Bacterial diversity of autotrophic enriched cultures from remote, glacial Antarctic, Alpine and Andean aerosol, snow and soil samples

E González-Toril,R J Delmas,J.-R Petit,R Amils,J Elster,J Komárek

doi:10.5194/bg-6-33-2009

Abstract

Abstract. Four different communities and one culture of autotrophic microbial assemblages were obtained by incubation of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas), in a minimal mineral (oligotrophic) media. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. Phylogenetic comparison with the currently available rDNA database allowed sequences belonging to Proteobacteria Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla to be identified. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the marine Antarctic soil the poorest (only one). Snow samples from Col du Midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteriaclone). The only microorganism identified in the Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. Most of the identified microorganisms had been detected previously in cold environments, marine sediments soils and rocks. Air current dispersal is the best model to explain the presence of very specific microorganisms, like those identified in this work, in environments very distant and very different from each other.

Highlights

Long distance dispersal of biological particles produced by atmospheric circulation, ocean currents, birds, fish, mammals and human vectors, has been known since the mid 20th century (Gislen, 1948; Gregory, 1967; Schnell and Vali, 1972; Marshall, 1996a, b; Vincent, 2000)
Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain
Snow samples from Col du Midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones)

Summary

Introduction

Long distance dispersal of biological particles produced by atmospheric circulation, ocean currents, birds, fish, mammals and human vectors, has been known since the mid 20th century (Gislen, 1948; Gregory, 1967; Schnell and Vali, 1972; Marshall, 1996a, b; Vincent, 2000). As a product of this study cultivable autotrophic pigmented microorganisms were obtained from alpine snow (Alps and Andes) and aerosol (Antarctic) samples It has been suggested (Imshsnetsky et al, 1978, Christner et al, 2000) that the presence of highly pigmented bacterial colonies in the mesosphere and in glacial ice was associated with the need to protect cells from harmful UV-radiation during atmospheric transport and exposure on the surface of the glaciers. Similar bacterial specimens have been observed in soils in the Arctic Svalbard (unpublished data, Øehakovaet al., 2009) These observations support the idea that this type of microorganisms commonly develop in cold desert ecosystems and are transported via aerosol to both, short and long distances. For comparison the culture of pigmented bacteria isolated from marine Antarctic soil (King George Island, South Shetland) was analysed

Site description and sample collection

Sample preparation and cultivation

DNA extraction

Clone library analysis

Results and discussion