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Berezina OV, Rykov SV, Schwarz WH, Liebl W. Xanthan: enzymatic degradation and novel perspectives of applications. Appl Microbiol Biotechnol 2024; 108:227. [PMID: 38381223 PMCID: PMC10881899 DOI: 10.1007/s00253-024-13016-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 01/04/2024] [Accepted: 01/11/2024] [Indexed: 02/22/2024]
Abstract
The extracellular heteropolysaccharide xanthan, synthesized by bacteria of the genus Xanthomonas, is widely used as a thickening and stabilizing agent across the food, cosmetic, and pharmaceutical sectors. Expanding the scope of its application, current efforts target the use of xanthan to develop innovative functional materials and products, such as edible films, eco-friendly oil surfactants, and biocompatible composites for tissue engineering. Xanthan-derived oligosaccharides are useful as nutritional supplements and plant defense elicitors. Development and processing of such new functional materials and products often necessitate tuning of xanthan properties through targeted structural modification. This task can be effectively carried out with the help of xanthan-specific enzymes. However, the complex molecular structure and intricate conformational behavior of xanthan create problems with its enzymatic hydrolysis or modification. This review summarizes and analyzes data concerning xanthan-degrading enzymes originating from microorganisms and microbial consortia, with a particular focus on the dependence of enzymatic activity on the structure and conformation of xanthan. Through a comparative study of xanthan-degrading pathways found within various bacterial classes, different microbial enzyme systems for xanthan utilization have been identified. The characterization of these new enzymes opens new perspectives for modifying xanthan structure and developing innovative xanthan-based applications. KEY POINTS: • The structure and conformation of xanthan affect enzymatic degradation. • Microorganisms use diverse multienzyme systems for xanthan degradation. • Xanthan-specific enzymes can be used to develop xanthan variants for novel applications.
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Affiliation(s)
- Oksana V Berezina
- National Research Centre «Kurchatov Institute», Academician Kurchatov Sq. 1, 123182, Moscow, Russian Federation
| | - Sergey V Rykov
- National Research Centre «Kurchatov Institute», Academician Kurchatov Sq. 1, 123182, Moscow, Russian Federation
| | - Wolfgang H Schwarz
- Chair of Microbiology, Technical University of Munich, TUM School of Life Sciences, Emil-Ramann-Str. 4, 85354, Freising, Germany
| | - Wolfgang Liebl
- Chair of Microbiology, Technical University of Munich, TUM School of Life Sciences, Emil-Ramann-Str. 4, 85354, Freising, Germany.
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Podosokorskaya OA, Elcheninov AG, Novikov AA, Merkel AY, Kublanov IV. Fontisphaera persica gen. nov., sp. nov., a thermophilic hydrolytic bacterium from a hot spring of Baikal lake region, and proposal of Fontisphaeraceae fam. nov., and Limisphaeraceae fam. nov. within the Limisphaerales ord. nov. (Verrucomicrobiota). Syst Appl Microbiol 2023; 46:126438. [PMID: 37263084 DOI: 10.1016/j.syapm.2023.126438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/25/2023] [Accepted: 05/24/2023] [Indexed: 06/03/2023]
Abstract
A novel facultatively anaerobic moderately thermophilic bacterium, strain B-154 T, was isolated from a terrestrial hot spring in the Baikal lake region (Russian Federation). Gram-negative, motile, spherical cells were present singly, in pairs, or aggregates, and reproduced by binary fission. The strain grew at 30-57 °C and within a pH range of 5.1-8.4 with the optimum at 50 °C and pH 6.8-7.1. Strain B-154 T was a chemoorganoheterotroph, growing on mono-, di- and polysaccharides (xylan, starch, galactan, galactomannan, glucomannan, xyloglucan, pullulan, arabinan, lichenan, beta-glucan, pachyman, locust bean gum, xanthan gum). It did not require sodium chloride or yeast extract for growth. Major cellular fatty acids were anteiso-C15:0, iso-C16:0 and iso-C14:0. The respiratory quinone was MK-7. The complete genome of strain B-154 T was 4.73 Mbp in size; its G + C content was 61%. According to the phylogenomic analysis strain B-154 T forms a separate family-level phylogenetic lineage. Moreover, together with Limisphaera ngatamarikiensis and "Pedosphaera parvula" this strain forms a separate order-level phylogenetic lineage within Verrucomicrobiae class. Hence, we propose a novel order, Limisphaerales ord. nov., with two families Limisphaeraceae fam. nov. and Fontisphaeraceae fam. nov., and a novel genus and species Fontisphaera persica gen. nov., sp. nov. with type strain B-154 T. Ecogenomic analysis showed that representatives of the Limisphaerales are widespread in various environments. Although some of them were detected in hot springs the majority of Limisphaerales (54% of the studied metagenome-assembled genomes) were found in marine habitats. This study allowed a better understanding of physiology and ecology of Verrucomicrobiota - a rather understudied bacterial phylum.
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Affiliation(s)
- Olga A Podosokorskaya
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia.
| | - Alexander G Elcheninov
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia
| | - Andrei A Novikov
- Gubkin University, 65/1 Leninsky Prospect, 119991 Moscow, Russia
| | - Alexander Y Merkel
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia
| | - Ilya V Kublanov
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia
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Nagasawa Y, Katagiri S, Nakagawa K, Hirota T, Yoshimi K, Uchida A, Hatasa M, Komatsu K, Shiba T, Ohsugi Y, Uesaka N, Iwata T, Tohara H. Xanthan gum-based fluid thickener decreases postprandial blood glucose associated with increase of Glp1 and Glp1r expression in ileum and alteration of gut microbiome. J Funct Foods 2022. [DOI: 10.1016/j.jff.2022.105321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Podosokorskaya OA, Elcheninov AG, Novikov AA, Kublanov IV. Fontivita pretiosa gen. nov., sp. nov., a thermophilic planctomycete of the order Tepidisphaerales from a hot spring of Baikal lake region. Syst Appl Microbiol 2022; 45:126375. [DOI: 10.1016/j.syapm.2022.126375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 10/11/2022] [Accepted: 10/15/2022] [Indexed: 11/09/2022]
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Kallscheuer N, Jogler C, Peeters SH, Boedeker C, Jogler M, Heuer A, Jetten MSM, Rohde M, Wiegand S. Mucisphaera calidilacus gen. nov., sp. nov., a novel planctomycete of the class Phycisphaerae isolated in the shallow sea hydrothermal system of the Lipari Islands. Antonie van Leeuwenhoek 2022; 115:407-420. [PMID: 35050438 PMCID: PMC8882080 DOI: 10.1007/s10482-021-01707-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 12/29/2021] [Indexed: 02/07/2023]
Abstract
For extending the current collection of axenic cultures of planctomycetes, we describe in this study the isolation and characterisation of strain Pan265T obtained from a red biofilm in the hydrothermal vent system close to the Lipari Islands in the Tyrrhenian Sea, north of Sicily, Italy. The strain forms light pink colonies on solid medium and grows as a viscous colloid in liquid culture, likely as the result of formation of a dense extracellular matrix observed during electron microscopy. Cells of the novel isolate are spherical, motile and divide by binary fission. Strain Pan265T is mesophilic (temperature optimum 30-33 °C), neutrophilic (pH optimum 7.0-8.0), aerobic and heterotrophic. The strain has a genome size of 3.49 Mb and a DNA G + C content of 63.9%. Phylogenetically, the strain belongs to the family Phycisphaeraceae, order Phycisphaerales, class Phycisphaerae. Our polyphasic analysis supports the delineation of strain Pan265T from the known genera in this family. Therefore, we conclude to assign strain Pan265T to a novel species within a novel genus, for which we propose the name Mucisphaera calidilacus gen. nov., sp. nov. The novel species is the type species of the novel genus and is represented by strain Pan265T (= DSM 100697T = CECT 30425T) as type strain.
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Affiliation(s)
- Nicolai Kallscheuer
- Department of Microbiology, Radboud University, Nijmegen, The Netherlands
- Department of Microbial Interactions, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Christian Jogler
- Department of Microbiology, Radboud University, Nijmegen, The Netherlands.
- Department of Microbial Interactions, Institute of Microbiology, Friedrich Schiller University, Jena, Germany.
| | - Stijn H Peeters
- Department of Microbiology, Radboud University, Nijmegen, The Netherlands
| | | | - Mareike Jogler
- Department of Microbiology, Radboud University, Nijmegen, The Netherlands
- Department of Microbial Interactions, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Anja Heuer
- Leibniz Institute DSMZ, Braunschweig, Germany
| | - Mike S M Jetten
- Department of Microbiology, Radboud University, Nijmegen, The Netherlands
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Sandra Wiegand
- Department of Microbiology, Radboud University, Nijmegen, The Netherlands
- Institute for Biological Interfaces 5, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
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Denisenko YA, Korotkova OG, Zorov IN, Rozhkova AM, Semenova MV, Elcheninov AG, Kublanov IV, Sinitsyn AP. Heterologous Expression of Thermogutta terrifontis Endo-Xanthanase in Penicillium verruculosum, Isolation and Primary Characterization of the Enzyme. BIOCHEMISTRY (MOSCOW) 2021; 86:489-495. [PMID: 33941069 DOI: 10.1134/s000629792104009x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Heterologous endo-xanthanase (EX) from the thermophilic planktomycete Thermogutta terrifontis strain was obtained using Penicillium verruculosum 537 (ΔniaD) expression system with the cellobiohydrolase 1 gene promoter. Homogeneous EX with a molecular weight of 23.7 kDa (pI 6.5) was isolated using liquid chromatography methods. This xanthan degrading enzyme also possesses the enzymatic activity towards CM-cellulose, β-glucan, curdlan, lichenan, laminarin, galactomannan, xyloglucan but not towards p-nitrophenyl derivatives of β-D-glucose, mannose and cellobiose. The temperature and pH optima of EX were 55°C and 4.0, respectively; the enzyme exhibited 90% of its maximum activity in the temperature range 50-60°C and pH 3-5.
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Affiliation(s)
- Yury A Denisenko
- Federal Research Center "Fundamentals of Fundamental Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia.
| | - Olga G Korotkova
- Federal Research Center "Fundamentals of Fundamental Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia
| | - Ivan N Zorov
- Federal Research Center "Fundamentals of Fundamental Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia.,Department of Chemical Enzymology, Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Alexandra M Rozhkova
- Federal Research Center "Fundamentals of Fundamental Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia
| | - Margarita V Semenova
- Federal Research Center "Fundamentals of Fundamental Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia
| | - Alexandr G Elcheninov
- Federal Research Center "Fundamentals of Fundamental Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia
| | - Ilya V Kublanov
- Federal Research Center "Fundamentals of Fundamental Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia
| | - Arkady P Sinitsyn
- Federal Research Center "Fundamentals of Fundamental Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia.,Department of Chemical Enzymology, Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
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Elcheninov AG, Podosokorskaya OA, Kovaleva OL, Novikov AA, Toshchakov SV, Bonch-Osmolovskaya EA, Kublanov IV. Thermogemmata fonticola gen. nov., sp. nov., the first thermophilic planctomycete of the order Gemmatales from a Kamchatka hot spring. Syst Appl Microbiol 2020; 44:126157. [PMID: 33220635 DOI: 10.1016/j.syapm.2020.126157] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 10/21/2020] [Accepted: 11/02/2020] [Indexed: 01/08/2023]
Abstract
A novel aerobic moderately thermophilic bacterium, designated strain 2918T, was isolated from a terrestrial hot spring of Kamchatka, Russian Federation. Gram-negative, motile, spherical cells were present singly, in pairs, or aggregates, and reproduced by budding. The strain grew at 25-60°C and within a pH range of 5.0-8.0 with an optimum at 54-60°C and pH 7.5. Strain 2918T did not require sodium chloride or yeast extract for growth. It was a chemoorganoheterotroph, growing on mono-, di- and polysaccharides (starch, lichenan, galactan, arabinan, xanthan gum, beta-glucan). No growth was observed under anaerobic conditions neither in the presence of sulfur, nitrate, or thiosulfate nor without adding any electron acceptor. Major cellular fatty acids were C18:0 and C20:0. The respiratory quinone was MK-6. The size of the genome of strain 2918T was 4.81 Mb. Genomic DNA G+C content was 60.4mol%. According to the 16S rRNA gene sequence and conserved protein sequences phylogenies, strain 2918T represented a distinct lineage of the order Gemmatales within Planctomycetes. Based on phylogenetic analysis and phenotypic features, the novel isolate was assigned to a novel genus in the Gemmatales for which the name Thermogemmata gen. nov. is proposed. Strain 2918T (=KCTC 72012T =VKM B-3161T) represents its first species Thermogemmata fonticola sp. nov.
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Affiliation(s)
- Alexander G Elcheninov
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia.
| | - Olga A Podosokorskaya
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia
| | - Olga L Kovaleva
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia
| | - Andrei A Novikov
- Gubkin Russian State University of Oil and Gas, Leninskiy Prospect 65, 119991 Moscow, Russia
| | - Stepan V Toshchakov
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia
| | - Elizaveta A Bonch-Osmolovskaya
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia; Lomonosov State University, Leninskie Gory 1 Bldg 12, Moscow, Russia
| | - Ilya V Kublanov
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology RAS, 7/2 Prospekt 60-letiya Oktyabrya, 117312 Moscow, Russia
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Kulichevskaya IS, Naumoff DG, Miroshnikov KK, Ivanova AA, Philippov DA, Hakobyan A, Rijpstra WIC, Damsté JSS, Liesack W, Dedysh SN. Limnoglobus roseus gen. nov., sp. nov., a novel freshwater planctomycete with a giant genome from the family Gemmataceae. Int J Syst Evol Microbiol 2020; 70:1240-1249. [PMID: 31800383 PMCID: PMC7397252 DOI: 10.1099/ijsem.0.003904] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 11/16/2019] [Indexed: 11/18/2022] Open
Abstract
The family Gemmataceae accommodates aerobic, chemoorganotrophic planctomycetes, which inhabit various freshwater ecosystems, wetlands and soils. Here, we describe a novel member of this family, strain PX52T, which was isolated from a boreal eutrophic lake in Northern Russia. This isolate formed pink-pigmented colonies and was represented by spherical cells that occurred singly, in pairs or aggregates and multiplied by budding. Daughter cells were highly motile. PX52T was an obligate aerobic chemoorganotroph, which utilized various sugars and some heteropolysaccharides. Growth occurred at pH 5.0-7.5 (optimum pH 6.5) and at temperatures between 10 and 30 °C (optimum 20-25 °C). The major fatty acids were C18 : 1ɷ7c, C18 : 0 and βOH-C16:0; the major intact polar lipid was trimethylornithine, and the quinone was MK-6. The complete genome of PX52T was 9.38 Mb in size and contained nearly 8000 potential protein-coding genes. Among those were genes encoding a wide repertoire of carbohydrate-active enzymes (CAZymes) including 33 glycoside hydrolases (GH) and 87 glycosyltransferases (GT) affiliated with 17 and 12 CAZy families, respectively. DNA G+C content was 65.6 mol%. PX52T displayed only 86.0-89.8 % 16S rRNA gene sequence similarity to taxonomically described Gemmataceae planctomycetes and differed from them by a number of phenotypic characteristics and by fatty acid composition. We, therefore, propose to classify it as representing a novel genus and species, Limnoglobus roseus gen. nov., sp. nov. The type strain is strain PX52T (=KCTC 72397T=VKM B-3275T).
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Affiliation(s)
- Irina S. Kulichevskaya
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia
| | - Daniil G. Naumoff
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia
| | - Kirill K. Miroshnikov
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia
| | - Anastasia A. Ivanova
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia
| | - Dmitriy A. Philippov
- Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok 152742, Russia
| | - Anna Hakobyan
- Max-Planck-Institut für terrestrische Mikrobiologie, D-35043 Marburg, Germany
| | - W. Irene C. Rijpstra
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, PO Box 59, 1790 AB Den Burg, The Netherlands
- Utrecht University, Faculty of Geosciences, Department of Earth Sciences, Geochemistry, Utrecht, The Netherlands
| | - Jaap S. Sinninghe Damsté
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, PO Box 59, 1790 AB Den Burg, The Netherlands
- Utrecht University, Faculty of Geosciences, Department of Earth Sciences, Geochemistry, Utrecht, The Netherlands
| | - Werner Liesack
- Max-Planck-Institut für terrestrische Mikrobiologie, D-35043 Marburg, Germany
| | - Svetlana N. Dedysh
- Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia
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Kovaleva OL, Elcheninov AG, Toshchakov SV, Novikov AA, Bonch-Osmolovskaya EA, Kublanov IV. Tautonia sociabilis gen. nov., sp. nov., a novel thermotolerant planctomycete, isolated from a 4000 m deep subterranean habitat. Int J Syst Evol Microbiol 2019; 69:2299-2304. [DOI: 10.1099/ijsem.0.003467] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Olga L. Kovaleva
- 1Winogradsky Institute of Microbiology, Research Center of Biotechnology RAS, Moscow, Russia
| | - Alexander G. Elcheninov
- 1Winogradsky Institute of Microbiology, Research Center of Biotechnology RAS, Moscow, Russia
| | - Stepan V. Toshchakov
- 1Winogradsky Institute of Microbiology, Research Center of Biotechnology RAS, Moscow, Russia
| | - Andrei A. Novikov
- 2Department of Physical Chemistry, Gubkin University, Moscow, Russia
| | | | - Ilya V. Kublanov
- 1Winogradsky Institute of Microbiology, Research Center of Biotechnology RAS, Moscow, Russia
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Discovering novel hydrolases from hot environments. Biotechnol Adv 2018; 36:2077-2100. [PMID: 30266344 DOI: 10.1016/j.biotechadv.2018.09.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 09/21/2018] [Accepted: 09/24/2018] [Indexed: 12/12/2022]
Abstract
Novel hydrolases from hot and other extreme environments showing appropriate performance and/or novel functionalities and new approaches for their systematic screening are of great interest for developing new processes, for improving safety, health and environment issues. Existing processes could benefit as well from their properties. The workflow, based on the HotZyme project, describes a multitude of technologies and their integration from discovery to application, providing new tools for discovering, identifying and characterizing more novel thermostable hydrolases with desired functions from hot terrestrial and marine environments. To this end, hot springs worldwide were mined, resulting in hundreds of environmental samples and thousands of enrichment cultures growing on polymeric substrates of industrial interest. Using high-throughput sequencing and bioinformatics, 15 hot spring metagenomes, as well as several sequenced isolate genomes and transcriptomes were obtained. To facilitate the discovery of novel hydrolases, the annotation platform Anastasia and a whole-cell bioreporter-based functional screening method were developed. Sequence-based screening and functional screening together resulted in about 100 potentially new hydrolases of which more than a dozen have been characterized comprehensively from a biochemical and structural perspective. The characterized hydrolases include thermostable carboxylesterases, enol lactonases, quorum sensing lactonases, gluconolactonases, epoxide hydrolases, and cellulases. Apart from these novel thermostable hydrolases, the project generated an enormous amount of samples and data, thereby allowing the future discovery of even more novel enzymes.
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Fortney NW, He S, Converse BJ, Boyd ES, Roden EE. Investigating the Composition and Metabolic Potential of Microbial Communities in Chocolate Pots Hot Springs. Front Microbiol 2018; 9:2075. [PMID: 30245673 PMCID: PMC6137239 DOI: 10.3389/fmicb.2018.02075] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/14/2018] [Indexed: 01/14/2023] Open
Abstract
Iron (Fe) redox-based metabolisms likely supported life on early Earth and may support life on other Fe-rich rocky planets such as Mars. Modern systems that support active Fe redox cycling such as Chocolate Pots (CP) hot springs provide insight into how life could have functioned in such environments. Previous research demonstrated that Fe- and Si-rich and slightly acidic to circumneutral-pH springs at CP host active dissimilatory Fe(III) reducing microorganisms. However, the abundance and distribution of Fe(III)-reducing communities at CP is not well-understood, especially as they exist in situ. In addition, the potential for direct Fe(II) oxidation by lithotrophs in CP springs is understudied, in particular when compared to indirect oxidation promoted by oxygen producing Cyanobacteria. Here, a culture-independent approach, including 16S rRNA gene amplicon and shotgun metagenomic sequencing, was used to determine the distribution of putative Fe cycling microorganisms in vent fluids and sediment cores collected along the outflow channel of CP. Metagenome-assembled genomes (MAGs) of organisms native to sediment and planktonic microbial communities were screened for extracellular electron transfer (EET) systems putatively involved in Fe redox cycling and for CO2 fixation pathways. Abundant MAGs containing putative EET systems were identified as part of the sediment community at locations where Fe(III) reduction activity has previously been documented. MAGs encoding both putative EET systems and CO2 fixation pathways, inferred to be FeOB, were also present, but were less abundant components of the communities. These results suggest that the majority of the Fe(III) oxides that support in situ Fe(III) reduction are derived from abiotic oxidation. This study provides new insights into the interplay between Fe redox cycling and CO2 fixation in sustaining chemotrophic communities in CP with attendant implications for other neutral-pH hot springs.
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Affiliation(s)
- Nathaniel W. Fortney
- Department of Geoscience, NASA Astrobiology Institute, University of Wisconsin-Madison, Madison, WI, United States
| | - Shaomei He
- Department of Geoscience, NASA Astrobiology Institute, University of Wisconsin-Madison, Madison, WI, United States
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, United States
| | - Brandon J. Converse
- Department of Geoscience, NASA Astrobiology Institute, University of Wisconsin-Madison, Madison, WI, United States
| | - Eric S. Boyd
- Department of Microbiology and Immunology, NASA Astrobiology Institute, Montana State University, Bozeman, MT, United States
| | - Eric E. Roden
- Department of Geoscience, NASA Astrobiology Institute, University of Wisconsin-Madison, Madison, WI, United States
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