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Identifier 000410314
Title Εδαφική μικροβιακή ποικιλότητα και βλάστηση σε Μεσογειακά οικοσυστήματα
Alternative Title Soil microbe diversity in Mediterranean ecosystems
Author Μπεκρής, Φώτιος Γ.
Thesis advisor Πυρίντσος, Στέργιος
Reviewer Κοτζαμπάσης, Κυριάκος
Πανόπουλος, Νικόλαος
Abstract Background Soil microbes are basic components of terrestrial ecosystems contributing in the decomposition of organic matter and in the recycling of nutrients, having central role in biogeochemical cycles, such as the nitrogen cycle. Despite their central role, the driving forces of their spatial patterns are still widely unknown and it constitutes the basic limitation for their incorporation in management practices of non-cultivated soils. Targets In this thesis a) the study of the relative abundance of ammonia-oxidizing microorganisms (AOA, AOB), b) the study of their genetic diversity patterns, c) the study of genetic diversity of bacteria communities, d) the study of the potential uses of third generation microarrays and e) the study of the phylogenetic relationships of soil microbes are attempted. Methodology Focusing on different NATURA2000 habitat types, the study of soil microbes was based on culture independent techniques, while soil and vegetation data of each habitat type were also collected and incorporated in the analyses. TRFLP analysis was selected as a rapid, sensitive and highly reproducible technique, which is robust for comparative studies. For the TRFLP analysis PCR amplification of the amoA and 16S rRNA genes was performed, while abundances of the amoA gene were determined by real-time PCR. The PhyloChip (G3) of the Affymetrix Inc has been selected for further test. Results According to the results of quantitative PCR, archaeal amoA genes outnumbered and predominated over bacterial amoA genes in ground of all studied areas. The genetic diversity of AOM based on amoA gene, as well as the genetic diversity of soil bacteria communities based on 16S rRNA gene are not differentiated according to the NATURA2000 habitat classification scheme. In several cases, woody plant families in a special relationship with altitude contribute as explanatory factors of the recorded patterns. Although habitat type is not a statistically significant explanatory variable of the genetic diversity patterns, the PhyloChip (G3) can identify groups of bacteria classified according to the habitat type. The phylogenetic analysis of the studied soil microbes revealed their distribution in several clades and valuable phylogenetic information obtained by the PhyloChip (G3). Conclusions Based on the results of the thesis we can conclude among others the following: a) the pattern of AOA dominance in soil of natural ecosystems is a broader trend in the dry areas of Mediterranean Basin, b) several soil factors drive the predominance of AOA, c) despite the limited number of available studies in Mediterranean area, it can be hypothesized that the AOA/AOB values in pastoral landscapes of the Mediterranean Basin compared with the ratio values of other biomes or ecosystems fluctuate at lower levels, d) altitude has both a direct and indirect role in the formation of the studied soil microbes genetic diversity patterns, e) the phylogenetic information retrieved by the use of PhyloChip (G3) has limited contribution in the retrieval of functional and ecological information and f) the selected microarrays could also potentially be used as a tool for monitoring soil microbes in the area at the level of phylum.
Language Greek
Subject Ammnoia monooxygenase
Microbial diversity
Αμμωνιακή μονοοξυγενάση
Issue date 2018-07-13
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Doctoral theses
  Type of Work--Doctoral theses
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