34-758: Thermotoga is a genus of the phylum Thermotogota . Members of Thermotoga are hyperthermophilic bacteria whose cell is wrapped in a unique sheath-like outer membrane, called a "toga". The members of the phylum stain Gram-negative as they possess a thin peptidoglycan in between two lipid bilayers, albeit both peculiar. The peptidoglycan is unusual as the crosslink is not only meso-diaminopimelate as occurs in Pseudomonadota , but D-lysine. The species are anaerobes with varying degrees of oxygen tolerance. They are capable of reducing elemental sulphur (S 0 ) to hydrogen sulphide. Whether thermophily
68-458: A phylum of the domain Bacteria . The phylum contains a single class, Thermotogae . The phylum Thermotogota is composed of Gram-negative staining, anaerobic , and mostly thermophilic and hyperthermophilic bacteria. The name of this phylum is derived from the existence of many of these organisms at high temperatures along with the characteristic sheath structure, or "toga", surrounding
102-495: A 10-kb gene deletion has been developed using the experimental microbial evolution in T. maritima . Thermotoga maritima has a great potential in hydrogen synthesis because it can ferment a wide variety of sugars and has been reported to produce the highest amount of H 2 (4 mol H 2 / mol glucose ). Due to lack of a genetic system for the past 30 years majority of the studies have been either focused on heterologous gene expression in E. coli or predicting models since
136-1532: A 70 °C deep continental oil reservoir in the East Paris Basin, France . The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) T. petrophila Takahata et al. 2001 T. maritima Huber et al. 1986 T. neapolitana Jannasch et al. 1989 P. thermarum (Windberger et al. 1992) Bhandari & Gupta 2014 (type sp.) [ Thermotoga thermarum ] " P. caldifontis " (Mori et al. 2014) Belahbib et al. 2018 [ Thermotoga caldifontis ] P. hypogea (Fardeau et al. 1997) Bhandari & Gupta 2014 [ Thermotoga hypogea ] " P. profunda " (Mori et al. 2014) Belahbib et al. 2018 [ Thermotoga profunda ] P. elfii (Ravot et al. 1995) Bhandari & Gupta 2014 [ Thermotoga elfii ] P. lettingae (Balk, Weijma & Stams 2002) Bhandari & Gupta 2014 [ Thermotoga lettingae ] P. subterranea (Jeanthon et al. 2000) Bhandari & Gupta 2014 [ Thermotoga subterranea ] Fervidobacteriaceae T. neapolitana T. maritima T. petrophila [incl. Thermotoga naphthophila Takahata et al. 2001 ] P. elfii " P. profunda " P. thermarum " P. caldifontis " P. hypogea Fervidobacteriaceae Thermotogota The Thermotogota are
170-494: A commercial scale. Overcoming this limit by improving the conversion of sugar to H 2 could lead to a superior H 2 producing biological system that may supersede fossil fuel-based H 2 production. Metabolic engineering in this bacterium led to development of strains of T. maritima that surpassed the Thauer limit of hydrogen production. One of the strains, also known as Tma200, produced 5.77 mol H 2 / mol glucose which
204-445: A gene knockout mutant of T. maritima remained unavailable. Developing a genetic system for T. maritima has been a challenging task primarily because of a lack of a suitable heat-stable selectable marker. Recently, the most reliable genetic system based on pyrimidine biosynthesis has been established in T. maritima . This newly developed genetic system relies upon a pyrE mutant that was isolated after cultivating T. maritima on
238-542: A non-essential consequence to thermophily and not the driver towards thermophily. The paper and the chapter in Bergey's manual were authored by several authors including the microbiologists Karl Stetter and Carl Woese . The Neo-Latin feminine name "thermotoga" means "the hot outer garment", being a combination of the Greek noun θέρμη ( therme , heat) or more correctly the adjective θερμός, ή, όν ( thermos, e, on , hot) and
272-433: A number of its subgroups. Many of these CSIs in important housekeeping proteins such as Pol1 , RecA , and TrpRS , and ribosomal proteins L4, L7/L12, S8, S9, etc. are uniquely present in different sequenced Thermotogota species providing novel molecular markers for this phylum. These studies also identified CSIs specific for each order and each family. These indels are the premise for the current taxonomic organization of
306-437: A possible biotechnological source for production of energy alternative to fossil fuels. Until recently, no biochemical or molecular markers were known that could distinguish the species from the phylum Thermotogota from all other bacteria. However, a recent comparative genomic study has identified large numbers of conserved signature indels (CSIs) in important proteins that are specific for either all Thermotogota species or
340-450: A pyrimidine biosynthesis inhibiting drug called 5-fluoroorotic acid (5-FOA). The pyrE mutant is an auxotrophic mutant for uracil . The pyrE from a distantly related genus of T. maritima rescued the uracil auxotrophy of the pyrE mutant of T. maritima and has been proven to be a suitable marker. For the first time, the use of this marker allowed the development of an arabinose ( araA ) mutant of T. maritima . This mutant explored
374-572: A single class (Thermotogae), four orders ( Thermotogales , Kosmotogales , Petrotogales , and Mesoaciditogales ) and five families (Thermatogaceae, Fervidobacteriaceae, Kosmotogaceae, Petrotogaceae, and Mesoaciditogaceae). It contains a total of 15 genera and 52 species. In the 16S rRNA trees, the Thermotogota have been observed to branch with the Aquificota (another phylum comprising hyperthermophilic organisms) in close proximity to
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#1732802210188408-453: Is also capable of metabolizing cellulose as well as xylan , yielding H 2 that could potentially be utilized as an alternative energy source to fossil fuels. Additionally, this species of bacteria is able to reduce Fe(III) to produce energy using anaerobic respiration. Various flavoproteins and iron-sulphur proteins have been identified as potential electron carriers for use during cellular respiration. However, when growing with sulfur as
442-408: Is an innovation of the lineage or an ancestral trait is unclear and cannot be determined. The genome of Thermotoga maritima was sequenced in 1999, revealing several genes of archaeal origin, possibly allowing its thermophilic adaptation. The CG (cytosine-guanine) content of T. maritima is 46.2%; most thermophiles in fact have high CG content; this has led to the speculation that CG content may be
476-509: Is capable of surviving in such extreme temperatures and conditions. The genome of T. maritima has been sequenced multiple times. Genome resequencing of T. maritima MSB8 genomovar DSM3109 determined that the earlier sequenced genome was an evolved laboratory variant of T. maritima with an approximately 8-kb deletion. Moreover, a variety of duplicated genes and direct repeats in its genome suggest their role in intra-molecular homologous recombination leading to genes deletion. A strain with
510-464: Is not as high as suggested in earlier studies. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) Thermotoga maritima Thermotoga maritima is a hyperthermophilic , anaerobic organism that is a member of the order Thermotogales . T. maritima is well known for its ability to produce hydrogen (clean energy) and it
544-499: Is potentially a very ancient organism. Thermotoga maritima is a non- sporulating , rod shaped, gram-negative bacterium. When viewed under a microscope , it can be seen to be encased in a sheath-like envelope which resembles a toga , hence the "toga" in its name. As an anaerobic fermentative chemoorganotrophic organism, T. maritima catabolizes sugars and polymers and produces carbon dioxide (CO 2 ) and hydrogen (H 2 ) gas as by-products of fermentation . T. maritima
578-399: Is present in a multi-copy (three copies) fashion. The gene disruptions of all three putative ATPase encoding subunit ( malK ) and phenotype have concluded that only one of the three copies serves as an ATPase function of the maltose transporter. It is interesting to know that T. maritima has several paralogs of many genes and the true function of these genes is now dependent upon the use of
612-581: Is the highest yield so far reported in a fermentative bacterium. In this strain, energy redistribution, and metabolic rerouting through the pentose phosphate pathway (PPP) generated excess reductants while uncoupling growth from hydrogen synthesis. Uncoupling of growth from product formation has been viewed as a viable strategy to maximize the product yield which has been achieved in the higher hydrogen producing bacterium. Similar strategies can be adopted for other hydrogen producing bacterium to maximize product yields. Hydrogenases are metalloenzymes that catalyze
646-509: Is the only fermentative bacterium that has been shown to produce hydrogen more than the Thauer limit (>4 mol H 2 /mol glucose). It employs [FeFe]-hydrogenases to produce hydrogen gas (H 2 ) by fermenting many different types of carbohydrates. First discovered in the sediment of a marine geothermal area near Vulcano , Italy, Thermotoga maritima resides in hot springs as well as hydrothermal vents . The ideal environment for
680-916: The CSI and a ADP/ATP molecule. It is thought that this network helps to maintain ADP/ATP binding to the SecA protein at high temperatures, contributing to the overall thermostable phenotype some Thermotogales species. Athalassotoga Mesoaciditoga Mesotoga Kosmotoga Marinitoga Tepiditoga Oceanotoga Geotoga Defluviitoga Petrotoga Thermotoga Pseudothermotoga Fervidobacterium Thermosipho Athalassotoga Mesoaciditoga Mesotoga Kosmotoga Marinitoga Tepiditoga Oceanotoga Geotoga Defluviitoga Petrotoga Thermotoga Pseudothermotoga Fervidobacterium Thermosipho This phylum presently consists of
714-645: The Latin feminine noun toga (the Roman outer garment). The precise relation of the Thermotogota to other phyla is debated ( v. bacterial phyla ): several studies have found it to be deep-branching (in Bergey's manual it appeared in fact in "Volume I: The Archaea and the deeply branching and phototrophic Bacteria"), while other have found Firmicutes to be deep-branching with Thermotogota clustering away from
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#1732802210188748-472: The Thermotogota, and are strongly supported by phylogenomic analyses. Additional CSIs have also been found that are specific for Thermotoga , Pseudothermotoga , Fervidobacterium , and Thermosipho . These CSIs are specific for all species within each respective genus, and absent in all other bacteria, thus are specific markers. A clade consisting of the deep-branching species Petrotoga mobilis , Kosmotoga olearia , and Thermotogales bacterium mesG1
782-670: The archaeal-bacterial branch point. However, a close relationship of the Thermotogota to the Aquificota, and the deep branching of the latter group of species, is not supported by phylogenetic studies based upon other gene/protein sequences. and also by conserved signature indels in several highly conserved universal proteins. The Thermotogota have also been scrutinized for their supposedly profuse Lateral gene transfer with Archaeal organisms. However, recent studies based upon more robust methodologies suggest that incidence of LGT between Thermotogota and other groups including Archaea
816-454: The base. The type species of the genus is T. maritima , first described in 1986. At the time, it was the first species of the phylum to be described. The genus Thermotoga now contains three official species. Recently eight species were transferred out of the genus and most of them ended up within the genus Pseudothermotoga by Bhandari & Gupta 2014. T. subterranea strain SL1 was found in
850-602: The best energy carrier due to its higher energy content per unit weight. T. maritima is one of fermentative bacteria that produces hydrogen to levels that approach the thermodynamic limit (4 mol H 2 / mol glucose). However, similar to other fermentative bacteria, the biohydrogen yield in this bacterium does not go beyond 4 mol H 2 / glucose (Thaeur limit) because of its inherent nature to use more energy for its own cell division to grow rapidly than producing H 2 . Because of these reasons fermentative bacteria have not been thought to produce higher amounts of hydrogen at
884-576: The cells of these species. Recently, some Thermotogota existing at moderate temperatures have also been identified. Although Thermotogota species exhibit Gram-negative staining, they are bounded by a single-unit lipid membrane, hence they are monoderm bacteria. Because of the ability of some Thermotogota species to thrive at high temperatures, they are considered attractive targets for use in industrial processes. The metabolic ability of Thermotogota to utilize different complex-carbohydrates for production of hydrogen gas led to these species being cited as
918-453: The final electron acceptor, no ATP is produced. Instead, this process eliminates inhibitory H 2 produced from fermentative growth. Collectively, these attributes indicate that T. maritima has become resourceful and capable of metabolizing a host of substances in order to carry out its life processes. Energy is a growing need of the world and it is expected to grow in the next 20 years. Among various energy sources, hydrogen serves as
952-484: The organism is a water temperature of 80 °C (176 °F), though it is capable of growing in waters of 55–90 °C (131–194 °F). Thermotoga maritima is the only bacterium known to grow at this high a temperature; the only other organisms known to live in environments this extreme are members of the domain Archaea . The hyperthermophilic abilities of T. maritima , along with its deep lineage, suggests that it
986-636: The presence of a Per-Arnt-Sim (PAS) domain . The genome of T. maritima consists of a single circular 1.8 megabase chromosome encoding for 1877 proteins. Within its genome it has several heat and cold shock proteins that are most likely involved in metabolic regulation and response to environmental temperature changes. It shares 24% of its genome with members of the Archaea; the highest percentage overlap of any bacteria. This similarity suggests horizontal gene transfer between Archaea and ancestors of T. maritima and could help to explain why T. maritima
1020-502: The presence of the same CSI within these two unrelated groups of bacteria is not due to lateral gene transfer , rather the CSI likely developed independently in these two groups of thermophiles due to selective pressure . The insert is located on the surface of the protein in the ATPase domain, near the binding site of ADP/ATP. Molecular dynamic stimulations revealed a network of hydrogen bonds formed between water molecules, residues within
1054-585: The recently developed system. The newly developed genetic system in T. maritima has a great potential to make T. maritima as a host for hyperthermophilic bacterial gene expression studies. Protein expression in this model organism is promising to synthesize fully functional protein without any treatment. Thermotoga maritima contains homologues of several competence genes, suggesting that it has an inherent system of internalizing exogenous genetic material, possibly facilitating genetic exchange between this bacterium and free DNA. Based on phylogenetic analysis of
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1088-428: The reversible hydrogen conversion reaction: H 2 ⇄ 2 H + 2 e . A Group C [FeFe]-hydrogenase from Thermotoga maritima ( Tm HydS) has showed modest hydrogen conversion activity and reduced sensitivity to the enzyme's inhibitor, CO, in comparison to Group A prototypical and bifurcating [FeFe]-hydrogenases. The Tm HydS has a hydrogenase domain with distinct amino acid modifications in the active site pocket, including
1122-481: The role of the pentose phosphate pathway of T. maritima in hydrogen synthesis. The genome of T. maritima possesses direct repeats that have developed into paralogs . Due to lack of a genetic system the true function of these paralogs has remained unknown. Recently developed genetic system in T. maritima has been very useful to determine the function of the ATPase protein (MalK) of the maltose transporter that
1156-561: Was also supported by seven CSIs. Additionally, some CSIs that provided evidence of LGT among the Thermotogota and other prokaryotic groups were also reported. The newly discovered molecular markers provide novel means for identification and circumscription of species from the phylum in molecular terms and for future revisions to its taxonomy. Additionally, a 51 aa insertion CSI was identified to be specific for all Thermotogales as well as Aquificales , another order comprising hyperthermophilic species. Phylogenetic studies demonstrated that
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