Analysis of the composition of bacterial communities in oil reservoirs from a southern offshore Brazilian basin

Abstract

The aim of this study was to characterize and compare the bacterial community structure of two distinct oil samples from a petroleum field in Brazil by using both molecular, based on the construction of 16S rRNA gene libraries, and cultivation methods. Statistical comparisons of libraries based on Amplified Ribosomal DNA Restriction Analysis (ARDRA) data revealed no significant differences between the communities recovered in the non-biodegraded (NBD) and highly biodegraded oils (HBD). BlastN analysis of the 16S rRNA gene sequences representative of distinct ribotypes from both oils showed the presence of nine different bacterial genera in these samples, encompassing members of the genera Arcobacter, Halanaerobium, Marinobacter, Propionibacterium, Streptomyces, Leuconostoc, Acinetobacter, Bacillus and Streptococcus. Enrichments obtained using oil as inoculum and sole carbon source yielded bacterial isolates showing high 16S rRNA gene sequence similarity with Achromobacter xylosoxidans, Bacillus subtilis, Brevibacillus sp., Dietzia sp. and Methylobacterium sp. Comparison between the data obtained using cultivation-independent and enrichment cultures suggests that different selection of community members may occur when using distinct approaches. All the organisms found, except for Leuconostoc sp. and Streptococus sp., have been previously reported in the literature as hydrocarbon degraders and/or associated to oil field environments.

Taxonomy, Epidemiology, and Clinical Relevance of the Genus Arcobacter

“…Recently published 16S rRNA gene phylogenetic analysis, constructed with nearly full-length 16S rRNA gene sequences of uncultured or not-yet-described species (Ͼ1,300-bp sequences deposited up to October 2009 at the MSU Ribosomal Database Project) (W. Miller personal communication) in combination with sequences of known Arcobacter spp., revealed that the new phylogenetic lines waiting to be described outnumber those already known (162). These potentially new Arcobacter species come from very different hosts and/or habitats, i.e., activated sludge and sewage, oil field environments, tidal and marine sediments, seawater, estuarine and river water, plankton, coral, tubeworms, snails, oysters, abalone, and associated with cod larviculture or with cyanobacterial mats (31,44,130,136,145,162). Although most of them are sequences from uncultured bacteria, it is likely that several new species will be proposed in the near future.…”

Composition of Bacterial Communities Isolated from Core Samples Taken from Petroleum Deposits

“…14,33 Some sulfate reducing bacteria and fermentative bacteria were also detected in our study but in comparatively lower percentages, which might be related to the conditions in the reservoir or isolation technique.…”

“…We found some bacteria showing similarity to Streptococcus sp. Presence of other oil degraders in the population as documented by Sette et al (2007) was not evident. In petroleum reservoirs, anaerobic conditions exist, and oil degradation is mainly mediated by methanogenesis.…”

“…[12][13][14][15] Amplified ribosomal DNA restriction analysis (ARDRA) 12 is one of the simplest and most cost-effective techniques for culture-independent description of bacterial communities. 16 For several environmental samples such as soil or seawater, the proportion of cells that can be cultured is estimated to be 0.1% or at most 10% of the total population, 17 and few data are available concerning how closely they reflect the actual composition of these communities.…”

Microbial biodiversity in a Malaysian oil field and a systematic comparison with oil reservoirs worldwide

“…Despite this, our knowledge of the microbes in petroleum reservoirs remains limited. To date, cultureindependent microbial surveys have been conducted on relatively few sites-in Canada (Voordouw et al 1996;Grabowski et al 2005), USA (Orphan et al 2000), the North Sea (Dahle et al 2008), China (Li et al 2006(Li et al , 2007a, Brazil (Sette et al 2007;Oliveira et al 2008) and Australia (Li and Hendry 2008). While studies have been conducted at local individual Weld sites, no systematic comparison of the microbial communities across oil reservoirs worldwide has yet been reported.…”