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

Abstract

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.

Seasonal Dynamics of Anammox Bacteria in Estuarial Sediment of the Mai Po Nature Reserve Revealed by Analyzing the 16S rRNA and Hydrazine Oxidoreductase (hzo) Genes

“…In addition, its significant positive relationship with bacterial community and abundance further indicates that temperature is an important environmental factor influencing the seasonal variation of anammox bacteria in Mai Po. Previous studies have found that 'Scalindua' anammox bacteria are distributed in low-temperature environments in sea water columns, surface and subsurface of ocean sediment (8,14,49), while quite different in high-temperature environments, such as hydrothermal vents (3) and oil reservoirs (22), indicating 'Scalindua' species prefer low-temperature environments. Our results are consistent with these findings, with 'Scalindua' bacteria dominating in winter.…”

“…The anammox process has been demonstrated in marine ecosystems (15,19,20,31,43,45,47) and freshwater terrestrial ecosystems (29,41), low-temperature polar regions (32,33) and high-temperature hot spring and deep sea hydrothermal vents (3,13), and oil reservoirs (22), even on the surface of marine sponges (12,26). Certain Planctomycetes are monophyletic members linked to this process, and five genera, 'Candidatus Brocadia', 'Candidatus Kuenenia', 'Candidatus Anammoxoglobus', 'Candidatus Scalindua' and 'Candidatus Jettenia', have been described (16-18, 30, 37).…”

“…Functional biomarkers that respond to the anammox process are needed to describe anammox bacterial ecology more comprehensively. Hydrazine oxidoreductase (HZO) dehydrogenated the unique anammox intermediate, hydrazine, to form dinitrogen gas, and has been proposed as a functional biomarker for anammox bacteria, especially the two copies of the HZO-encoding gene (hzo) within hzo-cluster 1 (34,40), and recent studies also successfully used hzo to evaluate the diversity and distribution of anammox bacteria in different natural ecosystems, including marine sediment (23), a wastewater treatment plant (24) and high-temperature petroleum reservoirs (22). On the other hand, knowledge about the temporal community structure of anammox bacteria in natural ecosystems is still limited, especially in natural ecosystems with anthropogenic influences.…”

Geomicrobial functional groups: A window on the interaction between life and environments

“…In addition to denitrification, anammox, a process that converts ammonium and nitrite into nitrogen gas [74], may contribute 30%-50% of the nitrogen loss. The anammox bacteria, phylogenetically falling into Planctomycetes, are characterized by slow growth, but a diverse occurrence in anoxic marine or lacustrine environments or even high-temperature petroleum reservoirs [75,76]. In-depth investigations of anammox bacteria will re-shape our understanding of the nitrogen cycle throughout Earth history.…”

Anammox bacteria detected in fish intestinal tract systems

“…Anammox bacteria have been identified in highly diverse ecosystems including marine sediments [7] , rice paddy fields [8] , coastal wetlands [9] , fresh water terrestrial ecosystems [10][11][12] , oil fields [13] , and wastewater sludges [5] . Out of the 5 genera of anammox bacteria, Ca.…”