Differential Composition of Lichen Microbiomes in Cladonia gracilis According to the Positions at Thalli from King George Island, Antarctica

초록

Lichens are symbiotic organisms that are majorly composed of lichenized fungi (mycobiont) and green algae/or cyanobacteria (photobiont). However, lichen thalli also contain highly diverse microbes (microbionts) such as bacteria, archaea, and fungi. Cladonia may provide different micro-environments to the microbial communities of Cladoia gracilis from King George Island, Antarctica. To reveal the microbial communities of different parts of the lichenized fungi, we sectioned thalli from center, intermediate, and marginal positions of colonies to apical, middle and basal parts. Since apical parts are usually more exposed to sun light and wind, and has lower humidity compared to basal parts, we considered this sectioning to represent different conditions. Bacterial 16S rRNA gene and eukaryotic nuclear large subunit (LSU) rRNA gene were analyzed by 454 pyrosequencing method. Apical parts of thalli contained relatively simple bacterial communities, basal parts contained more complex with diverse phyla. LSU sequences were mostly composed of diverse Cladonia genotypes. Algae and cyanobacteria which are related in photosynthesis are represented in different parts of thalli. Although Cyanobacteria OTUs are enriched on basal parts, major algal OTUs concentrated on apical and middle parts. Considering these results, we conclude that different compositions of lichen microbiome according to the vertical position would depend on the micro-environmental conditions.