Four 96-well plates were used for colony PCR of insert-containing colonies for each composite sample, and all inserts were sequenced regardless of size. This study includes the spectra of those soils plus additional spectra for soils incubated at â1 °C and un-incubated soils. The lowest diversity estimate was obtained from an arctic soil sample that was disturbed by compaction and sampled from a greater depth. Because RSTs can be used for designing phylotype-specific PCR primers (30), more phylogenetic information (a larger portion of the 16S rRNA gene sequence) can be obtained for selected RSTs. Multiple samples were taken from within an area of approximately 20 by 20 meters, with specific sample locations chosen as being representative of the particular boreal forest or arctic tundra sites. For example, measuring the diversity of additional tundra and boreal forest samples, as well as the diversity in lower-latitude samples from tropical regions and regions in the Southern Hemisphere would provide additional insight into this possible biodiversity trend. Russia is experiencing its first anthrax outbreak in more than 70 years. Because the Chao1 diversity estimate uses the relative proportions of singletons and doubletons for calculating estimated diversity, this abundance of rare sequences in tundra soils leads to higher estimates of richness. Another possibility is that the relatively great bacterial diversity of tundra soils may largely reflect allochthonous organisms having low metabolic activity and little functional significance in the soil systems, an example of which is viable mesophilic and thermophilic bacteria isolated from cold soil environments (25, 27). Nucleotide sequence accession numbers.Sequences for DGGE bands A, B, and C were cropped to remove primer sequences and deposited in GenBank with accession numbers AY823417 RST frequency histogram for the six soil composites. Toward overcoming these limitations, serial analysis of ribosomal sequence tags (SARST) was developed for amplification of a highly variable region of the 16S rRNA gene and ligation of these fragments into concatemers that are cloned and sequenced (22, 29, 30). A portion of each composite was sent for physical and chemical analyses to Pacific Soil Analysis (Richmond, British Columbia, Canada). 1B and C). (A) Relative abundance of phylogenetic divisions for each soil library in which RST sequences were assigned to the same taxonomic group as the closest relative in the RDP-II database. 1C and D) and was significantly lesser in the disturbed arctic soil than in all the other soil sample libraries. Strong predominance of individual RSTs indicated a lower evenness of RST distributions and affected the Shannon-Weiner diversity index, in particular. (34) reported decreasing soil functional diversity moving northward along a latitudinal transect through Canadian boreal forest in parts of Saskatchewan and Manitoba. (C) Chao1 richness estimates. In addition, the undisturbed tundra libraries had a higher proportion of rare RST sequences than did the forest, or the Cape Dyer, libraries. Arctic tundra and boreal forest soils have globally relevant functions that affect atmospheric chemistry and climate, yet the bacterial composition and diversity of these soils have received little study. Moss, Fungi, Mushrooms, Lichen, and Bacteria are the main decomposers found in the Tundra. The power of this method is that variable regions from many different organisms are obtained from each sequencing reaction. Analysis of between 1,487 and 2,659 ribosomal sequence tags (RSTs) from each sample, with a total of 12,850 RSTs, provided the basis for robust estimates of phylotype richness and composition. Subsamples were kept at 4°C for transport back to the laboratory and were used immediately or frozen at −80°C. The Bray-Curtis index indicated that the Narrow Hills and Peace River soils had the greatest similarity. A total of 18 25-cycle PCRs were conducted for each composite DNA extract, amplifying the V1 region from the 16S rRNA genes in the DNA extracts. The ePub format uses eBook readers, which have several "ease of reading" features 3A). These sample sizes are too small to adequately describe and compare multiple microbial communities containing thousands of species (19), such as those found in pristine soil and sediment samples (21, 36).
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