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Sexton D, Hashimi A, Beskrovnaya P, Sibanda L, Huan T, Tocheva E. The cell envelope of Thermotogae suggests a mechanism for outer membrane biogenesis. Proc Natl Acad Sci U S A 2023; 120:e2303275120. [PMID: 37094164 PMCID: PMC10160955 DOI: 10.1073/pnas.2303275120] [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: 03/03/2023] [Accepted: 03/29/2023] [Indexed: 04/26/2023] Open
Abstract
The presence of a cell membrane is one of the major structural components defining life. Recent phylogenomic analyses have supported the hypothesis that the last universal common ancestor (LUCA) was likely a diderm. Yet, the mechanisms that guided outer membrane (OM) biogenesis remain unknown. Thermotogae is an early-branching phylum with a unique OM, the toga. Here, we use cryo-electron tomography to characterize the in situ cell envelope architecture of Thermotoga maritima and show that the toga is made of extended sheaths of β-barrel trimers supporting small (~200 nm) membrane patches. Lipidomic analyses identified the same major lipid species in the inner membrane (IM) and toga, including the rare to bacteria membrane-spanning ether-bound diabolic acids (DAs). Proteomic analyses revealed that the toga was composed of multiple SLH-domain containing Ompα and novel β-barrel proteins, and homology searches detected variable conservations of these proteins across the phylum. These results highlight that, in contrast to the SlpA/OmpM superfamily of proteins, Thermotoga possess a highly diverse bipartite OM-tethering system. We discuss the implications of our findings with respect to other early-branching phyla and propose that a toga-like intermediate may have facilitated monoderm-to-diderm cell envelope transitions.
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Affiliation(s)
- Danielle L. Sexton
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver,V6T1Z3 BC, Canada
| | - Ameena Hashimi
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver,V6T1Z3 BC, Canada
| | - Polina Beskrovnaya
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver,V6T1Z3 BC, Canada
| | - Lloyd Sibanda
- Department of Chemistry, University of British Columbia, Vancouver,V6T1Z1 BC, Canada
| | - Tao Huan
- Department of Chemistry, University of British Columbia, Vancouver,V6T1Z1 BC, Canada
| | - Elitza I. Tocheva
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver,V6T1Z3 BC, Canada
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De la Cruz FB, Cheng Q, Call DF, Barlaz MA. Evidence of thermophilic waste decomposition at a landfill exhibiting elevated temperature regions. WASTE MANAGEMENT (NEW YORK, N.Y.) 2021; 124:26-35. [PMID: 33596536 DOI: 10.1016/j.wasman.2021.01.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/07/2021] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
There have been several reports of landfills exhibiting temperatures as high as 80 to 100 °C. This observation has motivated researchers to understand the causes of the elevated temperatures and to develop predictive models of landfill temperature. The objective of this research was to characterize the methanogenic activity of microbial communities that were derived from landfill samples excavated from a section of a landfill exhibiting gas well temperatures above 55 °C. Specific objectives were to: (1) determine the upper temperature limit for methane production; (2) evaluate the kinetics of methane generation when landfill-derived microcosms are incubated above and below their excavation temperature and derive a temperature inhibition function; and (3) evaluate microbial community shifts in response to temperature perturbations. Landfill microcosms were derived from 57 excavated landfill samples and incubated within ±2.5 °C of their excavation temperature between 42.5 °C and 87.5 °C. Results showed an optimum temperature for methane generation of ~57 °C and a 95% reduction in methane yield at ~72 °C. When select cultures were perturbed between 5 °C below and 15 °C above their in-situ temperature, both the rate and maximum methane production decreased as incubation temperature increased. Microbial community characterization using 16S rRNA amplicon sequencing suggests that thermophilic methanogenic activity can be attributed to methanogens of the genus Methanothermobacter. This study demonstrated that from a microbiological standpoint, landfills may maintain active methanogenic processes while experiencing temperatures in the thermophilic regime (<72 °C).
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Affiliation(s)
- Florentino B De la Cruz
- Department of Civil, Construction, and Environmental Engineering, Campus Box 7908, North Carolina State University, Raleigh, NC 27695-7908, United States.
| | - Qiwen Cheng
- Department of Civil, Construction, and Environmental Engineering, Campus Box 7908, North Carolina State University, Raleigh, NC 27695-7908, United States
| | - Douglas F Call
- Department of Civil, Construction, and Environmental Engineering, Campus Box 7908, North Carolina State University, Raleigh, NC 27695-7908, United States
| | - Morton A Barlaz
- Department of Civil, Construction, and Environmental Engineering, Campus Box 7908, North Carolina State University, Raleigh, NC 27695-7908, United States
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Wang Q, Sha C, Wang H, Ma K, Wiegle J, Abomohra AEF, Shao W. A novel bifunctional aldehyde/alcohol dehydrogenase catalyzing reduction of acetyl-CoA to ethanol at temperatures up to 95 °C. Sci Rep 2021; 11:1050. [PMID: 33441766 PMCID: PMC7806712 DOI: 10.1038/s41598-020-80159-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 12/16/2020] [Indexed: 11/09/2022] Open
Abstract
Hyperthermophilic Thermotoga spp. are excellent candidates for the biosynthesis of cellulosic ethanol producing strains because they can grow optimally at 80 °C with ability to degrade and utilize cellulosic biomass. In T. neapolitana (Tne), a putative iron-containing alcohol dehydrogenase was, for the first time, revealed to be a bifunctional aldehyde/alcohol dehydrogenase (Fe-AAdh) that catalyzed both reactions from acetyl-coenzyme A (ac-CoA) to acetaldehyde (ac-ald), and from ac-ald to ethanol, while the putative aldehyde dehydrogenase (Aldh) exhibited only CoA-independent activity that oxidizes ac-ald to acetic acid. The biochemical properties of Fe-AAdh were characterized, and bioinformatics were analyzed. Fe-AAdh exhibited the highest activities for the reductions of ac-CoA and acetaldehyde at 80-85 °C, pH 7.54, and had a 1-h half-life at about 92 °C. The Fe-AAdh gene is highly conserved in Thermotoga spp., Pyrococcus furiosus and Thermococcus kodakarensis, indicating the existence of a fermentation pathway from ac-CoA to ethanol via acetaldehyde as the intermediate in hyperthermophiles.
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Affiliation(s)
- Qiang Wang
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Chong Sha
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Hongcheng Wang
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Kesen Ma
- Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - Juergen Wiegle
- Department of Microbiology, University of Georgia, Athens, GA, 30602, USA
| | - Abd El-Fatah Abomohra
- Department of Environmental Engineering, School of Architecture and Civil Engineering, Chengdu University, Chengdu, 610106, China. .,Botany Department, Faculty of Science, Tanta University, Tanta, 31527, Egypt.
| | - Weilan Shao
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China.
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Efficient xylan-to-sugar biotransformation using an engineered xylanase in hyperthermic environment. Int J Biol Macromol 2020; 157:17-23. [DOI: 10.1016/j.ijbiomac.2020.04.145] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/11/2020] [Accepted: 04/18/2020] [Indexed: 11/30/2022]
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Hao L, McIlroy SJ, Kirkegaard RH, Karst SM, Fernando WEY, Aslan H, Meyer RL, Albertsen M, Nielsen PH, Dueholm MS. Novel prosthecate bacteria from the candidate phylum Acetothermia. THE ISME JOURNAL 2018; 12:2225-2237. [PMID: 29884828 PMCID: PMC6092417 DOI: 10.1038/s41396-018-0187-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/09/2018] [Accepted: 03/20/2018] [Indexed: 02/05/2023]
Abstract
Members of the candidate phylum Acetothermia are globally distributed and detected in various habitats. However, little is known about their physiology and ecological importance. In this study, an operational taxonomic unit belonging to Acetothermia was detected at high abundance in four full-scale anaerobic digesters by 16S rRNA gene amplicon sequencing. The first closed genome from this phylum was obtained by differential coverage binning of metagenomes and scaffolding with long nanopore reads. Genome annotation and metabolic reconstruction suggested an anaerobic chemoheterotrophic lifestyle in which the bacterium obtains energy and carbon via fermentation of peptides, amino acids, and simple sugars to acetate, formate, and hydrogen. The morphology was unusual and composed of a central rod-shaped cell with bipolar prosthecae as revealed by fluorescence in situ hybridization combined with confocal laser scanning microscopy, Raman microspectroscopy, and atomic force microscopy. We hypothesize that these prosthecae allow for increased nutrient uptake by greatly expanding the cell surface area, providing a competitive advantage under nutrient-limited conditions.
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Affiliation(s)
- Liping Hao
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | - Simon Jon McIlroy
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | - Rasmus Hansen Kirkegaard
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | - Søren Michael Karst
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | | | - Hüsnü Aslan
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - Rikke Louise Meyer
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - Mads Albertsen
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark
| | - Per Halkjær Nielsen
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark.
| | - Morten Simonsen Dueholm
- Department of Chemistry and Bioscience, Center for Microbial Communities, Aalborg University, Aalborg, Denmark.
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Cibis KG, Gneipel A, König H. Isolation of acetic, propionic and butyric acid-forming bacteria from biogas plants. J Biotechnol 2016; 220:51-63. [PMID: 26779817 DOI: 10.1016/j.jbiotec.2016.01.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 01/07/2016] [Accepted: 01/12/2016] [Indexed: 11/16/2022]
Abstract
In this study, acetic, propionic and butyric acid-forming bacteria were isolated from thermophilic and mesophilic biogas plants (BGP) located in Germany. The fermenters were fed with maize silage and cattle or swine manure. Furthermore, pressurized laboratory fermenters digesting maize silage were sampled. Enrichment cultures for the isolation of acid-forming bacteria were grown in minimal medium supplemented with one of the following carbon sources: Na(+)-dl-lactate, succinate, ethanol, glycerol, glucose or a mixture of amino acids. These substrates could be converted by the isolates to acetic, propionic or butyric acid. In total, 49 isolates were obtained, which belonged to the phyla Firmicutes, Tenericutes or Thermotogae. According to 16S rRNA gene sequences, most isolates were related to Clostridium sporosphaeroides, Defluviitoga tunisiensis and Dendrosporobacter quercicolus. Acetic, propionic or butyric acid were produced in cultures of isolates affiliated to Bacillus thermoamylovorans, Clostridium aminovalericum, Clostridium cochlearium/Clostridium tetani, C. sporosphaeroides, D. quercicolus, Proteiniborus ethanoligenes, Selenomonas bovis and Tepidanaerobacter sp. Isolates related to Thermoanaerobacterium thermosaccharolyticum produced acetic, butyric and lactic acid, and isolates related to D. tunisiensis formed acetic acid. Specific primer sets targeting 16S rRNA gene sequences were designed and used for real-time quantitative PCR (qPCR). The isolates were physiologically characterized and their role in BGP discussed.
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Affiliation(s)
- Katharina Gabriela Cibis
- Institute of Microbiology and Wine Research (IMW), Johannes Gutenberg-Universität of Mainz, Johann-Joachim-Becherweg 15, 55128 Mainz, Germany.
| | - Armin Gneipel
- Institute of Microbiology and Wine Research (IMW), Johannes Gutenberg-Universität of Mainz, Johann-Joachim-Becherweg 15, 55128 Mainz, Germany
| | - Helmut König
- Institute of Microbiology and Wine Research (IMW), Johannes Gutenberg-Universität of Mainz, Johann-Joachim-Becherweg 15, 55128 Mainz, Germany
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A thermostable S-adenosylhomocysteine hydrolase from Thermotoga maritima: properties and its application on S-adenosylhomocysteine production with enzymatic cofactor regeneration. Enzyme Microb Technol 2014; 64-65:33-7. [PMID: 25152414 DOI: 10.1016/j.enzmictec.2014.06.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 06/27/2014] [Accepted: 06/30/2014] [Indexed: 11/20/2022]
Abstract
S-adenosylhomocysteine (SAH) is an effective sedative, a good sleep modulator, and a new anticonvulsant. SAH can be synthesized from adenosine and homocysteine by using microbial S-adenosylhomocysteine hydrolase (SAHase). The extremely thermostable SAHase and lactate dehydrogenase (LDH) from Thermotoga maritima were successfully overexpressed in Escherichia coli, and purified by heat treatments. The SAHase exhibited the highest activity at 85 °C and pH 8.0 with a specific activity of 6.2 U/mg when NAD concentration was 1mM. However, optimal SAHase reaction conditions shifted to 100 °C and pH 11.2, and its specific activity increased to 36.8 U/mg after NAD concentration was raised to 8mM. Biosynthesis of SAH at 85 °C largely increased the adenosine solubility which was a limiting factor for improving the titer of product. At 85 °C and pH 8.0, 24 μmol of SAH was obtained when 0.5mg of SAHase was applied to a 10 ml reaction mixture. The SAH production was further increased to 153 μmol by adding LDH and pyruvate into the reaction mixture for NAD regeneration. Therefore, extremely thermostable enzymes SAHase and LDH from T. maritima form an efficient NAD consumption and regeneration system for SAH biosynthesis. This method has great potential for industrial-scale enzymatic production of SAH.
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Le Y, Chen H, Zagursky R, Wu JHD, Shao W. Thermostable DNA ligase-mediated PCR production of circular plasmid (PPCP) and its application in directed evolution via in situ error-prone PCR. DNA Res 2013; 20:375-82. [PMID: 23633530 PMCID: PMC3738163 DOI: 10.1093/dnares/dst016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Polymerase chain reaction (PCR) is a powerful method to produce linear DNA fragments. Here we describe the Tma thermostable DNA ligase-mediated PCR production of circular plasmid (PPCP) and its application in directed evolution via in situ error-prone PCR. In this thermostable DNA ligase-mediated whole-plasmid amplification method, the resultant DNA nick between the 5′ end of the PCR primer and the extended newly synthesized DNA 3′ end of each PCR cycle is ligated by Tma DNA ligase, resulting in circular plasmid DNA product that can be directly transformed. The template plasmid DNA is eliminated by ‘selection marker swapping’ upon transformation. When performed under an error-prone condition with Taq DNA polymerase, PPCP allows one-step construction of mutagenesis libraries based on in situ error-prone PCR so that random mutations are introduced into the target gene without altering the expression vector plasmid. A significant difference between PPCP and previously published methods is that PPCP allows exponential amplification of circular DNA. We used this method to create random mutagenesis libraries of a xylanase gene and two cellulase genes. Screening of these libraries resulted in mutant proteins with desired properties, demonstrating the usefulness of in situ error-prone PPCP for creating random mutagenesis libraries for directed evolution.
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Affiliation(s)
- Yilin Le
- Biofuels Institute, School of Environment, Jiangsu University, Zhenjiang, Jiangsu 212013, PR China
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The temperature dependent proteomic analysis of Thermotoga maritima. PLoS One 2012; 7:e46463. [PMID: 23071576 PMCID: PMC3465335 DOI: 10.1371/journal.pone.0046463] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 08/30/2012] [Indexed: 11/21/2022] Open
Abstract
Thermotoga maritima (T. maritima) is a typical thermophile, and its proteome response to environmental temperature changes has yet to be explored. This study aims to uncover the temperature-dependent proteins of T. maritima using comparative proteomic approach. T. maritima was cultured under four temperatures, 60°C, 70°C, 80°C and 90°C, and the bacterial proteins were extracted and electrophoresed in two-dimensional mode. After analysis of gel images, a total of 224 spots, either cytoplasm or membrane, were defined as temperature-dependent. Of these spots, 75 unique bacterial proteins were identified using MALDI TOF/TOF MS. As is well known, the chaperone proteins such as heat shock protein 60 and elongation factor Tu, were up-regulated in abundance due to increased temperature. However, several temperature-dependent proteins of T. maritima responded very differently when compared to responses of the thermophile T. tengcongensis. Intriguingly, a number of proteins involved in central carbohydrate metabolism were significantly up-regulated at higher temperature. Their corresponding mRNA levels were elevated accordingly. The increase in abundance of several key enzymes indicates that a number of central carbohydrate metabolism pathways of T. maritima are activated at higher temperatures.
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Han D, Norris SM, Xu Z. Construction and transformation of a Thermotoga-E. coli shuttle vector. BMC Biotechnol 2012; 12:2. [PMID: 22225774 PMCID: PMC3398313 DOI: 10.1186/1472-6750-12-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 01/06/2012] [Indexed: 11/29/2022] Open
Abstract
Background Thermotoga spp. are attractive candidates for producing biohydrogen, green chemicals, and thermostable enzymes. They may also serve as model systems for understanding life sustainability under hyperthermophilic conditions. A lack of genetic tools has hampered the investigation and application of these organisms. This study aims to develop a genetic transfer system for Thermotoga spp. Results Methods for preparing and handling Thermotoga solid cultures under aerobic conditions were optimized. A plating efficiency of ~50% was achieved when the bacterial cells were embedded in 0.3% Gelrite. A Thermotoga-E. coli shuttle vector pDH10 was constructed using pRQ7, a cryptic mini-plasmid found in T. sp. RQ7. Plasmid pDH10 was introduced to T. maritima and T. sp. RQ7 by electroporation and liposome-mediated transformation. Transformants were isolated, and the transformed kanamycin resistance gene (kan) was detected from the plasmid DNA extracts of the recombinant strains by PCR and was confirmed by restriction digestions. The transformed DNA was stably maintained in both Thermotoga and E. coli even without the selective pressure. Conclusions Thermotoga are transformable by multiple means. Recombinant Thermotoga strains have been isolated for the first time. A heterologous kan gene is functionally expressed and stably maintained in Thermotoga.
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Affiliation(s)
- Dongmei Han
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA
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Properties of recombinant Strep-tagged and untagged hyperthermophilic D-arabitol dehydrogenase from Thermotoga maritima. Appl Microbiol Biotechnol 2011; 90:1285-93. [PMID: 21347726 DOI: 10.1007/s00253-011-3187-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 02/14/2011] [Accepted: 02/14/2011] [Indexed: 10/18/2022]
Abstract
The first hyperthermophilic D-arabitol dehydrogenase from Thermotoga maritima was heterologously purified from Escherichia coli. The protein was purified with and without a Strep-tag. The enzyme exclusively catalyzed the NAD(H)-dependent oxidoreduction of D-arabitol, D-xylitol, D-ribulose, or D-xylulose. A twofold increase of catalytic rates was observed upon addition of Mg(2+) or K(+). Interestingly, only the tag-less protein was thermostable, retaining 90% of its activity after 90 min at 85 °C. However, the tag-less form of D-arabitol dehydrogenase had similar kinetic parameters compared to the tagged enzyme, demonstrating that the Strep-tag was not deleterious to protein function but decreased protein stability. A single band at 27.6 kDa was observed on SDS-PAGE and native PAGE revealed that the protein formed a homohexamer and a homododecamer. The enzyme catalyzed oxidation of D-arabitol to D: -ribulose and therefore belongs to the class of D-arabitol 2-dehydrogenases, which are typically observed in yeast and not bacteria. The product D-ribulose is a rare ketopentose sugar that has numerous industrially applications. Given its thermostability and specificity, D-arabitol 2-dehydrogenase is a desirable biocatalyst for the production of rare sugar precursors.
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Properties of an NAD+-dependent DNA ligase from the hyperthermophile Thermotoga maritima and its application in PCR amplification of long DNA fragments. Enzyme Microb Technol 2010. [DOI: 10.1016/j.enzmictec.2009.08.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Nguyen TAD, Han SJ, Kim JP, Kim MS, Sim SJ. Hydrogen production of the hyperthermophilic eubacterium, Thermotoga neapolitana under N2 sparging condition. BIORESOURCE TECHNOLOGY 2010; 101 Suppl 1:S38-S41. [PMID: 19361983 DOI: 10.1016/j.biortech.2009.03.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 02/15/2009] [Accepted: 03/12/2009] [Indexed: 05/27/2023]
Abstract
Gas sparging was found to be a useful technique to reduce hydrogen partial pressure in the liquid phase to enhance the hydrogen yields of strictly anaerobically fermentative bacteria. The effect of nitrogen (N(2)) sparging on hydrogen yield was investigated in sterile and non-sterile conditions using a pure strain of the hyperthermophilic eubacteria, Thermotoga neapolitana with glucose or xylose as a carbon source. The maximum hydrogen accumulations reached 41% of the gaseous mixtures after 30-40 h. Two applications of N(2) sparging after the H(2) content in the headspace reached the maximum levels gave an increase of H(2) production by 78% from 1.82 to 3.24 mol H(2)/mol glucose and by 56% from 1.41 to 2.20 mol H(2)/mol xylose. This result suggested that the removal of the produced H(2) from the gas headspace of the limited-volume, closed culture vial when it achieves the maximum level of H(2) tolerance of the bacterium is a necessary technique to improve its H(2) yield.
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Affiliation(s)
- Tam-Anh D Nguyen
- Department of Chemical Engineering, Sungkyunkwan University, Suwon, South Korea
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Yang X, Ma K. Characterization of an exceedingly active NADH oxidase from the anaerobic hyperthermophilic bacterium Thermotoga maritima. J Bacteriol 2007; 189:3312-7. [PMID: 17293421 PMCID: PMC1855830 DOI: 10.1128/jb.01525-06] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An NADH oxidase from the anaerobic hyperthermophilic bacterium Thermotoga maritima was purified. The enzyme was very active in catalyzing the reduction of oxygen to hydrogen peroxide with an optimal pH value of 7 at 80 degrees C. The V(max) was 230 +/- 14 mumol/min/mg (k(cat)/K(m) = 548,000 min(-1) mM(-1)), and the K(m) values for NADH and oxygen were 42 +/- 3 and 43 +/- 4 muM, respectively. The NADH oxidase was a heterodimeric flavoprotein with two subunits with molecular masses of 54 kDa and 46 kDa. Its gene sequences were identified, and the enzyme might represent a new type of NADH oxidase in anaerobes. An NADH-dependent peroxidase with a specific activity of 0.1 U/mg was also present in the cell extract of T. maritima.
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Affiliation(s)
- Xianqin Yang
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
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