department of Biotechnology and Nanomedicine, Richard Birkelands vei 3B, 7034 Trondheim, Norway
| | - Finn Lillelund Aachmann
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, NTNU, Sem Sælands vei 6-8, N-7491 Trondheim, Norway
| | - Gudmund Skjåk-Bræk
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, NTNU, Sem Sælands vei 6-8, N-7491 Trondheim, Norway
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24
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Poly(3-hydroxybutyrate) accumulation by Azotobacter vinelandii under different oxygen transfer strategies. J Ind Microbiol Biotechnol 2019; 46:13-19. [PMID: 30357504 DOI: 10.1007/s10295-018-2090-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 10/16/2018] [Indexed: 10/28/2022]
Abstract
Azotobacter vinelandii OP is a bacterium that produces poly(3-hydroxybutyrate) (PHB). PHB production in a stirred bioreactor, at different oxygen transfer strategies, was evaluated. By applying different oxygen contents in the inlet gas, the oxygen transfer rate (OTR) was changed under a constant agitation rate. Batch cultures were performed without dissolved oxygen tension (DOT) control (using 9% and 21% oxygen in the inlet gas) and under DOT control (4%) using gas blending. The cultures that developed without DOT control were limited by oxygen. As result of varying the oxygen content in the inlet gas, a lower OTR (4.6 mmol L-1 h-1) and specific oxygen uptake rate (11.6 mmol g-1 h-1) were obtained using 9% oxygen in the inlet gas. The use of 9% oxygen in the inlet gas was the most suitable for improving the intracellular PHB content (56 ± 6 w w-1). For the first time, PHB accumulation in A. vinelandii OP cultures, developed with different OTRs, was compared under homogeneous mixing conditions, demonstrating that bacterial respiration affects PHB synthesis. These results can be used to design new oxygen transfer strategies to produce PHB under productive conditions.
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25
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Bedoya-Pérez LP, Muriel-Millán LF, Moreno S, Quiroz-Rocha E, Rivera-Gómez N, Espín G. The pyrophosphohydrolase RppH is involved in the control of RsmA/CsrA expression in Azotobacter vinelandii and Escherichia coli. Microbiol Res 2018; 214:91-100. [DOI: 10.1016/j.micres.2018.05.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 03/28/2018] [Accepted: 05/17/2018] [Indexed: 02/06/2023]
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26
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López-Pliego L, García-Ramírez L, Cruz-Gómez EA, Domínguez-Ojeda P, López-Pastrana A, Fuentes-Ramírez LE, Núñez C, Castañeda M. Transcriptional Study of the RsmZ-sRNAs and Their Relationship to the Biosynthesis of Alginate and Alkylresorcinols in Azotobacter vinelandii. Mol Biotechnol 2018; 60:670-680. [DOI: 10.1007/s12033-018-0102-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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27
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Kutralam-Muniasamy G, Peréz-Guevara F. Genome characteristics dictate poly-R-(3)-hydroxyalkanoate production in Cupriavidus necator H16. World J Microbiol Biotechnol 2018; 34:79. [DOI: 10.1007/s11274-018-2460-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/19/2018] [Indexed: 11/28/2022]
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28
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Dai X, Gao G, Wu M, Wei W, Qu J, Li G, Ma T. Construction and application of a Xanthomonas campestris CGMCC15155 strain that produces white xanthan gum. Microbiologyopen 2018; 8:e00631. [PMID: 29656507 PMCID: PMC6391268 DOI: 10.1002/mbo3.631] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 01/19/2018] [Accepted: 02/28/2018] [Indexed: 11/14/2022] Open
Abstract
In the industrial production of xanthan gum using Xanthomonas campestris CGMCC15155, large amounts of ethanol are required to extract xanthan gum from the fermentation broth and remove xanthomonadin impurities. To reduce the amount of ethanol and the overall production cost of xanthan gum, a xanthomonadin‐deficient strain of CGMCC15155 was constructed by inserting the Vitreoscilla globin (vgb) gene, under the control of the LacZ promoter, into the region of the pigA gene, which is involved in xanthomonadin synthesis. The insertion of vgb inactivated pigA, resulting in the production of white xanthan gum. The lack of xanthomonadins resulted in a decreased yield of xanthan gum. However, the expression product of vgb gene, VHb, could increase the metabolism of X. campestris, which allowed the production of xanthan gum to reach wild‐type levels in the engineered strain. The yield, molecular weight, and rheological properties of the xanthan gum synthesized by the engineered and wild‐type bacteria were essentially the same. When the same volume of ethanol was used, the whiteness values of the xanthan gum extracted from engineered and wild‐type bacteria were 65.20 and 38.17, respectively. To extract xanthan gum with the same whiteness, three and seven times the fermentation volume of ethanol was required for the engineered and wild‐type strains, respectively. Thus, the engineered train reduced the requirement for ethanol in xanthan gum production by 133.3%. The results demonstrated that the engineered bacteria used less ethanol, thus reducing the downstream processing cost in xanthan gum production.
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Affiliation(s)
- Xiaohui Dai
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Ge Gao
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Mengmeng Wu
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Weiying Wei
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Jianmei Qu
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Guoqiang Li
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China.,Tianjin Engineering Technology Center of Green Manufacturing Biobased Materials, Tianjin, China
| | - Ting Ma
- Key Laboratory of Molecular Microbiology Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China.,Tianjin Engineering Technology Center of Green Manufacturing Biobased Materials, Tianjin, China
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29
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Nouha K, Kumar RS, Balasubramanian S, Tyagi RD. Critical review of EPS production, synthesis and composition for sludge flocculation. J Environ Sci (China) 2018; 66:225-245. [PMID: 29628091 DOI: 10.1016/j.jes.2017.05.020] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 05/12/2017] [Accepted: 05/12/2017] [Indexed: 05/08/2023]
Abstract
Extracellular polymeric substances (EPS) produced by microorganisms represent biological macromolecules with unfathomable potentials and they are required to be explored further for their potential application as a bioflocculant in various wastewater sludge treatment. Although several studies already exist on biosynthetic pathways of different classical biopolymers like alginate and xanthan, no dedicated studies are available for EPS in sludge. This review highlights the EPS composition, functionality, and biodegradability for its potential use as a carbon source for production of other metabolites. Furthermore, the effect of various extraction methods (physical and chemical) on compositional, structural, physical and functional properties of microbial EPS has been addressed. The vital knowledge of the effect of extraction method on various important attributes of EPS can help to choose the suitable extraction method depending upon the intended use of EPS. The possible use of different molecular biological techniques for enhanced production of desired EPS was summarized.
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Affiliation(s)
- Klai Nouha
- Université du Québec, Institut national de la Recherche Scientifique, Centre Eau, Terre & Environnement, 490 de la Couronne, Québec G1K 9A9, Canada
| | - Ram Saurabh Kumar
- Université du Québec, Institut national de la Recherche Scientifique, Centre Eau, Terre & Environnement, 490 de la Couronne, Québec G1K 9A9, Canada.
| | | | - Rajeshwar Dayal Tyagi
- Université du Québec, Institut national de la Recherche Scientifique, Centre Eau, Terre & Environnement, 490 de la Couronne, Québec G1K 9A9, Canada
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30
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Noar JD, Bruno-Bárcena JM. Azotobacter vinelandii: the source of 100 years of discoveries and many more to come. MICROBIOLOGY-SGM 2018. [PMID: 29533747 DOI: 10.1099/mic.0.000643] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Azotobacter vinelandii has been studied for over 100 years since its discovery as an aerobic nitrogen-fixing organism. This species has proved useful for the study of many different biological systems, including enzyme kinetics and the genetic code. It has been especially useful in working out the structures and mechanisms of different nitrogenase enzymes, how they can function in oxic environments and the interactions of nitrogen fixation with other aspects of metabolism. Interest in studying A. vinelandii has waned in recent decades, but this bacterium still possesses great potential for new discoveries in many fields and commercial applications. The species is of interest for research because of its genetic pliability and natural competence. Its features of particular interest to industry are its ability to produce multiple valuable polymers - bioplastic and alginate in particular; its nitrogen-fixing prowess, which could reduce the need for synthetic fertilizer in agriculture and industrial fermentations, via coculture; its production of potentially useful enzymes and metabolic pathways; and even its biofuel production abilities. This review summarizes the history and potential for future research using this versatile microbe.
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Affiliation(s)
- Jesse D Noar
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
| | - Jose M Bruno-Bárcena
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
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31
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García A, Ferrer P, Albiol J, Castillo T, Segura D, Peña C. Metabolic flux analysis and the NAD(P)H/NAD(P) + ratios in chemostat cultures of Azotobacter vinelandii. Microb Cell Fact 2018; 17:10. [PMID: 29357933 PMCID: PMC5776761 DOI: 10.1186/s12934-018-0860-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 01/15/2018] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Azotobacter vinelandii is a bacterium that produces alginate and polyhydroxybutyrate (P3HB); however, the role of NAD(P)H/NAD(P)+ ratios on the metabolic fluxes through biosynthesis pathways of these biopolymers remains unknown. The aim of this study was to evaluate the NAD(P)H/NAD(P) + ratios and the metabolic fluxes involved in alginate and P3HB biosynthesis, under oxygen-limiting and non-limiting oxygen conditions. RESULTS The results reveal that changes in the oxygen availability have an important effect on the metabolic fluxes and intracellular NADPH/NADP+ ratio, showing that at the lowest OTR (2.4 mmol L-1 h-1), the flux through the tricarboxylic acid (TCA) cycle decreased 27.6-fold, but the flux through the P3HB biosynthesis increased 6.6-fold in contrast to the cultures without oxygen limitation (OTR = 14.6 mmol L-1 h-1). This was consistent with the increase in the level of transcription of phbB and the P3HB biosynthesis. In addition, under conditions without oxygen limitation, there was an increase in the carbon uptake rate (twofold), as well as in the flux through the pentose phosphate (PP) pathway (4.8-fold), compared to the condition of 2.4 mmol L-1 h-1. At the highest OTR condition, a decrease in the NADPH/NADP+ ratio of threefold was observed, probably as a response to the high respiration rate induced by the respiratory protection of the nitrogenase under diazotrophic conditions, correlating with a high expression of the uncoupled respiratory chain genes (ndhII and cydA) and induction of the expression of the genes encoding the nitrogenase complex (nifH). CONCLUSIONS We have demonstrated that changes in oxygen availability affect the internal redox state of the cell and carbon metabolic fluxes. This also has a strong impact on the TCA cycle and PP pathway as well as on alginate and P3HB biosynthetic fluxes.
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Affiliation(s)
- Andres García
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa Cuernavaca, Apdo. Post. 510-3, 62210, Cuernavaca, Morelos, Mexico
| | - Pau Ferrer
- Departament d'Engiyeria Química, Biològica i Ambiental, Escola d'Enginyeria, Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallés), Barcelona, Spain
| | - Joan Albiol
- Departament d'Engiyeria Química, Biològica i Ambiental, Escola d'Enginyeria, Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallés), Barcelona, Spain
| | - Tania Castillo
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa Cuernavaca, Apdo. Post. 510-3, 62210, Cuernavaca, Morelos, Mexico
| | - Daniel Segura
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa Cuernavaca, 62210, Cuernavaca, Morelos, Mexico
| | - Carlos Peña
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa Cuernavaca, Apdo. Post. 510-3, 62210, Cuernavaca, Morelos, Mexico.
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Freitas F, Torres CAV, Reis MAM. Engineering aspects of microbial exopolysaccharide production. BIORESOURCE TECHNOLOGY 2017; 245:1674-1683. [PMID: 28554522 DOI: 10.1016/j.biortech.2017.05.092] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 05/13/2017] [Accepted: 05/15/2017] [Indexed: 06/07/2023]
Abstract
Although the ability to secrete exopolysaccharides (EPS) is widespread among microorganisms, only a few bacterial (e.g. xanthan, levan, dextran) and fungal (e.g. pullulan) EPS have reached full commercialization. During the last years, other microbial EPS producers have been the subject of extensive research, including endophytes, extremophiles, microalgae and Cyanobacteria, as well as mixed microbial consortia. Those studies have demonstrated the great potential of such microbial systems to generate biopolymers with novel chemical structures and distinctive functional properties. In this work, an overview of the bioprocesses developed for EPS production by the wide diversity of reported microbial producers is presented, including their development and scale-up. Bottlenecks that currently hinder microbial EPS development are identified, along with future prospects for further advancement.
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Affiliation(s)
- Filomena Freitas
- UCIBIO-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Cristiana A V Torres
- UCIBIO-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Maria A M Reis
- UCIBIO-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
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Kumka JE, Schindel H, Fang M, Zappa S, Bauer CE. Transcriptomic analysis of aerobic respiratory and anaerobic photosynthetic states in Rhodobacter capsulatus and their modulation by global redox regulators RegA, FnrL and CrtJ. Microb Genom 2017; 3:e000125. [PMID: 29114403 PMCID: PMC5643017 DOI: 10.1099/mgen.0.000125] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 06/19/2017] [Indexed: 01/09/2023] Open
Abstract
Anoxygenicphotosynthetic prokaryotes have simplified photosystems that represent ancient lineages that predate the more complex oxygen evolving photosystems present in cyanobacteria and chloroplasts. These organisms thrive under illuminated anaerobic photosynthetic conditions, but also have the ability to grow under dark aerobic respiratory conditions. This study provides a detailed snapshot of transcription ground states of both dark aerobic and anaerobic photosynthetic growth modes in the purple photosynthetic bacterium Rhodobactercapsulatus. Using 18 biological replicates for aerobic and photosynthetic states, we observed that 1834 genes (53 % of the genome) exhibited altered expression between aerobic and anaerobic growth. In comparison with aerobically grown cells, photosynthetically grown anaerobic cells showed decreased transcription of genes for cobalamin biosynthesis (-45 %), iron transport and homeostasis (-42 %), motility (-32 %), and glycolysis (-34 %). Conversely and more intuitively, the expression of genes involved in carbon fixation (547 %), bacteriochlorophyll biosynthesis (162 %) and carotenogenesis (114 %) were induced. We also analysed the relative contributions of known global redox transcription factors RegA, FnrL and CrtJ in regulating aerobic and anaerobic growth. Approximately 50 % of differentially expressed genes (913 of 1834) were affected by a deletion of RegA, while 33 % (598 out of 1834) were affected by FnrL, and just 7 % (136 out of 1834) by CrtJ. Numerous genes were also shown to be controlled by more than one redox responding regulator.
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Affiliation(s)
- Joseph E. Kumka
- Molecular and Cellular Biochemistry, Indiana University, Bloomington, USA
| | - Heidi Schindel
- Molecular and Cellular Biochemistry, Indiana University, Bloomington, USA
| | - Mingxu Fang
- Molecular and Cellular Biochemistry, Indiana University, Bloomington, USA
| | - Sebastien Zappa
- Molecular and Cellular Biochemistry, Indiana University, Bloomington, USA
| | - Carl E. Bauer
- Biochemistry, Indiana University Bloomington, Simon Hall MSB, 212 S Hawthorne Dr, Bloomington, IN 47405-7003, USA
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Quiroz-Rocha E, Bonilla-Badía F, García-Aguilar V, López-Pliego L, Serrano-Román J, Cocotl-Yañez M, Guzmán J, Ahumada-Manuel CL, Muriel-Millán LF, Castañeda M, Espín G, Nuñez C. Two-component system CbrA/CbrB controls alginate production in Azotobacter vinelandii. MICROBIOLOGY-SGM 2017; 163:1105-1115. [PMID: 28699871 DOI: 10.1099/mic.0.000457] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Azotobacter vinelandii, belonging to the Pseudomonadaceae family, is a free-living bacterium that has been considered to be a good source for the production of bacterial polymers such as alginate. In A. vinelandii the synthesis of this polymer is regulated by the Gac/Rsm post-transcriptional regulatory system, in which the RsmA protein binds to the mRNA of the biosynthetic algD gene, inhibiting translation. In several Pseudomonas spp. the two-component system CbrA/CbrB has been described to control a variety of metabolic and behavioural traits needed for adaptation to changing environmental conditions. In this work, we show that the A. vinelandii CbrA/CbrB two-component system negatively affects alginate synthesis, a function that has not been described in Pseudomonas aeruginosa or any other Pseudomonas species. CbrA/CbrB was found to control the expression of some alginate biosynthetic genes, mainly algD translation. In agreement with this result, the CbrA/CbrB system was necessary for optimal rsmA expression levels. CbrA/CbrB was also required for maximum accumulation of the sigma factor RpoS. This last effect could explain the positive effect of CbrA/CbrB on rsmA expression, as we also showed that one of the promoters driving rsmA transcription was RpoS-dependent. However, although inactivation of rpoS increased alginate production by almost 100 %, a cbrA mutation increased the synthesis of this polymer by up to 500 %, implying the existence of additional CbrA/CbrB regulatory pathways for the control of alginate production. The control exerted by CbrA/CbrB on the expression of the RsmA protein indicates the central role of this system in regulating carbon metabolism in A. vinelandii.
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Affiliation(s)
- Elva Quiroz-Rocha
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México
| | - Fernando Bonilla-Badía
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México.,Present address: Departamento de Medicina, Centro Interdisciplinario de Ciencias de la Salud-Unidad Milpa Alta, Instituto Politécnico Nacional, CICITEC, Ex-Hacienda del Mayorazgo, Km. 39.5 Carretera Xochimilco - Oaxtepec, Ciudad de México, CP 12000, México
| | - Valentina García-Aguilar
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Apdo. Postal 1622, CP 72000, México
| | - Liliana López-Pliego
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Apdo. Postal 1622, CP 72000, México
| | - Jade Serrano-Román
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México
| | - Miguel Cocotl-Yañez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México.,Present address: Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, CP 04510, México
| | - Josefina Guzmán
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México
| | - Carlos L Ahumada-Manuel
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México
| | - Luis Felipe Muriel-Millán
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México
| | - Miguel Castañeda
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Apdo. Postal 1622, CP 72000, México
| | - Guadalupe Espín
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México
| | - Cinthia Nuñez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col Chamilpa, Cuernavaca, Morelos, CP 62210, México
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Eberhart LJ, Knutson CM, Barney BM. A methodology for markerless genetic modifications in Azotobacter vinelandii. J Appl Microbiol 2017; 120:1595-604. [PMID: 26854474 DOI: 10.1111/jam.13091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 01/29/2016] [Accepted: 01/30/2016] [Indexed: 01/03/2023]
Abstract
AIMS Efficient manipulation of multiple regions within a genome can be improved by counter-selection approaches. In this work, we sought to develop a method to manipulate Azotobacter vinelandii using a counter-selection approach based on the presence of the pyrF gene. METHODS AND RESULTS A background uracil auxotroph of A. vinelandii was first constructed by deleting the pyrF gene coding orotidine-5'-phosphate decarboxylase. The pyrF gene and promoter were also incorporated together with an antibiotic marker to create a selection and counter-selection cassette to shuttle into various plasmids. The constructed cassette could then be removed using a plasmid lacking the pyrF gene via counter-selection resulting from the production of 5-fluorouracil. The process could be repeated multiple times using the same procedure for selection and counter-selection. Following completion, the pyrF gene may be reintroduced to the genome in its original location, leaving a completed strain devoid of any antibiotic markers. CONCLUSIONS Utilization of the pyrF gene for counter-selection is a powerful tool that can be used effectively to make multiple gene deletions in A. vinelandii. SIGNIFICANCE AND IMPACT OF THE STUDY This study demonstrates the successful application of a counter-selection approach to yield markerless genetic modifications to A. vinelandii, which should be of interest for a range of applications in this important model bacterium.
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Affiliation(s)
- L J Eberhart
- Department of Bioproducts and Biosystems Engineering, Biotechnology Institute, University of Minnesota, St. Paul, MN, USA
| | - C M Knutson
- Department of Bioproducts and Biosystems Engineering, Biotechnology Institute, University of Minnesota, St. Paul, MN, USA
| | - B M Barney
- Department of Bioproducts and Biosystems Engineering, Biotechnology Institute, University of Minnesota, St. Paul, MN, USA
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Glucose uptake in Azotobacter vinelandii occurs through a GluP transporter that is under the control of the CbrA/CbrB and Hfq-Crc systems. Sci Rep 2017; 7:858. [PMID: 28404995 PMCID: PMC5429807 DOI: 10.1038/s41598-017-00980-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/22/2017] [Indexed: 12/03/2022] Open
Abstract
Azotobacter vinelandii, a strict aerobic, nitrogen fixing bacterium in the Pseudomonadaceae family, exhibits a preferential use of acetate over glucose as a carbon source. In this study, we show that GluP (Avin04150), annotated as an H+-coupled glucose-galactose symporter, is the glucose transporter in A. vinelandii. This protein, which is widely distributed in bacteria and archaea, is uncommon in Pseudomonas species. We found that expression of gluP was under catabolite repression control thorugh the CbrA/CbrB and Crc/Hfq regulatory systems, which were functionally conserved between A. vinelandii and Pseudomonas species. While the histidine kinase CbrA was essential for glucose utilization, over-expression of the Crc protein arrested cell growth when glucose was the sole carbon source. Crc and Hfq proteins from either A. vinelandii or P. putida could form a stable complex with an RNA A-rich Hfq-binding motif present in the leader region of gluP mRNA. Moreover, in P. putida, the gluP A-rich Hfq-binding motif was functional and promoted translational inhibition of a lacZ reporter gene. The fact that gluP is not widely distributed in the Pseudomonas genus but is under control of the CbrA/CbrB and Crc/Hfq systems demonstrates the relevance of these systems in regulating metabolism in the Pseudomonadaceae family.
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Bonartseva GA, Akulina EA, Myshkina VL, Voinova VV, Makhina TK, Bonartsev AP. Alginate biosynthesis by Azotobacter bacteria. APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s0003683817010070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Muriel-Millán LF, Moreno S, Gallegos-Monterrosa R, Espín G. Unphosphorylated EIIA Ntr induces ClpAP-mediated degradation of RpoS in Azotobacter vinelandii. Mol Microbiol 2017; 104:197-211. [PMID: 28097724 DOI: 10.1111/mmi.13621] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2017] [Indexed: 02/02/2023]
Abstract
The nitrogen-related phosphotransferase system (PTSNtr ) is composed of the EINtr , NPr and EIIANtr proteins that form a phosphorylation cascade from phosphoenolpyruvate. PTSNtr is a global regulatory system present in most Gram-negative bacteria that controls some pivotal processes such as potassium and phosphate homeostasis, virulence, nitrogen fixation and ABC transport activation. In the soil bacterium Azotobacter vinelandii, unphosphorylated EIIANtr negatively regulates the expression of genes related to the synthesis of the bioplastic polyester poly-β-hydroxybutyrate (PHB) and cyst-specific lipids alkylresorcinols (ARs). The mechanism by which EIIANtr controls gene expression in A. vinelandii is not known. Here, we show that, in presence of unphosphorylated EIIANtr , the stability of the stationary phase sigma factor RpoS, which is necessary for transcriptional activation of PHB and ARs synthesis related genes, is reduced, and that the inactivation of genes coding for ClpAP protease complex in strains that carry unphosphorylated EIIANtr , restored the levels and in vivo stability of RpoS, as well as the synthesis of PHB and ARs. Taken together, our results reveal a novel mechanism, by which EIIANtr globally controls gene expression in A. vinelandii, where the unphosphorylated EIIANtr induces the degradation of RpoS by the proteolytic complex ClpAP.
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Affiliation(s)
- Luis Felipe Muriel-Millán
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, 62210, México
| | - Soledad Moreno
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, 62210, México
| | - Ramsés Gallegos-Monterrosa
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, 62210, México
| | - Guadalupe Espín
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, 62210, México
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The signaling protein MucG negatively affects the production and the molecular mass of alginate in Azotobacter vinelandii. Appl Microbiol Biotechnol 2016; 101:1521-1534. [PMID: 27796435 DOI: 10.1007/s00253-016-7931-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Revised: 10/03/2016] [Accepted: 10/10/2016] [Indexed: 10/20/2022]
Abstract
Azotobacter vinelandii is a soil bacterium that produces the polysaccharide alginate. In this work, we identified a miniTn5 mutant, named GG9, which showed increased alginate production of higher molecular mass, and increased expression of the alginate biosynthetic genes algD and alg8 when compared to its parental strain. The miniTn5 was inserted within ORF Avin07920 encoding a hypothetical protein. Avin07910, located immediately downstream and predicted to form an operon with Avin07920, encodes an inner membrane multi-domain signaling protein here named mucG. Insertional inactivation of mucG resulted in a phenotype of increased alginate production of higher molecular mass similar to that of mutant GG9. The MucG protein contains a periplasmic and putative HAMP and PAS domains, which are linked to GGDEF and EAL domains. The last two domains are potentially involved in the synthesis and degradation, respectively, of bis-(3'-5')-cyclic dimeric GMP (c-di-GMP), a secondary messenger that has been reported to be essential for alginate production. Therefore, we hypothesized that the negative effect of MucG on the production of this polymer could be explained by the putative phosphodiesterase activity of the EAL domain. Indeed, we found that alanine replacement mutagenesis of the MucG EAL motif or deletion of the entire EAL domain resulted in increased alginate production of higher molecular mass similar to the GG9 and mucG mutants. To our knowledge, this is the first reported protein that simultaneous affects the production of alginate and its molecular mass.
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Smith MJ, Francis MB. A Designed A. vinelandii-S. elongatus Coculture for Chemical Photoproduction from Air, Water, Phosphate, and Trace Metals. ACS Synth Biol 2016; 5:955-61. [PMID: 27232890 DOI: 10.1021/acssynbio.6b00107] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Microbial mutualisms play critical roles in a diverse number of ecosystems and have the potential to improve the efficiency of bioproduction for desirable chemicals. We investigate the growth of a photosynthetic cyanobacterium, Synechococcus elongatus PCC 7942, and a diazotroph, Azotobacter vinelandii, in coculture. From initial studies of the coculture grown in media with glutamate, we proposed a model of cross-feeding between these organisms. We then engineer a new microbial mutualism between Azotobacter vinelandii AV3 and cscB Synechococcus elongatus that grows in the absence of fixed carbon or nitrogen. The coculture cannot grow in the absence of a sucrose-exporting S. elongatus, and neither organism can grow alone without fixed carbon or nitrogen. This new system has the potential to produce industrially relevant products, such as polyhydroxybutyrate (PHB) and alginate, from air, water, phosphate, trace metals, and sunlight. We demonstrate the ability of the coculture to produce PHB in this work.
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Affiliation(s)
- Matthew J. Smith
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Matthew B. Francis
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
- The
Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratories, Berkeley, California 94720-1460, United States
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Analysis of respiratory activity and carbon usage of a mutant of Azotobacter vinelandii impaired in poly-β-hydroxybutyrate synthesis. J Ind Microbiol Biotechnol 2016; 43:1167-74. [PMID: 27154760 DOI: 10.1007/s10295-016-1774-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 04/11/2016] [Indexed: 10/21/2022]
Abstract
In this study, the respiratory activity and carbon usage of the mutant strain of A. vinelandii AT6, impaired in poly-β-hydroxybutyrate (PHB) production, and their relationship with the synthesis of alginate were evaluated. The alginate yield and the specific oxygen uptake rate were higher (2.5-fold and 62 %, respectively) for the AT6 strain, compared to the control strain (ATCC 9046), both in shake flasks cultures and in bioreactor, under fixed dissolved oxygen tension (1 %). In contrast, the degree of acetylation was similar in both strains. These results, together with the analysis of carbon usage (% C-mol), suggest that in the case of the AT6 strain, the flux of acetyl-CoA (precursor molecule for PHB biosynthesis and alginate acetylation) was diverted to the respiratory chain passing through the tricarboxylic acids cycle, and an important % C-mol was directed through alginate biosynthesis, up to 25.9 % and to a lesser extent, to biomass production (19.7 %).
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Huerta JM, Aguilar I, López-Pliego L, Fuentes-Ramírez LE, Castañeda M. The Role of the ncRNA RgsA in the Oxidative Stress Response and Biofilm Formation in Azotobacter vinelandii. Curr Microbiol 2016; 72:671-9. [PMID: 26858204 DOI: 10.1007/s00284-016-1003-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/27/2015] [Indexed: 12/23/2022]
Abstract
Azotobacter vinelandii is a soil bacterium that forms desiccation-resistant cysts, and the exopolysaccharide alginate is essential for this process. A. vinelandii also produces alginate under vegetative growth conditions, and this production has biotechnological significance. Poly-β-hydroxybutyrate (PHB) is another polymer synthetized by A. vinelandii that is of biotechnological interest. The GacS/A two-component signal transduction system plays an important role in regulating alginate production, PHB synthesis, and encystment. GacS/A in turn controls other important regulators such as RpoS and the ncRNAs that belong to the Rsm family. In A. vinelandii, RpoS is necessary for resisting oxidative stress as a result of its control over the expression of the catalase Kat1. In this work, we characterized a new ncRNA in A. vinelandii that is homologous to the P16/RsgA reported in Pseudomonas. We found that the expression of rgsA is regulated by GacA and RpoS and that it was essential for oxidative stress resistance. However, the activity of the catalase Kat1 is unaffected in rgsA mutants. Unlike those reported in Pseudomonas, RgsA in A. vinelandii regulates biofilm formation but not polymer synthesis or the encystment process.
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Affiliation(s)
- Jesús Manuel Huerta
- CICM-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Israel Aguilar
- CICM-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Liliana López-Pliego
- CICM-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | | | - Miguel Castañeda
- CICM-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.
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Alginate Biosynthesis inAzotobacter vinelandii: Overview of Molecular Mechanisms in Connection with the Oxygen Availability. INT J POLYM SCI 2016. [DOI: 10.1155/2016/2062360] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Gram-negative bacteriumAzotobacter vinelandiican synthetize the biopolymer alginate that has material properties appropriate for plenty of applications in industry as well as in medicine. In order to settle the foundation for improving alginate production without compromising its quality, a better understanding of the polymer biosynthesis and the mechanism of regulation during fermentation processes is necessary. This knowledge is crucial for the development of novel production strategies. Here, we highlight the key aspects of alginate biosynthesis that can lead to producing an alginate with specific material properties with particular focus on the role of oxygen availability linked with the molecular mechanisms involved in the alginate production.
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de Reese J, Sperl N, Schmid J, Sieber V, Plank J. Effect of biotechnologically modified alginates on LDH structures. BIOINSPIRED BIOMIMETIC AND NANOBIOMATERIALS 2015. [DOI: 10.1680/jbibn.14.00032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Four alginates possessing different guluronic/mannuronic acid ratios and one acetylated alginate were investigated with respect to their behaviour during intercalation into layered double hydroxides (LDHs). Two alginates were commercial products while the others were synthesised by way of bacterial fermentation and in one sample followed by enzymatic treatment. Intercalation was performed by way of co-precipitation of aluminium nitrate and zinc nitrate in alginate solution at a pH of 8·5–9. The products were characterised by powder X-ray diffraction, elemental analysis, wide-angle X-ray scattering, scanning electron microscopy and magic angle spinning (MAS) NMR spectroscopy. All alginates intercalate well into the Zn2Al-LDH host structure. With an increase in the content of guluronic acid in the alginate, the d-spacing (interlayer distance) in the alginate-LDH compound increases from 1·28 to 1·85 nm. Similarly, acetylation of the carboxylic groups leads to an increased steric volume of such alginate and therefore to a higher d-spacing (1·72 nm). The results indicate that different guluronic/mannuronic acid ratios can be used to trigger the steric size of the alginates and consequently the d-spacing of the alginate-LDHs. 13C CP MAS NMR spectroscopy confirmed an interaction between the carboxylic groups present in the alginate with the inorganic main layer.
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Affiliation(s)
- Johanna de Reese
- Chair for Construction Chemicals, Technische Universität München, Garching, Germany
| | - Nadine Sperl
- Chair of Chemistry of Biogenic Resources, Technische Universität München, Straubing, Germany
| | - Jochen Schmid
- Chair of Chemistry of Biogenic Resources, Technische Universität München, Straubing, Germany
| | - Volker Sieber
- Chair of Chemistry of Biogenic Resources, Technische Universität München, Straubing, Germany
| | - Johann Plank
- Chair for Construction Chemicals, Technische Universität München, Garching, Germany
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Schmid J, Sieber V, Rehm B. Bacterial exopolysaccharides: biosynthesis pathways and engineering strategies. Front Microbiol 2015; 6:496. [PMID: 26074894 PMCID: PMC4443731 DOI: 10.3389/fmicb.2015.00496] [Citation(s) in RCA: 306] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 05/06/2015] [Indexed: 12/13/2022] Open
Abstract
Bacteria produce a wide range of exopolysaccharides which are synthesized via different biosynthesis pathways. The genes responsible for synthesis are often clustered within the genome of the respective production organism. A better understanding of the fundamental processes involved in exopolysaccharide biosynthesis and the regulation of these processes is critical toward genetic, metabolic and protein-engineering approaches to produce tailor-made polymers. These designer polymers will exhibit superior material properties targeting medical and industrial applications. Exploiting the natural design space for production of a variety of biopolymer will open up a range of new applications. Here, we summarize the key aspects of microbial exopolysaccharide biosynthesis and highlight the latest engineering approaches toward the production of tailor-made variants with the potential to be used as valuable renewable and high-performance products for medical and industrial applications.
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Affiliation(s)
- Jochen Schmid
- Chair of Chemistry of Biogenic Resources, Technische Universität MünchenStraubing, Germany
| | - Volker Sieber
- Chair of Chemistry of Biogenic Resources, Technische Universität MünchenStraubing, Germany
| | - Bernd Rehm
- Institute of Fundamental Sciences, Massey UniversityPalmerston North, New Zealand
- The MacDiarmid Institute for Advanced Materials and NanotechnologyPalmerston North, New Zealand
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Abstract
The molecular mechanisms of alginate polymerization/modification/secretion by a proposed envelope-spanning multiprotein complex are unknown. Here, bacterial two-hybrid assays and pulldown experiments showed that the catalytic subunit Alg8 directly interacts with the proposed copolymerase Alg44 while embedded in the cytoplasmic membrane. Alg44 additionally interacts with the lipoprotein AlgK bridging the periplasmic space. Site-specific mutagenesis of Alg44 showed that protein-protein interactions and stability were independent of conserved amino acid residues R17 and R21, which are involved in c-di-GMP binding, the N-terminal PilZ domain, and the C-terminal 26 amino acids. Site-specific mutagenesis was employed to investigate the c-di-GMP-mediated activation of alginate polymerization by the PilZAlg44 domain and Alg8. Activation was found to be different from the proposed activation mechanism for cellulose synthesis. The interactive role of Alg8, Alg44, AlgG (epimerase), and AlgX (acetyltransferase) on alginate polymerization and modification was studied by using site-specific deletion mutants, inactive variants, and overproduction of subunits. The compositions, molecular masses, and material properties of resulting novel alginates were analyzed. The molecular mass was reduced by epimerization, while it was increased by acetylation. Interestingly, when overproduced, Alg44, AlgG, and the nonepimerizing variant AlgG(D324A) increased the degree of acetylation, while epimerization was enhanced by AlgX and its nonacetylating variant AlgX(S269A). Biofilm architecture analysis showed that acetyl groups promoted cell aggregation while nonacetylated polymannuronate alginate promoted stigmergy. Overall, this study sheds new light on the arrangement of the multiprotein complex involved in alginate production. Furthermore, the activation mechanism and the interplay between polymerization and modification of alginate were elucidated. This study provides new insights into the molecular mechanisms of the synthesis of the unique polysaccharide, alginate, which not only is an important virulence factor of the opportunistic human pathogen Pseudomonas aeruginosa but also has, due to its material properties, many applications in medicine and industry. Unraveling the assembly and composition of the alginate-synthesizing and envelope-spanning multiprotein complex will be of tremendous significance for the scientific community. We identified a protein-protein interaction network inside the multiprotein complex and studied its relevance with respect to alginate polymerization/modification as well as the c-di-GMP-mediated activation mechanism. A relationship between alginate polymerization and modification was shown. Due to the role of alginate in pathogenesis as well as its unique material properties harnessed in numerous applications, results obtained in this study will aid the design and development of inhibitory drugs as well as the commercial bacterial production of tailor-made alginates.
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Yoneyama F, Yamamoto M, Hashimoto W, Murata K. Production of polyhydroxybutyrate and alginate from glycerol by Azotobacter vinelandii under nitrogen-free conditions. Bioengineered 2015; 6:209-17. [PMID: 25880041 DOI: 10.1080/21655979.2015.1040209] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Glycerol is an interesting feedstock for biomaterials such as biofuels and bioplastics because of its abundance as a by-product during biodiesel production. Here we demonstrate glycerol metabolism in the nitrogen-fixing species Azotobacter vinelandii through metabolomics and nitrogen-free bacterial production of biopolymers, such as poly-d-3-hydroxybutyrate (PHB) and alginate, from glycerol. Glycerol-3-phosphate was accumulated in A. vinelandii cells grown on glycerol to the exponential phase, and its level drastically decreased in the cells grown to the stationary growth phase. A. vinelandii also overexpressed the glycerol-3-phosphate dehydrogenase gene when it was grown on glycerol. These results indicate that glycerol was first converted to glycerol-3-phosphate by glycerol kinase. Other molecules with industrial interests, such as lactic acid and amino acids including γ-aminobutyric acid, have also been accumulated in the bacterial cells grown on glycerol. Transmission electron microscopy revealed that glycerol-grown A. vinelandii stored PHB within the cells. The PHB production level reached 33% per dry cell weight in nitrogen-free glycerol medium. When grown on glycerol, alginate-overproducing mutants generated through chemical mutagenesis produced 2-fold the amount of alginate from glycerol than the parental wild-type strain. To the best of our knowledge, this is the first report on bacterial production of biopolymers from glycerol without addition of any nitrogen source.
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Affiliation(s)
- Fuminori Yoneyama
- a Division of Food Science and Biotechnology ; Graduate School of Agriclture Kyoto University ; Uji , Kyoto , Japan
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Hoefer D, Schnepf JK, Hammer TR, Fischer M, Marquardt C. Biotechnologically produced microbial alginate dressings show enhanced gel forming capacity compared to commercial alginate dressings of marine origin. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2015; 26:162. [PMID: 25786399 DOI: 10.1007/s10856-015-5492-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 02/15/2015] [Indexed: 06/04/2023]
Abstract
Marine alginate fibre dressings are well established in wound management. Alginate fibres can absorb plenty of wound exudate due to their gel forming abilities and ion exchange. Alginates from bacteria have never been studied for medical applications so far, although the microbial polymer raises expectations for improved gelling capacity due to its unique O-acetylation. To prove the gelling capacity of bacterial alginate, we extracted the co-polymer from fermentation of the soil bacterium Azotobacter vinelandii ATCC 9046, cultivated on crude glycerol as an alternative carbon source. Bacterial alginate was isolated in high purity and extruded by a wet spinning method. Fibre structure and properties were characterised by infrared spectroscopy, NMR, GPC, scanning electron microscopy and tensile testing. The fibres could be processed into biocompatible needle web dressings, which showed more than twice the gel formation in saline compared to commercial dressings made of marine alginates. Gelled dressings of bacterial alginate formed stable hydrogels of sufficient shape and strength for wound healing applications. This work suggests that the increased gel formation of bacterial alginate from A. vinelandii may be optimal for the preparation of novel wound dressings.
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Affiliation(s)
- Dirk Hoefer
- Department of Hygiene, Environment and Medicine, Hohenstein Institutes, Schlosssteige 1, 74357, Boennigheim, Germany,
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Díaz-Barrera A, Martínez F, Guevara Pezoa F, Acevedo F. Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii. PLoS One 2014; 9:e105993. [PMID: 25162704 PMCID: PMC4146552 DOI: 10.1371/journal.pone.0105993] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 07/25/2014] [Indexed: 11/18/2022] Open
Abstract
Alginates are polysaccharides used as food additives and encapsulation agents in biotechnology, and their functional properties depend on its molecular weight. In this study, different steady-states in continuous cultures of A. vinelandii were established to determine the effect of the dilution rate (D) and the agitation rate on alginate production and expression of genes involved in alginate polymerization and depolymerization. Both, the agitation and dilution rates, determined the partitioning of the carbon utilization from sucrose into alginate and CO2 under oxygen-limiting conditions. A low D (0.07 h−1) and 500 rpm resulted in the highest carbon utilization into alginate (25%). Quantitative real-time polymerase chain reaction was used to determine the transcription level of six genes involved in alginate polymerization and depolymerization. In chemostat cultures at 0.07 h−1, the gene expression was affected by changes in the agitation rate. By increasing the agitation rate from 400 to 600 rpm, the algE7 gene expression decreased tenfold, whereas alyA1, algL and alyA2 gene expression increased between 1.5 and 2.8 times under similar conditions evaluated. Chemostat at 0.07 h−1 showed a highest alginate molecular weight (580 kDa) at 500 rpm whereas similar molecular weights (480 kDa) were obtained at 400 and 600 rpm. The highest molecular weight was not explained by changes in the expression of alg8 and alg44 (genes involved in alginate polymerization). Nonetheless, a different expression pattern observed for lyases could explain the highest alginate molecular weight obtained. Overall, the results suggest that the control of alginate molecular weight in A. vinelandii cells growing in continuous mode is determined by a balance between the gene expression of intracellular and extracellular lyases in response to oxygen availability. These findings better our understanding of the biosynthesis of bacterial alginate and help us progress toward obtain tailor-made alginates.
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Affiliation(s)
- Alvaro Díaz-Barrera
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Catolica de Valparaiso, Valparaiso, Chile
- * E-mail:
| | - Fabiola Martínez
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Catolica de Valparaiso, Valparaiso, Chile
| | - Felipe Guevara Pezoa
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Catolica de Valparaiso, Valparaiso, Chile
| | - Fernando Acevedo
- Escuela de Ingeniería Bioquímica, Pontificia Universidad Catolica de Valparaiso, Valparaiso, Chile
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García A, Segura D, Espín G, Galindo E, Castillo T, Peña C. High production of poly-β-hydroxybutyrate (PHB) by an Azotobacter vinelandii mutant altered in PHB regulation using a fed-batch fermentation process. Biochem Eng J 2014. [DOI: 10.1016/j.bej.2013.10.020] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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