Molecular Detection of Anaerobic Ammonium-Oxidizing (Anammox) Bacteria in High-Temperature Petroleum Reservoirs

Anaerobic ammonium-oxidizing (anammox) process plays an important role in the nitrogen cycle of the worldwide anoxic and mesophilic habitats. Recently, the existence and activity of anammox bacteria have been detected in some thermophilic environments, but their existence in the geothermal subterranean oil reservoirs is still not reported. This study investigated the abundance, distribution and functional diversity of anammox bacteria in nine out of 17 high-temperature oil reservoirs by molecular ecology analysis. High concentration (5.31–39.2 mg l−1) of ammonium was detected in the production water from these oilfields with temperatures between 55°C and 75°C. Both 16S rRNA and hzo molecular biomarkers indicated the occurrence of anammox bacteria in nine out of 17 samples. Most of 16S rRNA gene phylotypes are closely related to the known anammox bacterial genera Candidatus Brocadia, Candidatus Kuenenia, Candidatus Scalindua, and Candidatus Jettenia, while hzo gene phylotypes are closely related to the genera Candidatus Anammoxoglobus, Candidatus Kuenenia, Candidatus Scalindua, and Candidatus Jettenia. The total bacterial and anammox bacterial densities were 6.4 ± 0.5 × 103 to 2.0 ± 0.18 × 106 cells ml−1 and 6.6 ± 0.51 × 102 to 4.9 ± 0.36 × 104 cell ml−1, respectively. The cluster I of 16S rRNA gene sequences showed distant identity (<92%) to the known Candidatus Scalindua species, inferring this cluster of anammox bacteria to be a new species, and a tentative name Candidatus “Scalindua sinooilfield” was proposed. The results extended the existence of anammox bacteria to the high-temperature oil reservoirs

Caminibacter profundus sp nov., a novel thermophile of Nautiliales ord. nov within the class `Epsilonproteobacteria', isolated from a deep-sea hydrothermal vent

A novel moderately thermophilic, microaerobic to anaerobic, chemolithoautotrophic bacterium, designated strain CRT, was isolated from a deep-sea hydrothermal vent site at 36degreesN on the Mid-Atlantic Ridge. Cells were Gram-negative, non-motile rods. The organism grew at 45-65 degreesC and pH 6.5-7.4,with optimum growth at 55 degreesC and pH 6.9-7.1. The NaCl range for growth was 5-50 g l(-1) (optimum 30 g l(-1)). Strain CRT was an obligate chemolithoautotroph, growing with H-2 as energy source, sulfur, nitrate or oxygen as electron acceptors and CO2 as carbon source. Hydrogen sulfide and ammonium were the respective products of sulfur and nitrate reduction. The G+C; content of the genomic DNA was 32.1 mol%. Based on 16S rRNA gene sequence analysis, this organism was most closely related to Caminibacter hydrogeniphilus (94.9% similarity). On the basis of phenotypic and phylogenetic data, it is proposed that the isolate represents a novel species, Caminibacter profundus sp. nov. The type strain is CRT (= DSM 15016(T)= JCM 11957(T)). The phylogenetic data also correlate well with the significant phenotypic differences between the lineage encompassing the genera Nautilia and Caminibacter and other members of the class `Epsilonproteobacteria'. The lineage encompassing the genera Nautilia and Caminibacter is therefore proposed as a new order, Nautiliales ord. nov., represented by a single family, Nautiliaceae fam. nov

Petrotoga olearia sp nov and Petrotoga sibirica sp nov., two thermophilic bacteria isolated from a continental petroleum reservoir in Western Siberia

Strictly anaerobic, thermophilic bacteria (strains SL24(T), SL25(T), SL27, SL29 and SL32) were isolated from a deep, continental oil reservoir in Western Siberia (Russia). These motile, rod-shaped organisms were surrounded by a sheath-like structure, a feature characteristic of the Thermotogales. On the basis of partial 16S rDNA sequences (500 nucleotides), strains SL25(T), SL27, SL29 and SL32 were identical. Therefore, only strains SL24(T) and SL25(T) were studied in detail. The optimum temperature for growth of both strains was 55degreesC. Their optimum pH for growth was 7.5 and their optimum NaCl concentration was between 20 and 30 g l(-1). The novel isolates reduced elemental sulfur and cystine, but not thiosulfate or sulfate, to hydrogen sulfide. The G+C contents of the genomic DNA of strains SL24(T) and SL25(T) were respectively 35 and 33 mol%. Phylogenetically, both strains are most closely related to Petrotoga miotherma, there being 98.9-99.4% similarity between their 16S rDNA sequences. Phenotypic properties and DNA-DNA hybridization experiments indicate that the strains belong to two novel species, for which the names Petrotoga olearia (type strain SL24(T)=DSM 13574(T)=JCM 11234(T)) and Petrotoga sibirica (type strain SL25(T)=DSM 13575(T)=JCM 11235(T)) are proposed

Nautilia lithotrophica gen. nov., sp nov., a thermophilic sulfur-reducing epsilon-proteobacterium isolated from a deep-sea hydrothermal vent

A novel, strictly anaerobic, thermophilic sulfur-reducing bacterium, strain 525(T), was isolated from tubes of the deep-sea hydrothermal vent polychaete Alvinella pompejana, collected on the East Pacific Rise (13degrees N). This organism grew in the temperature range 37-68 degreesC, the optimum being 53 degreesC, and in the pH range 6.4-7.4, the optimum being 6.8-7.0. The NaCl range for growth was 0.8-5.0%, the optimum being 3.0%. Strain 525(T) grew lithoautotrophically with H-2 as energy source, S-o as electron acceptor and CO2 as carbon source. Alternatively, strain 525(T) was able to use formate as an energy source. The G+C content of the genomic DNA was 34.7 mol %. Phylogenetic analysis of the 16S rDNA gene sequence placed strain 525(T) in the c-subclass of the Proteobacteria, where it forms a deep cluster with recently isolated relatives. On the basis of phenotypic and phylogenetic differences between strain 525(T) and its closest phylogenetic relatives, it is proposed that the new isolate should be described as a member of a new genus, Nautilia, for which the name Nautilia lithotrophica gen. nov., sp. nov. is proposed. The type strain is strain 525(T) (= DSM 13520(T))

Deferribacter abyssi sp nov., an anaerobic thermophile from deep-sea hydrothermal vents of the Mid-Atlantic Ridge

Two strains of thermophilic, anaerobic, chemolithoautotrophic bacteria, designated JR(T) and DR, were isolated from hydrothermal samples collected on the Mid-Atlantic Ridge from the Rainbow (36degrees 16' N, 33degrees 54' W) and Menez Gwen (37degrees 50' N, 31degrees 50' W) vent fields, respectively. Cells of both isolates were short, straight- to vibrio-shaped, motile rods with one polar flagellum, and were Gram-negative and non-sporulating. Strain JRT was characterized in detail. It was found to grow optimally at pH 6.5-6.7, at 60 degreesC and in the presence of 30 g NaCl l(-1). Strain JR(T) could use molecular hydrogen, acetate, succinate, pyruvate and proteinaceous compounds as electron donors, and elemental sulfur, nitrate or Fe(III) as electron acceptors. No fermentation of organic substrates occurred. The G + C content of the DNA of strain JRT was 30.8 mol%. Strain DR (= DSM 14927) possessed the same morphology and pH, temperature and salinity optima and ranges, and used the same electron acceptors as strain JR(T). On the basis of their 16S rDNA sequences (1517 nucleotides), strains JRT and DR were identical and distantly related to Deferribacter thermophilus and Deferribacter desulfuricans (95.3 and 95.2 % sequence similarity, respectively). Based on their phenotypic and phylogenetic characteristics, it is proposed that both strains are members of a new species of the genus Deferribacter, for which the name Deferribacter abyssi (type strain JRT = DSM 14873(T) = JCM 11955(T)) is proposed