New subgroup of Bacteroidetes and diverse microorganisms in Tibetan plateau glacial ice provide a biological record of environmental conditions

Abstract

We recovered microorganisms from five ice core samples from three glaciers (Puruogangri, Malan, and Dunde) located in the Tibetan Plateau in China and analyzed their small subunit rRNA gene sequences. Most of the bacterial sequences were unknown previously; the most closely related known sequences were from bacteria of the Proteobacteria, Bacteroidetes, and Actinobacteria phyla. Chlorophyta, Streptophyta, Ciliophora, and fungal groups were represented among the 18S rRNA gene sequences that we obtained. The most abundantly represented glacial bacteria were Bacteroidetes, and Chlamydomonas was the predominant eukaryote. Comparative analysis showed that the Bacteroidetes sequences obtained from this study were highly similar to one another but most were only distantly related to previously characterized Bacteroidetes (<92% identity). We propose that our Bacteroidetes sequences represent two novel subgroups: one at the family level and one at the genus level. The unique ice environment and the high abundance of Bacteroidetes, combined with the coexistence of a high abundance of psychrophilic Chlamydomonas, strongly suggests that there is a viable ecosystem on the surface of Tibetan glaciers. Comparisons of microbial community structures in the five ice samples showed distinct differences, likely due to environmental differences in the locations in which the samples were obtained.