Data di Pubblicazione:
2011
Citazione:
Unravelling extremophiles diversity of volcanic habitats / F. Mapelli, R. Marasco, E. Rolli, D. Daffonchio, D. Rouwet, F. Tassi, G. Chiodini, S. Borin. ((Intervento presentato al 1. convegno International Conference of Microbial Diversity “Environmental Stress and Adaptation tenutosi a Milano nel 2011.
Abstract:
Introduction
Acidic habitats of natural origin are broadly distributed on the Earth. Nevertheless little is known about the microbial diversity of these extreme ecosystems, generally originated by volcanic and hydrothermal activities. Since their values of temperature, pH and concentration of chemicals are close to known limits for life, they represent challenging habitats for those microorganisms that normally colonize conventional environments and only a small fraction of Bacteria are expected to thrive in such a harsh type of ecosystem. Extremophiles inhabiting volcanic habitats, including crater lakes and hot springs, are of interest to microbiologists for their potential biotechnological application.
In this study the composition of the microbiome inhabiting acidic water samples collected from six crater lakes located in Costa Rica (Río Cuarto, Hule, Irazú, Botos and Poás) and Mexico (El Chichón) was investigated. Furthermore the bacterial community able to colonize water collected from three different sites of an acidic Icelandic hot-spring was analyzed.
Main purposes of the present work were (i) to explore the phylogenetic diversity of Bacteria adapted to the peculiar physio-chemical conditions and (ii) the understanding of the microbiome’s composition shaping forces in natural acidic waters. In order to overcome the low level of cultivability of environmental bacteria, the Denaturing Gradient Gel Electrophoresis (DGGE) fingerprinting technique was applied on the metagenome extracted from the lake waters. Moreover, cultivation dependent methods were applied to investigate the physiological capabilities of the microorganisms that colonize thermal spring field related to the El Chichón volcanic system, where pioneering vascular plants were retrieved. Establishment of tight interplay of microbes and plants are well known to occour in many different type of extreme environments (Puente et al., 2004; Siddikee et al., 2010) For this reason a special attention has been dedicated to plant growth promoting (PGP) rhizobacteria, with the aim of discovering bacteria able to aid the plant to cope with the inhospitable environmental conditions.
Materials and Methods
Water samples were collected in March 2010 at different depths along a vertical profile of the water column from 1 m to the maximum depth for Laguna Hule (H), Río Cuarto (RC) and Botos (B) lakes. Water samples were collected from different sites at the surface layer in the case of Poás, Irazú (LN09, LE09, LE10) and El Chichón (LE, SP, AS8, ASgas) volcanic lakes (December 2009 and March 2010) and from the Icelandic hot-spring (P). Immediately after collection the water samples (0.1 to 0.5 l) have been filtered through Sterivex filters with 0.2-m pore size (Millipore). After adding RNA Later the filters were stored at –20°C until DNA extraction. The rhizosphere of a single individual of vascular plants observed in the acidic (pH 4.1) SO4-type steam-heated pools (T 42°C) within the Soap Pool field (SP) of El Chichón system was collected, stored in a sterile bag and transferred to the laboratory for cultivation experiments.
Temperature, pH, conductivity and redox potential were measured in-situ using a CTD profiler.
For details about the applied molecular and cultivation methods please refer to the manuscript in preparation (Mapelli et al.)
Results and discussion
The geochemistry of some of the Laguna Húle, Río Cuarto, Botos and Poás lakes was deeply studied in the last decades (Tassi et al., 2009), nevertheless few data are available about the microbiome composition of these extreme habitats.
DGGE fingerprinting results showed the highest number of bands in the samples collected along the depth profiles of Laguna Húle and Río Cuarto lake
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Elenco autori:
F. Mapelli, R. Marasco, E. Rolli, D. Daffonchio, D. Rouwet, F. Tassi, G. Chiodini, S. Borin
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