![]() 3–7 In a recent investigation of microbial ecology of a water flooded oil reservoir, it was concluded that microorganisms present in the injection water have major effects on the microbial compositions of oil reservoirs. It is not, therefore, surprising to detect mostly facultative and aerobic microbes in samples from oil reservoirs. These activities invariably result in the introduction of some exogenous microbes and disappearance of some indigenous communities. 1 In practice, microbial populations of oil reservoirs are usually disturbed and significantly altered during the production process, 2 especially during the microbial enhanced oil recovery (MEOR) process with nutrient injection for in situ stimulation of microbes. Natural untouched oil reservoirs usually have low redox potentials and limited electron donors and acceptors, and only strict anaerobes can normally survive, be active and be truly considered indigenous in them. Introduction It is a well-established fact that oil reservoirs harbor and sustain diverse microbial communities. Based on these findings, a suggestion of re-optimization of the boost nutrients, targetting the microbes co-existing in the injection water and the oil reservoir and having survival ability in both surface and subsurface environments, rather than simple repeats for the subsequent in situ MEOR applications was proposed. ![]() Additionally, microbes only dominant in the production waters were significantly inhibited with a sharp decline in their relative abundance. Alterations of microbial community after the injection of boost nutrients showed that microbes giving positive responses were mainly those belonging to the genera of Comamonas, Brevundimonas, Azospirillum, Achromobacter, Pseudomonas, and Hyphomonas, which were detected both in the injection water and in the production water and usually detected in oil reservoir environments or associated with hydrocarbon degradation. There was a close microbial community compositional relationship between the injection water and the successful first round MEOR processed oil reservoir which was indicated by the result of 43 shared dominant operational taxonomic units detected in both the injection water and the production water. Published by Oxford University Press.Using 454 pyrosequencing of 16S rRNA gene amplicons, microbial communities in samples of injection water and production water during a serial microbial enhanced oil recovery (MEOR) field trial in a water flooded high pour point oil reservoir were determined. Supplementary data are available at Bioinformatics online. Our software is designed for ease of use, operating at least 7x faster than existing solutions, despite requiring 10x less memory.Ĭ ++ and R source code (GPL v.2) as well as binaries are available from and from CRAN or information: Here we present a software package for rarefaction analysis of large count matrices, as well as estimation and visualization of diversity, richness and evenness. Although classical numerical ecology methods provide a robust statistical framework for their analysis, software currently available is inadequate for large datasets and some computationally intensive tasks, like rarefaction and associated analysis. The rapidly expanding microbiomics field is generating increasingly larger datasets, characterizing the microbiota in diverse environments.
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