PROIMI   05436
PLANTA PILOTO DE PROCESOS INDUSTRIALES MICROBIOLOGICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Investigation of neutrophilic iron bacteria communities in Tierra del Fuego wetlands
Autor/es:
SCHMIDT B; SANCHEZ L. A,; KREPS G.; FRETSCHNER T.; FERRERO, M.; SIÑERIZ F.; SZEWZYK U.
Lugar:
Copenhagen
Reunión:
Congreso; ISME - The power of the small; 2012
Institución organizadora:
International Society for Microbial Ecology
Resumen:
Iron bacteria have been in focus of microscopists and microbiologists for a long time due to their capability to form eye-catching reddish brown ochre deposits. Microscopic examinations led to description of many species of iron bacteria following mainly morphologic features in natural samples or enrichment cultures. Pure cultures and therefore descriptions fulfilling current requirements are lacking. Diversity of available cultivated strains is therefore by far not reflecting the vast diversity which is apparent in environmental samples. In many wetlands of Tierra del Fuego/Argentina large amounts of ochre colored sediments and fluffy layers on underwater surfaces can be found. These phenomena are obviously caused by masses of iron bacteria developing in slow flowing iron rich water with dissolved organic carbon content in particular humic substances. Although open water is typically rich in dissolved oxygen, small-scale contact of aerobic, microaerobic and anaerobic zones is present in sediments. In these interfaces iron is changing between ferrous and ferric state and therefore might undergo a biological catalyzed fast redox cycling and thus influence cycles of elements like carbon in these environments. The aims of this work were to study bacterial communities involved in iron oxidation and deposition and to compare the results to data from similar habitats on the northern hemisphere namely Norway and Germany. Samples of sediments, microbial mats and thin layer biofilms grown on exposed glass slides were examined microscopically. In addition, molecular biological methods were used to analyze bacterial communities. Cultivation was performed to enrich and isolate aerobic heterotrophic iron bacteria from these sampling sites. The isolates were characterized phylogenetically to clarify their taxonomic position and examined regarding phenotypic features. Microscopy showed a high abundance as well as a wide morphological diversity of iron incrusted structures of bacterial origin. The composition of iron depositing communities differed between sampling sites and sampling dates indicating a dynamic variation of the populations. Cultivation on solid media led to isolation of more than 70 iron bacteria strains predominantly belonging to the beta subclass of Proteobacteria. Sequence analysis of 16S rDNA and other genes showed that some of the strains belong to long known iron bacteria taxa like Sphaerotilus-Leptothrix group. In some cases isolates are representing species which are not cultivated until today or might have been cultivated but lost before genetic analyses were available. Other strains belong to groups which have not been known to deposit iron before.