| Currently, the research of extreme environmental microbial resources has become a global hot spot such as the Antarctic and Arctic. The Arctic Svalbard archipelago, the largest glacier gathering area, has a typical landscapes of Arctic, and also is one of the key areas to study monitor glacier mass balance in the word.In this study, we have collected 5 samples of soil and ice water from the Arctic Svalbard glacier (78 ° 53’N-79 ° 32’N,11 ° 43’E-12 ° 43’E, including glaciers upstream, midstream and downstream). Then we have enriched and separated the general bacteria(63 strains), nitrogen-fixing bacteria(48 strains), denitrifying bacteria(42 strains), nitrobacteria(63 strains), and nitrosobacteria(56 strains). By the methods of 16S rDNA sequences determination and the PCR of functional genes nifH, narG, norB, amoA, the phylogenetic diversities of general bacteria and nitrogen cycle bacteria isolated from the Arctic Svalbard glacier have be researched. In addition to, a suspicious new species S1-10 is found in this study. Then we have identified its true taxonomic positions by the identification methods of morphological, physiological-biochemical, genetic and other phenotypic and genetic characterizations. The aim of this study is to provide the research references of nitrogen-cycle bacteria in other Arctic environmental.Diversity study results showed:(1) The highest count of isolated bacteria was BT sample (the bird activity area of glacier) and the minimum was MS sample (glacier water) of 5 collected samples. But as denitrifying bacteria, the lowest counts of isolated bacteria were AT sample (soil under the glacier) and TN sample (moss mud of glacier). (2)The colony color experiments showed that the colony colors of nitrogen-fixing bacteria was very single, but the colony colors of nitrobacteria, denitrifying bacteria, and nitrosobacteria were variety of colors. (3)The general culturable bacteria(separated by LB medium) isolated from 5 samples were distributed inl8 genera of 7 classes, showing a great 16S rDNA phylogenetic diversities, and in which the dominant bacterial groups were belonged to Pseudomonas genus of Gammaproteobacteria(31.3%). In addition,11 suspected new species were found in the general culturable bacteria isolated from 5 samples. (4) The phylogenetic diversity of nitrogen-fixing bacteria (isolated from no-nitrogen medium) was extremely simple, in which nitrogen-fixing strains were mainly distributed in Pseudomonas genus of Gammaproteobacteria (93.9%). (5) The phylogenetic diversity of denitrifying bacteria strains (isolated by denitrifying medium) was not too rich. These strains mainly belonged to 5 genera of Gammaproteobacteria and Actinobacteriac, and 57.8% of these strains were distributed in Pseudomonas genus of Gammaproteobacteria. (6) The isolated nitrobacteria (separated by nitrobacteria medium) were showed a phylogenetic diversity at some degree, but most of these mainly distributed in 2 genera of Actinobacteriac,3 genera of Alphaproteobacteria,2 genera of Gammaproteobacteria,1 genus of Betaproteobacteria,1 genus of Bacilli. The dominant nitrobacteria groups belonged to Rhodococcus (32.4%) and Arthrobacter (21.6%) in Actinobacteriac. (7) The isolated nitrosobacteria strains (separated by nitrosobacteria medium) exhibited relatively high phylogenetic diversity. These strains mainly distributed in 2 genera of Alphaproteobacteria,2 genera of Gammaproteobacteria,1 genus of Bacilli, and 3 genera of Actinobacteriac, in which the dominant strains were concentrated in Pseudomonas genera of Gammaproteobacteria(37.9%).The polyphasic taxonomy results of suspected new species S1-10 strain isolated from the sea water of Arctic Svalbard glacier downstream showed that the 16S rDNA sequence similarity of S1-10 with its standard strains Aequorivita viscose 8-1bT was 97.60%, DNA-DNA hybridization homology rate of S1-10 and Aequorivita viscose 8-1bT was 33%, and the content G+C% of S1-10 strain was 33.56%(in Aequorivita range). In addition, in the utilization of sole carbon source and nitrogen source, antibiotic resistance, alkali resistance, enzyme and hydrolysis reaction, and other characteristics, there were some differences between S1-10 strains and its standard strain Aequorivita viscose 8-1bT. Therefore, S1-10 strain was determined a new species of the Aequorivita and named Aequorivita beijibingchuans S1-10T。This research is the first diversity study about nitrogen cycle bacteria of Arctic, and the results would not only provide a reference for further similar studies about other ecological environment of the Arctic region, but also can enrich the germplasm resources repository of China and develop the international taxonomic system of nitrogen cycle bacteria. |
PDF Full Text Request