Mobilome of hyperthermophilic archaea dwelling in deep-sea hydrothermal vents is poorly characterized. To gain insight into genetic diversity and dynamics of mobile genetic elements in these environments we have sequenced five new plasmids from different Thermococcus strains that have been isolated from geographically remote hydrothermal vents. The plasmids were ascribed to two subfamilies, pTN2-like and pEXT9a-like. Gene content and phylogenetic analyses illuminated a robust connection between pTN2-like plasmids and Pyrococcus abyssi virus 1 (PAV1), with roughly half of the viral genome being composed of genes that have homologues in plasmids. Unexpectedly, pEXT9a-like plasmids were found to be closely related to the previously sequenced plasmid pMETVU01 from Methanocaldococcus vulcanius M7. Our data suggests that the latter observation is most compatible with an unprecedented horizontal transfer of a pEXT9a-like plasmid from Thermococcales to Methanococcales. Gene content analysis revealed that thermococcal plasmids encode Hfq-like proteins and toxin-antitoxin (TA) systems of two different families, VapBC and RelBE. Notably, although abundant in archaeal genomes, to our knowledge, TA and hfq-like genes have not been previously found in archaeal plasmids or viruses. Finally, the plasmids described here might prove to be useful in developing new genetic tools for hyperthermophiles.
Defluviitoga tunisiensis gen. nov., sp. nov., a thermophilic bacterium isolated from a mesothermic and anaerobic whey digester T , a thermophilic, anaerobic and slightly halophilic, rod-shaped bacterium with a sheath-like outer structure (toga), was isolated from a whey digester in Tunisia. The strain's nonmotile cells measured 3-30¾1 mm and appeared singly, in pairs or as long chains. The novel strain reduced thiosulfate and elemental sulfur, but not sulfate or sulfite, into sulfide. It grew at 37-65 6C (optimum 55 6C), at pH 6.5-7.9 (optimum pH 6.9) and with 0.2-3 % (w/v) NaCl (optimum 0.5 %). The G+C content of the strain's genomic DNA was 33.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SulfLac1T was most closely related to Petrotoga mobilis (91.4 % sequence similarity). Based on phenotypic, phylogenetic and chemotaxonomic evidence, strain SulfLac1 T represents a novel species of a new genus within the order Thermotogales, for which the name Defluviitoga tunisiensis gen. nov., sp. nov. is proposed. The type strain of the type species is SulfLac1The cultivated representatives of the order Thermotogales are thermophilic anaerobes that are known to thrive in geothermally heated environments (Huber & Hannig, 2006). Members of this order include, for example, species of the genera Thermotoga, Marinitoga, Thermosipho and Fervidobacterium that were isolated from hot locations on the seafloor (Huber et al., 1986(Huber et al., , 1989Urios et al., 2004) such as deep-sea hydrothermal chimneys (Antoine et al., 1997; Wery et al., 2001;Postec et al., 2005), from a hot inland oil well (Fardeau et al., 2009) or from a hot spring (Patel et al., 1985). The species belonging to the other genera in the order Thermotogales (i.e. Petrotoga, Geotoga, Kosmotoga, Thermococcoides and Oceanotoga) were all isolated from oilfield ecosystems (Davey et al., 1993;Miranda-Tello et al., 2004 DiPippo et al., 2009;Feng et al., 2010;Jayasinghearachchi & Lal, 2011). Curiously, some mesothermic ecosystems, such as anaerobic waste digesters and contaminated sediments, contain bacteria that have 16S rRNA gene sequences similar to those of thermophilic members of the order Thermotogales (van Houten et al., 2009;Briones et al., 2007; Chouari et al., 2005). Whether such bacteria, called 'mesotoga', are truly mesophilic remains a matter of debate, however, as none of them has yet been cultivated (Nesbø et al., 2006(Nesbø et al., , 2010. The order Thermotogales comprises anaerobic, chemo-organotrophic, non-sporulating, rod-shaped bacteria that are characterized by a sheath-like outer structure known as a 'toga' (Huber et al., 1986;Miranda-Tello et al., 2004.The present study represents a taxonomic characterization of a novel thermophilic bacterium that was isolated from a mesothermic digester used to process whey. The bacterium was found to show phenotypic and phylogenetic traits that led to its assignment to a novel species of a novel genus within the order Thermotogales.Samples were collected from the sludge of...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.