Diversity of microbial communities in production and injection waters of algerian oilfields revealed by 16S rRNA gene amplicon 454 pyrosequencing

The microorganisms inhabiting many petroleum reservoirs are multi-extremophiles capable of surviving in environments with high temperature, pressure and salinity. Their activity influences oil quality and they are an important reservoir of enzymes of industrial interest. To study these microbial assemblages and to assess any modifications that may be caused by industrial practices, the bacterial and archaeal communities in waters from four Algerian oilfields were described and compared. Three different types of samples were analyzed: production waters from flooded wells, production waters from non-flooded wells and injection waters used for flooding (water - bearing formations). Microbial communities of production and injection waters appeared to be significantly different. From a quantitative point of view, injection waters harbored roughly ten times more microbial cells than production waters. Bacteria dominated in injection waters, while Archaea dominated in production waters. Statistical analysis based on the relative abundance and bacterial community composition (BCC) revealed significant differences between production and injection waters at both OTUs 0.03 and phylum level. However, no significant difference was found between production waters from flooded and non-flooded wells, suggesting that most of the microorganisms introduced by the injection waters were unable to survive in the production waters. Furthermore, a Venn diagram generated to compare the BCC of production and injection waters of one flooded well revealed only 4% of shared bacterial OTUs. Phylogenetic analysis of bacterial sequences indicated that Alpha- , Beta- and Gammaproteobacteria were the main classes in most of the water samples. Archaeal sequences were only obtained from production wells and each well had a unique archaeal community composition, mainly belonging to Methanobacteria , Methanomicrobia , Thermoprotei and Halobacteria classes. Many of the bacterial genera retrieved had already been reported as degraders of complex organic molecules and pollutants. Nevertheless, a large number of unclassified bacterial and archaeal sequences were found in the analyzed samples, indicating that subsurface waters in oilfields could harbor new and still-non-described microbial specie

Etude de la biodiversité microbienne dans les écosystèmes aquatiques pétroliers

102 p. : ill. ; 30 cm.Les micro-organismes habitant de nombreux gisements pétroliers sont des multiextrêmophiles capables de survivre dans des environnements ou règne de hautes températures, pressions et salinités. Leurs activités influencent la qualité du pétrole et sont aussi un important réservoir d’enzymes d'intérêts industriels. Afin d’étudier la composition de cette communauté microbienne et évaluer les modifications qui pourraient être causées par les pratiques industrielles, les communautés bactériennes et archéennes présentent dans les eaux de quatre champs pétrolifères algériens ont été décrites et comparées. Trois différents types d'échantillons ont été analysés : les eaux de production de puits touchés par les eaux d’injection, les eaux de production non touchées par les eaux d’injection et des eaux d’injection. Les communautés microbiennes des eaux de production semblent être sensiblement différentes de celles des eaux d'injection. D'un point de vue quantitatif, les eaux d'injection abritaient environ dix fois plus de cellules microbiennes que les eaux de production. Les bactéries dominent dans les eaux d’injection, tandis que les archées dominent dans les eaux de production. L'analyse statistique basée sur l'abondance relative et la composition de la communauté bactérienne (CCB) a révélé des différences significatives entre les eaux de production et les eaux d’injection aussi bien au niveau OTUs0.03 qu’au niveau phylum. Toutefois, aucune différence significative n'a été retrouvée entre les eaux de production touchées ou non touchées par les eaux d’injection, ce qui suggère que la plupart des micro-organismes introduits par l'eau d'injection ont été incapables de survivre dans les eaux de production. En outre, un diagramme de Venn généré pour comparer la CCB d’une eau de production avec son eau d’injection a révélé que seulement 4% des OTUs bactériennes sont communes à ces deux types d’eaux. L'analyse phylogénétique des séquences bactériennes indiquait que Alpha, Beta et Gammaproteobacteria étaient les principales classes retrouvées dans la plupart des échantillons d'eaux. Les séquences d'archées ont été obtenues seulement à partir des eaux de production et chaque puits avait une composition unique en communauté archaeal, appartenant principalement aux classes des Methanobacteria, Methanomicrobia, Thermoprotei et Halobactéries. Plusieurs genres bactériens recensés avaient déjà été rapportés comme dégradeurs de molécules et de polluants organiques complexes. Néanmoins, un grand nombre de séquences de bactéries et d'archées non classées ont été retrouvés dans ces échantillons analysés, ce qui indique que les eaux souterraines des champs pétrolifères pourraient abriter de nouvelles espèces microbiennes non encore décrite jusqu'à l’heure actuell

Diesel Biodegradation Capacities and Biosurfactant Production in Saline-Alkaline Conditions by Delftia sp NL1, Isolated from an Algerian Oilfield

In this study, a diesel oil-degrading bacterium was isolated from an oilfield water injection (water-bearing formations, 1,205 m depth) in Algeria. The bacterial strain, designated NL1, was cultivated on diesel oil as sole carbon and energy sources. Molecular analyses of the 16S rRNA gene sequence (KY397882) placed NL1 strain closely related to distinct cultivated species of the Delftia genus. Optimal diesel oil biodegradation by Delftia sp NL1 strain occurred at pH 11, 40 °C, 2 M NaCl and initial hydrocarbon concentration of 5% (v/v) as sole carbon source. GC-MS analyses evidenced that strain Delftia sp NL1 was able to degrade more than 66.76% of diesel oil within only 7 days. On the other hand, and in the same conditions, biosurfactant production by Delftia sp NL1 was also evaluated evidencing high emulsifying capacity (E24 = 81%), ability to lower the surface tension of growing media (with the value of 25.7 mN m− 1), and production of glycolipids (8.7 g L−1) as biosurfactants. This research presents indigenous strain Delftia sp NL1 for diesel degradation and synthesis of biosurfactant in extreme conditions. In this sense, strain NL1 is a good candidate for possible in situ oil recovery and in wastewater treatment in refineries and oil terminals in petroleum industry.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Identification and Phylogenetic Analyses of Anaerobic Sulfidogenic Bacteria in Two Algerian Oilfield Water Injection Samples

Corrosion of metallic oilfield pipelines by microorganisms is a costly but poorly understood phenomenon. For the first time, sulfidogenic communities in injection waters of two Algerian oilfields, Tin Fuin Tabankort (IT3) and Stah (IS2) were examined using the 16S rRNA gene cloning and sequencing approach. Water samples were inoculated into selective medium for sulfate-reducing bacteria and incubated under anaerobic conditions at 45 °C. The total number of culturable sulfidogenic microorganisms in the samples obtained from the two sampled waters (IT3 and IS2) was 2.4 × 105 cells/mL and 3.9 × 104 cells/mL, respectively. Scanning electron microscopy analyses showed different morphological forms reflecting the diversity of sulfidogenic communities. 16S rRNA gene sequencing and phylogenetic diversity analyses revealed that both water reservoirs harbor large amounts of anaerobic bacteria. However, a majority of all the sequences analyzed (e.g. 34% in the IS2 and 84% in the IT3 samples) were not assigned to any known bacterial group, suggesting that subsurface waters harbor very large sulfidogenic anaerobic microbial communities of as yet undescribed bacterial phyla. Proteobacteria were found to be the most dominant phylum in the IS2 sample (49%); however, no Proteobacteria were detected at the IT3 production well. The Firmicutes phylum (10%) was detected in the two water samples, whereas Bacteroidetes phylum (7%) was retrieved only in IT3. The most abundant related genera were: Desulfotomaculum, Porphyrobacter, Hyphomicrobium, Acidocella, Comamonas, Ramlibacter, Pseudomonas, Enterobacter and Flavitalea. No shared operational taxonomic units were observed among the two samples analyzed, demonstrating the uniqueness of each subsurface water well. This study demonstrates the diversity of the sulfidogenic bacteria that might play a critical role in the souring mediated corrosion of metallic oilfield pipelines. This information could help oilfield companies develop better anticorrosion treatments and strategies.SCOPUS: ar.jDecretOANoAutActifinfo:eu-repo/semantics/publishe