Abstract
To get a better knowledge on how archaeal communities differ between the oil and aqueous phases and whether environmental factors promote substantial differences on microbial distributions among production wells, we analyzed archaeal communities in oil and aqueous phases from four high-temperature petroleum reservoirs (55–65°C) by using 16S rRNA gene based 454 pyrosequencing. Obvious dissimilarity of the archaeal composition between aqueous and oil phases in each independent production wells was observed, especially in production wells with higher water cut, and diversity in the oil phase was much higher than that in the corresponding aqueous phase. Statistical analysis further showed that archaeal communities in oil phases from different petroleum reservoirs tended to be more similar, but those in aqueous phases were the opposite. In the high-temperature ecosystems, temperature as an environmental factor could have significantly affected archaeal distribution, and archaeal diversity raised with the increase of temperature (p < 0.05). Our results suggest that to get a comprehensive understanding of petroleum reservoirs microbial information both in aqueous and oil phases should be taken into consideration. The microscopic habitats of oil phase, technically the dispersed minuscule water droplets in the oil could be a better habitat that containing the indigenous microorganisms.
Highlights
Subsurface petroleum reservoir ecosystems are complex and generally considered extreme conditions, including hypoxic state, high temperature, pressure, salinity, and hydrophobicity (Li et al, 2007)
A review of microbial communities in natural oil reservoirs and associated environments showed that comparing to bacteria, archaea distribution in petroleum reservoir is less diverse (Li et al, 2017), but performing fundamental and even indispensable functions, such as hydrocarbon degradation (Khelifi et al, 2014; Mardanov et al, 2015), ammonia oxidation (Li et al, 2011), sulfate reduction (Stetter et al, 1987), and methanogenesis (Kleikemper et al, 2005), etc
To narrow the gap in our knowledge of how archaeal communities can differ between oil and aqueous phase and whether environmental factors promote substantial differences in microbial communities among production wells, we studied the taxonomic diversity of archaeal communities in both aqueous and oil phases from four production wells in the high-temperature petroleum reservoir
Summary
Subsurface petroleum reservoir ecosystems are complex and generally considered extreme conditions, including hypoxic state, high temperature, pressure, salinity, and hydrophobicity (Li et al, 2007). It harbors wide distribution of anaerobic microorganisms including sulfate-reducing bacteria, nitrate-reducing bacteria, fermentative bacteria, syntrophic bacteria, methanogens, and many more microorganisms A better knowledge of the archaea ecology in petroleum reservoirs is of great importance (Head et al, 2003; Aitken et al, 2004)
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