|129-2||Environmental factors influencing microbial community structure at Aconcagua river (central Chile) estuary bank soil|
|Autores:||Sebastián Fuentes (USM - Laboratorio de Microbiología, Universidad Santa María) ; Guochun Ding (JKI - Julius-Kühn Institute) ; Franco Cárdenas (USM - Laboratorio de Microbiología, Universidad Santa María) ; Kornelia Smalla (JKI - Julius-Kühn Institute) ; Michael Seeger (USM - Laboratorio de Microbiología, Universidad Santa María) |
Aconcagua river in central Chile is used for diverse human activities along the river's valley. Mining, agriculture and domestic uses of the river have been reported. In addition, a crude-oil refinery is located close to the river mouth. In this study, the river mouth was regarded as a resume of all activities taking place upstream. An exploratory study on microbial communities in the estuary bank soils was performed by culture independent techniques. Five sites were analyzed from the sea shoreline and ~500m distance one to each other. Denaturant gradient gel electrophoresis (DGGE) fingerprints analysis revealed differences in Bacteria and Fungi communities from the different sites. Microbial communities from the two sites closer to sea were similar. Microbial communities from the two sites located more upstream were also similar. The fingerprints of the central site reflect a transition between the upstream and downstream sites. Similar patterns for Alphaproteobacteria y Betaproteobacteria, Actinobacteria and Bacilli were observed. Pseudomonas genus structure was homogeneous along the sampled area. Policyclic aromatic hydrocarbon ring hydroxilating dioxygenases (PAH-RHD) genes were detected only in the three sites located upstream. Some of these catabolic genes are closely related to those from Beta- (Delftia, Comamonas, Ralstonia) and Gamma-proteobacteria (Pseudomonas). Plasmids belonging to the main incompatibility groups associated to xenobiotic degradation and metal resistance (IncP-1, IncP-7 and IncP-9) showed heterogeneous distribution along the five sites. Petroleum hydrocarbons were present in low amounts in the sites. Phosphorus, potassium, calcium, magnesium, zinc, iron and arsenic levels varied between sites. Differences in pH and sodium content were also seen. Statistical analysis to correlate the environmental variables and community structure differences are conducted in order to unveil the factors that affect the microbial communities of the Aconcagua river mouth.
Acknowledgements: CONICYT (SF) and MECESUP-FMS0710 (SF&FC) PhD fellowships, CONICYT-AT-24100177 (SF) and CONICYT-AT-24121602 (FC), FONDECYT1110992 (MS), USM131109 (MS) and CN&SB grants.
Palavras-chave: Community, Soil, DGGE, Bacteria