Change of bacterial community in the Malan ice core and its relation to climate and environment

Cryosphere Microbiome Biobanks for Mountain Glaciers in China

The glaciers in China have an important role as one of the most climate-sensitive constituents of the Tibetan Plateau which is known as the Asian Water Tower. Although the cryosphere is one of the most extreme environments for organisms, the soils of the glacier foreland harbor surprisingly rich microbiomes. A large amount of accelerated glacier retreat accompanied by global warming will not only raise the sea level, but it will also lead to the massive release of a considerable amount of carbon stored in these glaciers. The responses of glacier microbiomes could alter the biogeochemical cycle of carbon and have a complex impact on climate change. Thus, understanding present-day and future glacier microbiome changes is crucial to assess the feedback on climate change and the impacts on ecosystems. To this end, we discuss here the diversity and biogeochemical functions of the microbiomes in Chinese mountain glacier ecosystems.

Differences in Bacterial Diversity and Communities Between Glacial Snow and Glacial Soil on the Chongce Ice Cap, West Kunlun Mountains

A detailed understanding of microbial ecology in different supraglacial habitats is important due to the unprecedented speed of glacier retreat. Differences in bacterial diversity and community structure between glacial snow and glacial soil on the Chongce Ice Cap were assessed using 454 pyrosequencing. Based on rarefaction curves, Chao1, ACE, and Shannon indices, we found that bacterial diversity in glacial snow was lower than that in glacial soil. Principal coordinate analysis (PCoA) and heatmap analysis indicated that there were major differences in bacterial communities between glacial snow and glacial soil. Most bacteria were different between the two habitats; however, there were some common bacteria shared between glacial snow and glacial soil. Some rare or functional bacterial resources were also present in the Chongce Ice Cap. These findings provide a preliminary understanding of the shifts in bacterial diversity and communities from glacial snow to glacial soil after the melting and inflow of glacial snow into glacial soil.

Abundance and community of snow bacteria from three glaciers in the Tibetan Plateau

Bacterial abundance and diversity in snow of East Rongbuk, Laohugou and Hailuogou glaciers on the Tibetan Plateau were investigated through epifluorescence microscope and denaturing gradient gel electrophoresis. Cell abundance ranged from 4.0 x 10(3) to 290.2 x 10(3) cells/mL. The phylogenetic trees placed the 16S rRNA sequences in four major groups: Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Brevundimonas, Flavobacterium, Hymenobacter, Bacillus, Polaromonas, Rhodoferax and Streptomyces were widely distributed bacteria in glaciers from different cold regions. The remaining five genera of Hylemonella, Delftia, Zoogloea, Blastococcus and Rhodococcus were endemism, only recovered from our investigated glaciers. It is proposed that the three glaciers on the Tibetan Plateau provide a specific ecological niche for prolonging survival of diverse microbial lineages.

Bacterial community in the East Rongbuk Glacier, Mt. Qomolangma (Everest) by culture and culture-independent methods

The abundance of total and culturable bacteria deposited into the East Rongbuk ice core was investigated, and the bacterial content was examined through culture and culture-independent approaches. Total counts of bacteria in the ice core ranged from 0.02 x 10(3) to 6.4 x 10(3) cells ml(-1). Viable bacteria varied between 0 and 5.6 CFU ml(-1) on PYGV and R2A media. The phylogenetic trees placed the culturable bacteria into four major groups: Actinobacteria, Firmicutes, Proteobacteria and Deinococcus-Thermus, with Firmicutes being the most prevalent. They exhibited unique phenotypic properties with large and non-pigmented cells. The diversity revealed by H' index of DGGE analysis was 0-0.75, and closer sections showed higher similarity of bacterial DNA structure. Members of two major lineages were found: Firmicutes and Proteobacteria. The combined culture and culture-independent methods indicated layer distribution of bacterial community in the ice core section, which might reflect the ecological environments on glacier at time of their deposition.

Bacterial diversity in the snow over Tibetan Plateau Glaciers

Bacterial diversity and cell abundance in the snow of the four glaciers (Guoqu, Zadang, East Rongbuk and Palong No. 4) located in different climatic zones of the Tibetan Plateau were investigated through culture-independent molecular analysis of 16S rRNA gene clone library and flow cytometry approaches. Cell abundance ranged from 0.68 x 10(3) to 720 x 10(3) cells mL(-1), with higher values in the northern glaciers than in the southern ones. Bacterial diversity was unexpectedly high in the snow habitats of the world's highest plateau, with 15 common genera distributed widely among the glaciers. The bacterial diversity in the snow at different glaciers was related to the surrounding environments. The Guoqu Glacier, to the north near the desert zone and with the lowest temperature, preserved more bacteria closely related to a cold environment and soil than the other glaciers. However, in the Palong No. 4 Glacier located in the south warm region around vegetation, most bacteria were phylogenetically related to plant-associated bacteria.

16S rRNA sequences and differences in bacteria isolated from the Muztag Ata glacier at increasing depths

Small subunit 16S rRNA sequences, growth temperatures, and phylogenetic relationships have been established for 129 bacterial isolates recovered under aerobic growth conditions from different regions of a 22-m ice core from the Muztag Ata Mountain glacier on the Pamirs Plateau (China). Only 11% were psychrophiles (grew at 2 degrees C or -2 degrees C up to approximately 20 degrees C), although the majority (82%) were psychrotolerant (grew at 2 degrees C or -2 degrees C up to 37 degrees C). The majority of the isolates had 16S rRNA sequences similar to previously determined sequences, ranging from 85% to 100% identical to database sequences. Based on their 16S rRNA sequences, 42.6% of the isolates were high-G+C (HGC) gram-positive bacteria, 23.3% were gamma-Proteobacteria, 14.7% were alpha-Proteobacteria, 14.7% were Flavobacteria, and 4.7% were low-G+C (LGC) gram-positive bacteria. There were clear differences in the depth distribution, with Proteobacteria, HGC/Cytophaga-Flavobacterium-Bacteroides (CFB), Proteobacteria, LGC/CFB/HGC, Cryobacterium psychrophilum, HGC/CFB, Proteobacteria/HGC/CFB, and HGC/CFB being the predominant isolates from ice that originated from 2.7 to 3.8, 6.2, 7.5, 8.3, 9.0, 9.7, 12.5, and 15.3 m below the surface, respectively. This layered distribution of bacterial isolates presumably reflects both differences in bacteria inhabiting the glacier's surface, differences in bacteria deposited serendipitously on the glacier's surface by wind and snowfall, and nutrient availability within the ice.