The limiting factor involved in past assessments of soil bacterial diversity when using culture-independent techniques has often been the lack of sampling and replication. As a result, analyses of community structural shifts across soil environments have lacked statistical power. In this study, 23 16S rRNA gene clone libraries consisting of over 11,000 clones were constructed from soils at the Central Arizona Phoenix Long Term Ecological Research (CAP LTER) site. Subsequent ARDRA fingerprinting and partial 16S rRNA gene sequencing allowed for a more robust investigation of various components that may explain any observed variations in bacterial species composition. The designated land use type of the soils best explained the overall diversity gradient. Based on Simpsons reciprocal index, diversity was found to significantly increase when comparing urbanized and agricultural soils to open desert samples located outside the metropolitan region. Land use type appears to be a powerful indicator of overall diversity due to irrigation methods that differ greatly across land use types. Experiment-wise comparisons of complete CAP LTER clone libraries via the LIBSHUFF method yielded no statistical similarity in sequence libraries, except for two replicate libraries constructed from one urban soil. However, inter-phylum LIBSHUFF analysis of the clones also shows degrees of phylogenetic partitioning between land use categories and that open desert remnant patches located within the city limits more closely resemble those urban soils than the open deserts outside of Phoenix. Examination of constructed 16S rRNA phylogenetic trees that include CAP LTER phylotypes indicate some distinct clustering of sequences appears to be driven by land use type rather than geography, and that most of these groups may be endemic to the region. However, some ubiquitous phylotype groups were discovered and were used as templates for specific PCR primer design, allowing for the detection of ten of these groups in all soil samples analyzed. Overall, this study suggests that anthropogenic factors have altered soil bacterial communities, the biogeography of many species is controlled in some manner by land use type, and that a small subset of taxa is ecologically tolerant despite the heterogeneity of habitats within the site.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-11092004-132734 |
| Date | 11 November 2004 |
| Creators | Rash, Brian Anthony |
| Contributors | Kenneth Damann, Meredith Blackwell, Bruce Williamson, Gregg Pettis, Kevin Carman, Fred Rainey |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-11092004-132734/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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