Studi molecolari su licheni antartici e microrganismi associati
Author(s)
Ruisi, Serena
Date Issued
October 22, 2008
Type
Doctoral Thesis
Abstract
Antarctic lichen samples collected in different localities from Northern and Southern Victoria Land (continental Antarctica), were analyzed to isolate the culturable diversity of associated microrganisms. Different lichen samples, collected from Antarctica and different localities of Austrian mountanis, belonging to the discussed Lecanora polytropa group, which include the antarctic endemic species Lecanora fuscobrunnea, were studied to define the group. The morphological, physiological and molecular analysis of the culturable fungal and bacterial populations and the molecular analysis of the Lecanora polytropa group are presented.
Lichens are symbiotic associations of fungi (mycobionts), green algae and/or cyanobacteria (photobionts). Since most lichens are long-living and slow growing organisms in diverse and sometimes extreme ecological conditions, they may provide a stable ecological niche for further microrganisms. Whereas the symbiotic components have been extensively described, the associated microrganisms inhabiting this niche has not
been well characterized. A morphological, physiological and molecular analysis of the
culturable fungal and bacterial populations isolated from lichens collected in different cold
areas from continental Antarctica is presented. Results demonstrate that lichens represent
an extremely rich “niche” hosting a wide diversity of microorganisms. The phylogenetic
analysis of fungal and bacterial isolates shows the presence of new taxa which will be
discussed in the next future. The lichen symbiosis might be thought as a community
hosting a wide diversity of microrganisms.
The genus Lecanora, a representing the largest order of lichenized fungi, Lecanorales, is
an example of a large and heterogeneous crustose genus. A molecular phylogeny, based on ITS and RPB1 mycobiont sequences analyses, of the Lecanora polytropa group is presented. The study includes saxicolous members of the group collected from different locations of Austrian mountains; a further collection was made from the Dry Valleys (Southern Victoria Land, Antarctica) and include samples of the endemic species Lecanora fuscobrunnea. The phylogenetic analysis show the presence of distinct and well supported
clusters, suggesting the poliphyletic behaviour of the species belonging to the Lecanora
polytropa group, although the species analyzed are not strongly morphologically different.
Additional information
Dottorato di ricerca in Evoluzione biologica e biochimica
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