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Diversity of Rhodopirellula genes in coastal sediments
Samudrahalli Govinde Gowda, R.M. (2011). Diversity of Rhodopirellula genes in coastal sediments. MSc Thesis. Max Planck Institute for Marine Microbiology: Bremen. 77 pp.

Thesis info:
    Max Planck Institute for Marine Microbiology (MPIMM), more

Available in Author 
    VLIZ: Non-open access 227037
Document type: Dissertation

Keywords
    Biodiversity; Rhodopirellula Schlesner, Rendsmann, Tindall, Gade, Rabus, Pfeiffer & Hirsch, 2004 [WoRMS]; Marine
Author keywords
    Rhodopirellula

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  • Samudrahalli Govinde Gowda, R.M.

Abstract
    Microorganisms vary in distribution, abundance and diversity, over various taxonomic and spatial scales and the distribution of microbial diversity at continental scales is poorly understood. The diversity and composition of bacterial communities is known to have a direct influence on a wide range of ecosystem processes. The habitat size of the species and distribution of micro-organisms on earth can be known by studying the biogeography of microorganisms. The increasing number of molecular tools to unravel microbial microdiversity has provided access to more genetic information about environmental bacterial populations and communities, which in turn has significantly helped the reemergence of the study of biogeography. Multilocus sequence analysis (MLSA) can be used to reveal the genetic identity of the isolates on the species level and the habitat sizes of the species. Rhodopirellula baltica, an attached-living marine bacterium may also play a significant role in nutrient cycling processes in marine environments by mineralization of marine snow particles, have been intensively studied over the past few years. The genes closely related to Rhodopirellula baltica have been detected in different habitats all over the world. 69 carB sequences obtained from EHA sample were used for phylogenetic analysis and to estimate diversity indices. Species threshold at 94 % produced 21 OTU from clones and in maximum likelihood phylogenetic tree 89 % (17 OTU) of the clones are in the large cluster of Rhodopirellula. In addition, 206 carB sequences of lumped EHA and JBA clone library produced 27 OTU from clones among which 88% (21 OTU) of clones are closely associated with Rhodopirellula. Venn diagram showed that there is sharing of 14 OTU between the clone library and 7 OTU are specific to EHA library and 6 OTU are specific to JBA library. Diversity indices for species richness and evenness also revealed that there is high diversity and homogeneity between the two clone libraries. In addition, total richness estimates (Chao1) and rarefaction curve at 94 % sequence identity showed that sample EHA and JBA contained an equal bacterial richness at a significance level of 0.05.

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