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Bing RG, Willard DJ, Crosby JR, Adams MWW, Kelly RM. Whither the genus Caldicellulosiruptor and the order Thermoanaerobacterales: phylogeny, taxonomy, ecology, and phenotype. Front Microbiol 2023; 14:1212538. [PMID: 37601363 PMCID: PMC10434631 DOI: 10.3389/fmicb.2023.1212538] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/20/2023] [Indexed: 08/22/2023] Open
Abstract
The order Thermoanaerobacterales currently consists of fermentative anaerobic bacteria, including the genus Caldicellulosiruptor. Caldicellulosiruptor are represented by thirteen species; all, but one, have closed genome sequences. Interest in these extreme thermophiles has been motivated not only by their high optimal growth temperatures (≥70°C), but also by their ability to hydrolyze polysaccharides including, for some species, both xylan and microcrystalline cellulose. Caldicellulosiruptor species have been isolated from geographically diverse thermal terrestrial environments located in New Zealand, China, Russia, Iceland and North America. Evidence of their presence in other terrestrial locations is apparent from metagenomic signatures, including volcanic ash in permafrost. Here, phylogeny and taxonomy of the genus Caldicellulosiruptor was re-examined in light of new genome sequences. Based on genome analysis of 15 strains, a new order, Caldicellulosiruptorales, is proposed containing the family Caldicellulosiruptoraceae, consisting of two genera, Caldicellulosiruptor and Anaerocellum. Furthermore, the order Thermoanaerobacterales also was re-assessed, using 91 genome-sequenced strains, and should now include the family Thermoanaerobacteraceae containing the genera Thermoanaerobacter, Thermoanaerobacterium, Caldanaerobacter, the family Caldanaerobiaceae containing the genus Caldanaerobius, and the family Calorimonaceae containing the genus Calorimonas. A main outcome of ANI/AAI analysis indicates the need to reclassify several previously designated species in the Thermoanaerobacterales and Caldicellulosiruptorales by condensing them into strains of single species. Comparative genomics of carbohydrate-active enzyme inventories suggested differentiating phenotypic features, even among strains of the same species, reflecting available nutrients and ecological roles in their native biotopes.
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Affiliation(s)
- Ryan G. Bing
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, United States
| | - Daniel J. Willard
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, United States
| | - James R. Crosby
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, United States
| | - Michael W. W. Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
| | - Robert M. Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, United States
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Bing RG, Willard DJ, Manesh MJH, Laemthong T, Crosby JR, Adams MWW, Kelly RM. Complete Genome Sequences of Caldicellulosiruptor acetigenus DSM 7040, Caldicellulosiruptor morganii DSM 8990 (RT8.B8), and Caldicellulosiruptor naganoensis DSM 8991 (NA10). Microbiol Resour Announc 2023; 12:e0129222. [PMID: 36722965 PMCID: PMC10019236 DOI: 10.1128/mra.01292-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 01/20/2023] [Indexed: 02/02/2023] Open
Abstract
The genome sequences of three extremely thermophilic, lignocellulolytic Caldicellulosiruptor species were closed, improving previously reported multiple-contig assemblies. All 14 classified Caldicellulosiruptor spp. now have closed genomes. Genome closure will enhance bioinformatic analysis of the species, including identification of carbohydrate-active enzymes (CAZymes) and comparison against other Caldicellulosiruptor species and lignocellulolytic microorganisms.
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Affiliation(s)
- Ryan G. Bing
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Daniel J. Willard
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Mohamad J. H. Manesh
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Tunyaboon Laemthong
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - James R. Crosby
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Michael W. W. Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Robert M. Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
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Svetlitchnyi VA, Svetlichnaya TP, Falkenhan DA, Swinnen S, Knopp D, Läufer A. Direct conversion of cellulose to L-lactic acid by a novel thermophilic Caldicellulosiruptor strain. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:44. [PMID: 35501875 PMCID: PMC9063331 DOI: 10.1186/s13068-022-02137-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 04/14/2022] [Indexed: 11/18/2022]
Abstract
Background Consolidated bioprocessing (CBP) of lignocellulosic biomass to l-lactic acid using thermophilic cellulolytic/hemicellulolytic bacteria provides a promising solution for efficient lignocellulose conversion without the need for additional cellulolytic/hemicellulolytic enzymes. Most studies on the mesophilic and thermophilic CBP of lignocellulose to lactic acid concentrate on cultivation of non-cellulolytic mesophilic and thermophilic bacteria at temperatures of 30–55 °C with external addition of cellulases/hemicellulases for saccharification of substrates. Results l-Lactic acid was generated by fermenting microcrystalline cellulose or lignocellulosic substrates with a novel thermophilic anaerobic bacterium Caldicellulosiruptor sp. DIB 104C without adding externally produced cellulolytic/hemicellulolytic enzymes. Selection of this novel bacterium strain for lactic acid production is described as well as the adaptive evolution towards increasing the l-lactic acid concentration from 6 to 70 g/l on microcrystalline cellulose. The evolved strains grown on microcrystalline cellulose show a maximum lactic acid production rate of 1.0 g/l*h and a lactic acid ratio in the total organic fermentation products of 96 wt%. The enantiomeric purity of the l-lactic acid generated is 99.4%. In addition, the lactic acid production by these strains on several other types of cellulose and lignocellulosic feedstocks is also reported. Conclusions The evolved strains originating from Caldicellulosiruptor sp. DIB 104C were capable of producing unexpectedly large amounts of l-lactic acid from microcrystalline cellulose in fermenters. These strains produce l-lactic acid also from lignocellulosic feedstocks and thus represent an ideal starting point for development of a highly integrated commercial l-lactic acid production process from such feedstocks.
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Affiliation(s)
| | | | | | - Steve Swinnen
- BluCon Biotech GmbH, Nattermannallee 1, 50829, Cologne, Germany
| | - Daniela Knopp
- BluCon Biotech GmbH, Nattermannallee 1, 50829, Cologne, Germany
| | - Albrecht Läufer
- BluCon Biotech GmbH, Nattermannallee 1, 50829, Cologne, Germany
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Chen Y, Nishihara A, Iino T, Ohkuma M, Haruta S. Caldicellulosiruptor diazotrophicus sp. nov., a thermophilic, nitrogen-fixing fermentative bacterium isolated from a terrestrial hot spring in Japan. Int J Syst Evol Microbiol 2021; 71. [PMID: 34542397 DOI: 10.1099/ijsem.0.005014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A novel nitrogen-fixing fermentative bacterium, designated as YA01T, was isolated from Nakabusa hot springs in Japan. The short-rod cells of strain YA01T were Gram-positive and non-sporulating. Phylogenetic trees of the 16S rRNA gene sequence and concatenated sequences of 40 single-copy ribosomal genes revealed that strain YA01T belonged to the genus Caldicellulosiruptor and was closely related to Caldicellulosiruptor hydrothermalis 108T, Caldicellulosiruptor bescii DSM 6725T and Caldicellulosiruptor kronotskyensis 2002T. The 16S rRNA gene sequence of strain YA01T shares less than 98.1 % identity to the known Caldicellulosiruptor species. The G+C content of the genomic DNA was 34.8 mol%. Strain YA01T shares low genome-wide average nucleotide identity (90.31-91.10 %), average amino acid identity (91.45-92.10 %) and <70 % digital DNA-DNA hybridization value (41.8-44.2 %) with the three related species of the genus Caldicellulosiruptor. Strain YA01T grew at 50-78 °C (optimum, 70 °C) and at pH 5.0-9.5 (optimum, pH 6.5). Strain YA01T mainly produced acetate by consuming d(+)-glucose as a carbon source. The main cellular fatty acids were iso-C17 : 0 (35.7 %), C16 : 0 (33.3 %), DMA16 : 0 (6.6 %) and iso-C15 : 0 (5.9 %). Based on its distinct phylogenetic position, biochemical and physiological characteristics, and the major cellular fatty acids, strain YA01T is considered to represent a novel species of the genus Caldicellulosiruptor for which the name Caldicellulosiruptor diazotrophicus sp. nov. is proposed (type strain YA01T=DSM 112098T=JCM 34253T).
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Affiliation(s)
- Yuxin Chen
- Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Arisa Nishihara
- Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.,Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-0856, Japan
| | - Takao Iino
- Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.,Japan Collection of Microorganisms, RIKEN BioResource Research Center, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
| | - Moriya Ohkuma
- Japan Collection of Microorganisms, RIKEN BioResource Research Center, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
| | - Shin Haruta
- Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
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Bing RG, Sulis DB, Wang JP, Adams MW, Kelly RM. Thermophilic microbial deconstruction and conversion of natural and transgenic lignocellulose. ENVIRONMENTAL MICROBIOLOGY REPORTS 2021; 13:272-293. [PMID: 33684253 PMCID: PMC10519370 DOI: 10.1111/1758-2229.12943] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/25/2021] [Accepted: 02/28/2021] [Indexed: 06/12/2023]
Abstract
The potential to convert renewable plant biomasses into fuels and chemicals by microbial processes presents an attractive, less environmentally intense alternative to conventional routes based on fossil fuels. This would best be done with microbes that natively deconstruct lignocellulose and concomitantly form industrially relevant products, but these two physiological and metabolic features are rarely and simultaneously observed in nature. Genetic modification of both plant feedstocks and microbes can be used to increase lignocellulose deconstruction capability and generate industrially relevant products. Separate efforts on plants and microbes are ongoing, but these studies lack a focus on optimal, complementary combinations of these disparate biological systems to obtain a convergent technology. Improving genetic tools for plants have given rise to the generation of low-lignin lines that are more readily solubilized by microorganisms. Most focus on the microbiological front has involved thermophilic bacteria from the genera Caldicellulosiruptor and Clostridium, given their capacity to degrade lignocellulose and to form bio-products through metabolic engineering strategies enabled by ever-improving molecular genetics tools. Bioengineering plant properties to better fit the deconstruction capabilities of candidate consolidated bioprocessing microorganisms has potential to achieve the efficient lignocellulose deconstruction needed for industrial relevance.
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Affiliation(s)
- Ryan G. Bing
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695
| | - Daniel B. Sulis
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695
| | - Jack P. Wang
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695
| | - Michael W.W. Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Robert M. Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695
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Vongkampang T, Sreenivas K, Engvall J, Grey C, van Niel EWJ. Characterization of simultaneous uptake of xylose and glucose in Caldicellulosiruptor kronotskyensis for optimal hydrogen production. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:91. [PMID: 33832529 PMCID: PMC8034154 DOI: 10.1186/s13068-021-01938-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 03/22/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Caldicellulosiruptor kronotskyensis has gained interest for its ability to grow on various lignocellulosic biomass. The aim of this study was to investigate the growth profiles of C. kronotskyensis in the presence of mixtures of glucose-xylose. Recently, we characterized a diauxic-like pattern for C. saccharolyticus on lignocellulosic sugar mixtures. In this study, we aimed to investigate further whether C. kronotskyensis has adapted to uptake glucose in the disaccharide form (cellobiose) rather than the monosaccharide (glucose). RESULTS Interestingly, growth of C. kronotskyensis on glucose and xylose mixtures did not display diauxic-like growth patterns. Closer investigation revealed that, in contrast to C. saccharolyticus, C. kronotskyensis does not possess a second uptake system for glucose. Both C. saccharolyticus and C. kronotskyensis share the characteristics of preferring xylose over glucose. Growth on xylose was twice as fast (μmax = 0.57 h-1) as on glucose (μmax = 0.28 h-1). A study of the sugar uptake was made with different glucose-xylose ratios to find a kinetic relationship between the two sugars for transport into the cell. High concentrations of glucose inhibited xylose uptake and vice versa. The inhibition constants were estimated to be KI,glu = 0.01 cmol L-1 and KI,xyl = 0.001 cmol L-1, hence glucose uptake was more severely inhibited by xylose uptake. Bioinformatics analysis could not exclude that C. kronotskyensis possesses more than one transporter for glucose. As a next step it was investigated whether glucose uptake by C. kronotskyensis improved in the form of cellobiose. Indeed, cellobiose is taken up faster than glucose; nevertheless, the growth rate on each sugar remained similar. CONCLUSIONS C. kronotskyensis possesses a xylose transporter that might take up glucose at an inferior rate even in the absence of xylose. Alternatively, glucose can be taken up in the form of cellobiose, but growth performance is still inferior to growth on xylose. Therefore, we propose that the catabolism of C. kronotskyensis has adapted more strongly to pentose rather than hexose, thereby having obtained a specific survival edge in thermophilic lignocellulosic degradation communities.
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Affiliation(s)
- Thitiwut Vongkampang
- Division of Applied Microbiology, Lund University, P.O. Box 124, 221 00, Lund, Sweden.
| | - Krishnan Sreenivas
- Division of Applied Microbiology, Lund University, P.O. Box 124, 221 00, Lund, Sweden
| | - Jonathan Engvall
- Division of Applied Microbiology, Lund University, P.O. Box 124, 221 00, Lund, Sweden
| | - Carl Grey
- Division of Biotechnology, Lund University, P.O. Box 124, 221 00, Lund, Sweden
| | - Ed W J van Niel
- Division of Applied Microbiology, Lund University, P.O. Box 124, 221 00, Lund, Sweden
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Chen Y, Nishihara A, Haruta S. Nitrogen-fixing Ability and Nitrogen Fixation-related Genes of Thermophilic Fermentative Bacteria in the Genus Caldicellulosiruptor. Microbes Environ 2021; 36. [PMID: 34108360 PMCID: PMC8209448 DOI: 10.1264/jsme2.me21018] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Fermentative nitrogen-fixing bacteria have not yet been examined in detail in thermal environments. In the present study, we isolated the thermophilic fermentative bacterium, strain YA01 from a hot spring. This strain grew at temperatures up to 78°C. A phylogenetic analysis based on its 16S rRNA gene sequence indicated that strain YA01 belonged to the genus Caldicellulosiruptor, which are fermentative bacteria in the phylum Firmicutes, with 97.7–98.0% sequence identity to its closest relatives. Strain YA01 clearly exhibited N2-dependent growth at 70°C. We also confirmed N2-dependent growth in the relatives of strain YA01, Caldicellulosiruptor hydrothermalis 108 and Caldicellulosiruptor kronotskyensis 2002. The nitrogenase activities of these three strains were examined using the acetylene reduction assay. Similar activities were detected for all tested strains, and were slightly suppressed by the addition of ammonium. A genome analysis revealed that strain YA01, as well as other Caldicellulosiruptor, possessed a gene set for nitrogen fixation, but lacked the nifN gene, which encodes a nitrogenase iron-molybdenum cofactor biosynthesis protein that is commonly detected in nitrogen-fixing bacteria. The amino acid sequences of nitrogenase encoded by nifH, nifD, and nifK shared 92–98% similarity in Caldicellulosiruptor. A phylogenetic tree of concatenated NifHDK sequences showed that NifHDK of Caldicellulosiruptor was in the deepest clade. To the best of our knowledge, this is the first study to demonstrate the nitrogen-fixing ability of fermentative bacteria at 70°C. Caldicellulosiruptor may have retained an ancient nitrogen-fixing enzyme system.
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Affiliation(s)
- Yuxin Chen
- Department of Biological Sciences, Tokyo Metropolitan University
| | - Arisa Nishihara
- Department of Biological Sciences, Tokyo Metropolitan University.,Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
| | - Shin Haruta
- Department of Biological Sciences, Tokyo Metropolitan University
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Singh N, Mathur AS, Gupta RP, Barrow CJ, Tuli DK, Puri M. Enzyme systems of thermophilic anaerobic bacteria for lignocellulosic biomass conversion. Int J Biol Macromol 2020; 168:572-590. [PMID: 33309672 DOI: 10.1016/j.ijbiomac.2020.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 11/17/2022]
Abstract
Economic production of lignocellulose degrading enzymes for biofuel industries is of considerable interest to the biotechnology community. While these enzymes are widely distributed in fungi, their industrial production from other sources, particularly by thermophilic anaerobic bacteria (growth Topt ≥ 60 °C), is an emerging field. Thermophilic anaerobic bacteria produce a large number of lignocellulolytic enzymes having unique structural features and employ different schemes for biomass degradation, which can be classified into four systems namely; 'free enzyme system', 'cell anchored enzymes', 'complex cellulosome system', and 'multifunctional multimodular enzyme system'. Such enzymes exhibit high specific activity and have a natural ability to withstand harsh bioprocessing conditions. However, achieving a higher production of these thermostable enzymes at current bioprocessing targets is challenging. In this review, the research opportunities for these distinct enzyme systems in the biofuel industry and the associated technological challenges are discussed. The current status of research findings is highlighted along with a detailed description of the categorization of the different enzyme production schemes. It is anticipated that high temperature-based bioprocessing will become an integral part of sustainable bioenergy production in the near future.
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Affiliation(s)
- Nisha Singh
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Victoria 3217, Australia; DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Anshu S Mathur
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Ravi P Gupta
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Colin J Barrow
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Victoria 3217, Australia
| | - Deepak K Tuli
- DBT-IOC Centre for Advance Bioenergy Research, Research & Development Centre, Indian Oil Corporation Limited, Sector-13, Faridabad 121007, India
| | - Munish Puri
- Centre for Chemistry and Biotechnology, Deakin University, Waurn Ponds, Victoria 3217, Australia; Medical Biotechnology, Centre for Marine Bioproducts Development, College of Medicine and Public Health, Flinders University, Bedford Park, Adelaide 5042, Australia.
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