Petrotoga mexicana sp. nov., a novel thermophilic, anaerobic and xylanolytic bacterium isolated from an oil-producing well in the Gulf of Mexico

Abstract

A novel anaerobic, thermophilic, xylanolytic, motile rod-shaped bacterium with a sheath-like outer structure (toga) was isolated from a Mexican oil well in the Gulf of Mexico. Strain MET12 T was a Gram-negative bacterium, reducing elemental sulfur, thiosulfate and sulfite to hydrogen sulfide. Its optimum growth conditions were 55 6C, pH 6?6, 3 % NaCl and 0?15 % MgCl 2 .6H 2 O. The DNA G+C content was 36?1 mol%. Phylogenetically, strain MET12T was related to members of genus Petrotoga, with similarities to Petrotoga mobilis, Petrotoga sibirica, Petrotoga miotherma and Petrotoga olearia varying from 97?6 to 98?8 %. However DNA-DNA relatedness values between these species and strain MET12 T were lower than 70 %. As strain MET12 T (=DSM 14811 T =CIP 107371 T ) was genomically and phenotypically different from existing Petrotoga species, it is proposed as the type strain of a novel species, Petrotoga mexicana sp. nov.Anaerobes have always been considered as the dominant micro-organisms of petroleum reservoirs (Magot et al., 2000). Among them, fermentative bacteria constitute an important microbial community of the oilfield environment. Thermophilic isolates are the most studied, probably because (i) most oil reservoirs occur at depths where the temperature is high and (ii) thermophiles possess thermostable enzymes of great interest in industrial processes. Stetter et al. (1993) provided evidence of the presence of Thermotoga strains, members of the order Thermotogales, in oilfields. The isolation of Thermotoga elfii, Thermotoga subterranea and Thermotoga hypogea from such ecosystems was reported shortly afterwards (Fardeau et al., 1997a;Jeanthon et al., 1995;Ravot et al., 1995a). Microbial studies on various hot oil reservoirs throughout the world have provided evidence of the importance of micro-organisms morphologically and physiologically close to other members of Thermotogales, namely Fervidobacterium, Thermosipho, Geotoga and Petrotoga (Grassia et al., 1996;Magot et al., 2000). However, no Fervidobacterium species originating from oilfield reservoirs has been characterized so far. Davey et al. (1993) first reported the presence of microorganisms belonging to the genera Geotoga and Petrotoga in petroleum reservoirs located in Oklahoma and Texas.Three novel species were fully characterized: Geotoga petraea, Geotoga subterranea and Petrotoga miotherma. Later, Petrotoga mobilis was isolated from a North Sea oilproduction well (Lien et al., 1998). Petrotoga olearia and Petrotoga sibirica were recently isolated from a continental petroleum reservoir in Western Siberia (L'Haridon et al., 2002), from which L' Haridon et al. (2001) also isolated a novel species of the genus Thermosipho. Members of the genus Petrotoga are thermophilic heterotrophs that grow in a broad range of salt concentrations (up to 10 % NaCl). During our microbial studies of oil waters originating from offshore reservoirs located in the Gulf of Mexico, we isolated a novel thermophilic strain phylogenetically related to the genus Petrotoga, which we...

Biogeochemical Reduction Processes in a Hyper-Alkaline Leachate Affected Soil Profile

“…Typically Petrotoga species are strictly anaerobic fermentative bacteria that can oxidise sugars and some polymers during energy metabolism to produce lactate, acetate, CO 2 and H 2 as metabolites (Lien et al 1998;L'Haridon et al 2002;Miranda-Tello et al 2004;Miranda-Tello et al 2007). Most members of this phylum that have been isolated to date are tough thermophiles recovered from deep oil reservoirs, and have adapted to this harsh environment with a sheath-like outer structure that helps them resist environmental stress (Miranda-Tello et al 2004). Recently similar gene sequences have been detected in mesophilic anaerobic environments under stress from toxic chemicals (Nesbo et al 2006), suggesting that adaptations to survive at high temperatures may also provide resistance to chemical stress.…”

Defluviitoga tunisiensis gen. nov., sp. nov., a thermophilic bacterium isolated from a mesothermic and anaerobic whey digester

“…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.…”

“…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.…”

Desulfotomaculum hydrothermale sp. nov., a thermophilic sulfate-reducing bacterium isolated from a terrestrial Tunisian hot spring

“…Phase-contrast microscopy (Eclipse E600; Nikon) was used for routine examination of the cultures and to obtain photomicrographs. Light and electron microscopy were performed as described previously (Miranda-Tello et al, 2004). Growth was measured by inserting tubes directly into a model Cary 50 Scan spectrophotometer (Varian) and measuring the OD 580 .…”