Population Dynamics within a Microbial Consortium during Growth on Diesel Fuel in Saline Environments

Abstract

The diversity and dynamics of a bacterial community extracted from an exploited oil field with high natural soil salinity near Comodoro Rivadavia in Patagonia (Argentina) were investigated. Community shifts during long-term incubation with diesel fuel at four salinities between 0 and 20% NaCl were monitored by singlestrand conformation polymorphism community fingerprinting of the PCR-amplified V4-V5 region of the 16S rRNA genes. Information obtained by this qualitative approach was extended by flow cytometric analysis to follow quantitatively the dynamics of community structures at different salinities. Dominant and newly developing clusters of individuals visualized via their DNA patterns versus cell sizes were used to identify the subcommunities primarily involved in the degradation process. To determine the most active species, subcommunities were separated physically by high-resolution cell sorting and subsequent phylogenetic identification by 16S rRNA gene sequencing. Reduced salinity favored the dominance of Sphingomonas spp., whereas at elevated salinities, Ralstonia spp. and a number of halophilic genera, including Halomonas, Dietzia, and Alcanivorax, were identified. The combination of cytometric sorting with molecular characterization allowed us to monitor community adaptation and to identify active and proliferating subcommunities.Many oil fields are located in semiarid regions characterized by soils of high natural salinity. Careless operation during oil extraction and processing contaminates the soil, for instance, via the generation of large volumes of oily and saline wastewater. Strategies are thus needed to effectively treat oil pollution of highly saline waters and soils.The degradation of hydrocarbons as major components of mineral oil is generally brought about by microorganisms. At the salinity of seawater (ϳ3% total salts, mainly NaCl) or below, most low-molecular-weight components of mineral oil are easily degraded by a variety of microorganisms. However, the range of degrading organisms decreases with increasing salinity. There are only a few reports on the degradation of hydrocarbons in hypersaline environments. Enrichment cultures from the Great Solar Lake grew on mineral oil at salinities up to 17.2% (70), and a bacterial consortium and an extremely halophilic archaeon grew on hexadecane and crude oil at salinities of 15% and 32%, respectively (5). Degradation of hydrocarbons (mainly n-alkanes) by archaea (Halobacteria) at 15 to 32% NaCl was also reported (40). An extremely halophilic archaeon from a salt marsh degraded various saturated and aromatic hydrocarbons at salinities of up to 31% and grew optimally at 22% NaCl (10). In our own laboratory, microbial communities from saline soils in Patagonia degraded diesel fuel up to a salinity of 17.5% (59). Although some members of the communities were identified, their contributions to the diesel fuel biodegradation remained obscure.Information on the phylogenetic diversity of microbial communities can be obtained by molecular methods, like...

Comparison of archaeal and bacterial community structures in heavily oil-contaminated and pristine soils

“…This should be related to relatively high salt content in the soil samples (Table 1). Similar results were observed by Kleinsteuber et al in a study about the population dynamics within a microbial consortium during growth on diesel fuel in saline environments (29), suggesting that Halomonas, Marinobacter, and Alcanivorax might be the primary hydrocarbondegraders under saline conditions.…”

Obligate oil-degrading marine bacteria

“…Nr. DQ337077; [28]), hydrocarbon-polluted saline soil ( [29]) and various geothermal areas in Italy and USA (Yellowstone) [30,31] (Figure 2). This ubiquity of A. borkumensis is presumably due to its capacity to grow on many saturated petroleum fraction constituents and on biogenic hydrocarbons: straight-chain and branched alkanes, isoprenoids, and long-side-chain alkyl compounds, including alkylmonocycloalkanes, alkylbenzenes, and organic alkyl-sulfuric compounds [32,33].…”

Functional metaproteome analysis of protein extracts from contaminated soil and groundwater

“…Gene probes are also used for a combination of fluorescence in situ hybridization (FISH) and microautoradiography (MAR) to assign structural and functional genes to single cells of microbial communities (Wagner et al, 2006). In liquid samples, population dynamics can be followed by multiparametric flow cytometry and phylogenetic identification of subcommunities by 16S ribosomal RNA (16S rRNA) gene sequencing (Kleinsteuber et al, 2006).…”