Spatial isolation and environmental factors drive distinct bacterial and archaeal communities in different types of petroleum reservoirs in China.

Peike Gao,Yansen Wang,Bing Zeng,Guoqiang Li,Yanshu Li,Jinxia Xie,Jiefang Zhou,Ting Ma,Yan Li,Huimei Tian

doi:10.1038/srep20174

Abstract

To investigate the spatial distribution of microbial communities and their drivers in petroleum reservoir environments, we performed pyrosequencing of microbial partial 16S rRNA, derived from 20 geographically separated water-flooding reservoirs, and two reservoirs that had not been flooded, in China. The results indicated that distinct underground microbial communities inhabited the different reservoirs. Compared with the bacteria, archaeal alpha-diversity was not strongly correlated with the environmental variables. The variation of the bacterial and archaeal community compositions was affected synthetically, by the mining patterns, spatial isolation, reservoir temperature, salinity and pH of the formation brine. The environmental factors explained 64.22% and 78.26% of the total variance for the bacterial and archaeal communities, respectively. Despite the diverse community compositions, shared populations (48 bacterial and 18 archaeal genera) were found and were dominant in most of the oilfields. Potential indigenous microorganisms, including Carboxydibrachium, Thermosinus, and Neptunomonas, were only detected in a reservoir that had not been flooded with water. This study indicates that: 1) the environmental variation drives distinct microbial communities in different reservoirs; 2) compared with the archaea, the bacterial communities were highly heterogeneous within and among the reservoirs; and 3) despite the community variation, some microorganisms are dominant in multiple petroleum reservoirs.

Highlights

To investigate the spatial distribution of microbial communities and their drivers in petroleum reservoir environments, we performed pyrosequencing of microbial partial 16S rRNA, derived from 20 geographically separated water-flooding reservoirs, and two reservoirs that had not been flooded, in China
Studies of oil reservoir ecosystems have improved our understanding of these biogeochemical cycles[4,5,6,7,8] and the mechanisms that microorganisms use to tolerate the extreme underground environments[9]
The results suggest that spatial isolation, represented by sampling location, temperature, and the salinity of the formation brine, explained the variation in the microbial communities well

Summary

Introduction

To investigate the spatial distribution of microbial communities and their drivers in petroleum reservoir environments, we performed pyrosequencing of microbial partial 16S rRNA, derived from 20 geographically separated water-flooding reservoirs, and two reservoirs that had not been flooded, in China. Petroleum reservoirs are composed of multiple oil-bearing strata, of low porosity and low permeability, and represent complex oligotrophic ecosystems These extreme environments can harbour diverse bacteria and archaea that exhibit strong adaptations to the oligotrophic and oxygen-deficient conditions[1,2,3]. There is growing evidence that free-living microorganisms exhibit non-random distribution patterns across diverse habitats, at various temporal and spatial scales[24,25,26,27,28,29,30] Environmental variables, such as day–night differences[31], temperature[32,33], salinity[34], pH24,35, and nutrients[15,36] appear to be the major determinants of microbial community composition. The aim of this study was to determine the composition and spatial distribution of the bacterial and archaeal communities and determine the major environmental variables (mining patterns, spatial isolation, temperature, salinity, and pH) in shaping their composition and structure across a broad range of physical and geochemical reservoirs

Objectives

Methods

Results

Conclusion