The Study Of Microbial Community Diversity And Function Along Glacier Foreland In Ny-Alesund, Arctic

Over the past 100 years, the global temperatures have increased by 0.89?. A consequence of the temperature increase is that glaciers are retreating worldwide. Glacial retreat results in the exposure of new land and provides new habitats for microorganisms, plants and invertebrates. Due to the smaller human disturbance, the new land provides an ideal place for microbial succession in nature. In this study, combination of high throughput sequencing technology and culture method was used for studying of microbial community diversity and functional along the chronosequences of Midtre Lovenbreen (MLB) foreland. The high Arctic glacier Midtre Lovenbreen is near Ny-Alesund, in the West Svalbard archipelago (N 74°81'E 10°35'), Norway. This glacier is the most thoroughly studied in Svalbard, and the chronosequences was established by Hodkinson in 2003 by using photographs and radiocarbon analysis. During the Chinese National Arctic Research Expedition in high Arctic in August,2011, eight samples (M0-M7) were collected along the chronosequences, and these eight sites representing soil ages of 0?13?27?48?71? 111?161andca.1900 years.First,646 bacterial strains were isolated from eight sampling sites. The bacterial strains belonged to the phyla Proteobacteria (45.6%),Bacteroidete (23.8%) and Actinobacteria (30.6%). And these bacteria belonged to 57 genera, the dominant bacteria genera are Flavobacterium-. Pseudomonas and Arthrobacterium. Phospholipid fatty acids (PLFAs) analysis indicated that microbial biomass was changed along the chronosequences.Second, high throughput sequencing method was used to analyze bacterial, archaeal, fungal and viral community succession along the chronosequence of MLB glacier foreland. Our results indicated that bacterial Proteobacteria, Actinobacteria, Acidobacteria, Verrucomicrobia, archaeal Thaumarchaeaota, Euryarchaeota, fungal Ascomycota, Basidiomycota and viral Microviridae were the most abundant microbial taxa in this area. However, unique dominant microorganisms were detected at each site along the chronosequences of high Arctic glacier foreland. Such as, Chemolithotrophic, photosynthetic, psychrophilic, and radiation resistant bacteria accumulated in recently exposed site and some symbiotic bacteria, degradation bacteria contained in the oldest soils. Euryarchaeota were predominantly colonizing young soils and Thaumarchaeota mainly mature soils. Fungi shifted from an Ascomycota-dominated community in young soils to a more Basidiomycota-dominated community in old soils. A change from circovirus to bacteriophages then to Iridoviridae was also observed along the chronosequences. It suggested that microbial succession occurred in High Arctic glacier foreland. Moreover, the microbial communities observed in this study showed an important change occurred during 13 years after glacier retreat, the proportion of photoautotrophs increased, the unclassified archaea and Basidiomycota decreased and the major viral taxa replaced from circovirus to bacteriophages.Third, metagenome based on high throughput sequencing technology was used for studying the microorganism function of MLB glacier foreland. The results indicated that there are microorganism and genes that involved in C?N? P?S and Fe cycle. For C cycle; the importance of photosynthesis in younger soils of the glacial foreland was indicated by the presence of a significant number of photosynthetic microorganisms and genes, and the abundance of these microorganisms and genes decreased along the chronosequences. Moveover, methanogens and methane-oxidizing bacteria were found in MLB glacier foreland, and the abundance of these microorganisms increased along the chronosequences. Notably, the study found that some genes in this region were involved in the degradation of pollutants, it may relate to the accumulation of pollutants and microbial degradation. For N cycle, the results indicated that the mineralization of organic material was the driver for N cycling in the young soil. And ammonia-oxidizing bacteria (AOB) were the dominating ammonia-oxidation microorganism. Moreover, the results indicated that there exist some genes that involved in P?S and Fe cycle, but have not found distribution rule of these genes in MLB glacier foreland.It is the first time that horizontal gene transfer (HGT) has been discussed in MLB glacier foreland by using High-throughput sequencing technology. The metagenomic data showed that the abundance of genes that related to conjution, transduction and GTA decreased along the chronosequences. We speculated that young soils may have the highest horizontal gene transfer capacity. The high frequency DNA exchange in the initial stages of the glacier chronosequences may promote microorganism evolution and allowing them better adapt to changes in environmental conditions.Forth, polyphasic taxonomic approach was used to identify three newly recovered bacterial strains R3-20T?R2-4T,R2-35T. Based on phylogenetic, physiological and chemotaxonomic data, three novel species were proposed. Until now, the results of strain R2-4Tand R2-35T had been published. Further experiments showed that strain R3-20T is phosphorus accumulating bacteria, the isolate absorbed phosphorus and synthesized Poly P in the aerobic conditions, and synthesized PHB in anaerobic conditions.The whole genome sequence of strain R3-20T was sequenced, and the mechanism of Poly P and PHB metabolism were explorated by combination of genome data and experimental results.