Antarctic epilithic lichens as niches for black meristematic fungi.

Laura Selbmann,Laura Zucconi,Daniela Isola,Silvano Onofri,Martin Grube

doi:10.3390/biology2020784

Abstract

Sixteen epilithic lichen samples (13 species), collected from seven locations in Northern and Southern Victoria Land in Antarctica, were investigated for the presence of black fungi. Thirteen fungal strains isolated were studied by both morphological and molecular methods. Nuclear ribosomal 18S gene sequences were used together with the most similar published and unpublished sequences of fungi from other sources, to reconstruct an ML tree. Most of the studied fungi could be grouped together with described or still unnamed rock-inhabiting species in lichen dominated Antarctic cryptoendolithic communities. At the edge of life, epilithic lichens withdraw inside the airspaces of rocks to find conditions still compatible with life; this study provides evidence, for the first time, that the same microbes associated to epilithic thalli also have the same fate and chose endolithic life. These results support the concept of lichens being complex symbiotic systems, which offer attractive and sheltered habitats for other microbes.

Highlights

Black meristematic fungi are known to be tolerant to extreme environmental conditions
Owing to the stress pressure of the sites where they normally occur, black meristematic fungi are rarely found in complex microbial populations, rather they occur alone or in association with similar stress resistant organisms such as lichens [13,14] and cyanobacteria [15]
Other organisms can participate in these communities, in particular bacteria, cyanobacteria and non-lichenized fungi [18±20], but their biodiversity, their role and interactions are still scarcely investigated

Summary

Introduction

Black meristematic fungi are known to be tolerant to extreme environmental conditions. The term black fungi embraces a polyphyletic group of fungi that share some phenotypic characters such as melanized cell walls and meristematic development, which seem to support survival and persistence in hostile environmental conditions They are commonly isolated from environments that are almost devoid of other eukaryotic life-forms, including saltpans [1], acidic and contaminated sites [2±4], exposed rocks in dry and extremely hot or cold climates, ranging from hot deserts [5], the Mediterranean [6] to the Antarctic [7] and on monuments [8±12]. The rock black fungi represent a peculiar group of colonizers [7,17]

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