Altitude and fungal diversity influence the structure of Antarctic cryptoendolithic Bacteria communities

Abstract

Summary Endolithic growth within rocks is a critical adaptation of microbes living in harsh environments where exposure to extreme temperature, radiation, and desiccation limits the predominant life forms, such as in the ice‐free regions of Continental Antarctica. The microbial diversity of the endolithic communities in these areas has been sparsely examined. In this work, diversity and composition of bacterial assemblages in the cryptoendolithic lichen‐dominated communities of Victoria Land (Continental Antarctica) were explored using a high‐throughput metabarcoding approach, targeting the V4 region of 16S rDNA. Rocks were collected in 12 different localities (from 14 different sites), along a gradient ranging from 1000 to 3300 m a.s.l. and at a sea distance ranging from 29 to 96 km. The results indicate Actinobacteria and Proteobacteria are the dominant taxa in all samples and defined a ‘core’ group of bacterial taxa across all sites. The structure of bacteria communities is correlated with the fungal counterpart and among the environmental parameters considered, altitude was found to influence bacterial biodiversity, while distance from sea had no evident influence.

Beyond the extremes: Rocks as ultimate refuge for fungi in drylands

“…B. frigida, in particular, is a crustose endemic lichen widely found in both coastal and mountain locations across the continent (Jones et al 2015). Recently, with the advent of next-generation sequencing methods such as pyrosequencing and metabarcoding, both prokaryotic and eukaryotic diversity have been characterized more deeply in these microbial ecosystems (Archer et al 2017;Coleine et al 2018aColeine et al , 2019. The majority of fungal sequences obtained from Coleine and coworkers belonged to Lecanoromycetes as members of families Caliciaceae, Acarosporaceae, Lecideaceae, and Lecanoraceae, whereas three genera (Buellia, Lecidea, and Acarospora) were predominant and among "core" (i.e., species retrieved in at least 75% of analyzed samples) members of analyzed samples.…”

Uncovered Microbial Diversity in Antarctic Cryptoendolithic Communities Sampling Three Representative Locations of the Victoria Land

“…Several factors have been identified that may putatively influence Antarctic cryptoendolithic distributions, both abiotic (e.g., sun exposure, altitude) [17,18,41] and biotic (fungi-bacteria interaction) [19]. In this study, the impact of habitat has been investigated.…”

“…Recent molecular studies are providing new insights into the distribution, biodiversity and composition of the Antarctic cryptoendolithic communities and a new understanding of their response to environmental pressure is arising [13][14][15][16][17][18][19]. Besides, these studies clearly highlighted that biodiversity is highly variable in rock samples, not only from different localities, but also for rocks coming right from the same locality [13].…”

Antarctic cryptoendolithic bacterial lineages of pre-Cambrian origin as proxy for Mars colonization

“…In the Antarctic desert areas, the Lichen-Dominated Communities (LDC) are the most complex and successful 5 . Recently, next-generation sequencing studies have brought new insights into their composition, showing that Lecanoromycete lichens and free living fungi in the Dothideomycetes (Ascomycota) are the dominant heterotrophic eukaryotes, while Actinobacteria and Proteobacteria are the most abundant Bacteria 12,13 . Due to their ubiquity in deserts and low taxonomic complexity and biodiversity 14 , endoliths are important study systems to understand evolutionary processes in the early history of life, to model how life evolves during the progression of desertification, and the extreme aridity approaches the limits of life providing a model for searches for life elsewhere in the Solar System.…”

“…The most common phylum, both in terms of number and abundance of CBS (estimated by the fraction of mapped reads, Fig. 1e, f, Supplementary Table 2), was Actinobacteria with 101 CBS (median percentage of mapped reads 27.2%, IQR 29.5%), followed by Chloroflexi and Proteobacteria , that are 'core' members of Antarctic endolithic communities 12 . The identified MAGs significantly increase the repertoire of known genomic data for several taxa, and represent the first example of bacterial genomes recovered from endolithic communities.…”