Bacterial phylotypes associated with the digestive tract of the sea urchin Paracentrotus lividus and the ascidian <Emphasis Type="Italic">Microcosmus</Emphasis> sp. |
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Authors: | A Meziti K Ar Kormas M -A Pancucci-Papadopoulou M Thessalou-Legaki |
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Institution: | (1) Department of Zoology—Marine Biology, School of Biology, University of Athens, 157 84 Panepistimiopoli, Athens, Greece;(2) Department of Ichthyology & Aquatic Environment, School of Agricultural Sciences, University of Thessalia, 383 46 Ionia, Volos, Greece;(3) Institute of Oceanography, Hellenic Centre for Marine Research, PO Box 712, 190 13 Anavissos, Greece |
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Abstract: | We used sequencing and phylogenetic analysis of PCR-amplified 16S rRNA genes from bacteria that are associated with the esophagus/pharynx,
stomach and intestine of two marine sympatric invertebrates but with different feeding mechanisms, namely the sea urchin Paracentrotus
lividus (grazer) and the ascidian Microcomus sp. (suspension feeder). Amplifiable DNA was retrieved from all sections except the pharynx of the ascidian. Based on the
inferred phylogeny of the retrieved sequences, the sea urchin’s esophagus is mainly characterized mostly by bacteria belonging
to α-, γ-Proteobacteria and Bacteriodetes, most probably originating from the surrounding environment. The stomach revealed
phylotypes that belonged to γ- and δ-Proteobacteria, Verrucomicrobia and Fusobacteria. Since the majority of their closest
relatives are anaerobic species and they could be putative symbionts of the P. lividus stomach, in which anaerobic conditions also prevail. Seven out of eight phylotypes found in the sea urchin’s intestine belonged
to sulfate reducing δ-Proteobacteria, and one to γ-Proteobacteria, with possible nutritional activities, i.e. degradation
of complex organic compounds which is beneficial for the animal. The bacterial phylotypes of the ascidian digestive tract
belonged only to the phyla of Actinobacteria and Proteobacteria. The stomach phylotypes of the ascidian were related to pathogenic
bacteria possibly originating from the water column, while the intestine seemed to harbour putative symbiotic bacteria that
are involved in the degradation of nitrogenous and other organic compounds, thus assisting ascidian nutrition.
The text was submitted by the authors in English. |
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Keywords: | Paracentrotus lividus Microcosmus bacteria digestive tract |
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