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Bacterial Community Structures Associated with Healthy and Diseased Corals from Southern TaiwanChiu, Su-fen 16 June 2010 (has links)
The methods of denaturing gradient gel electrophoresis (DGGE) and DNA sequencing were used to analyze the ribotypes of microbial communities associated with corals. Both healthy and diseased coral of different species were collected at three locations off the southern coast of Taiwan. Ribotyping results suggested that the microbial communities were diverse. The microbial community profiles, even among the same species of corals from different geographical locations or different times, differ significantly. The coral-associated bacterial communities contain many bacteria common to the habitants of various invertebrates. One ribotype presented on the Black Disease coral tissue is closely related to the Clostridium sp. previously identified from White Plaque-diseased and BBD corals. This Clostridium sp. may be relatived to coral diseased, as this species was also found in many types of diseased coral. The other one ribotype presented on our healthy and diseases coral is closed to denitrifying bacterium Pseudovibrio sp. which had been previously discovered in Kenting National Park Nanwan Bay as a new marine, facultative anaerobic bacterium. However, some bacteria were unexpected. The presence of some unusual species, such as Staphylococcus, Legionella and soil bacteria, associated with corals that were likely the results of human activities. Human activities, such as active fishing and tourism industries in the region might have all contributed to the change in bacterial communities and the death of coral colonies around the region.
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Comparative Profiling of coral symbiont communities from the Caribbean, Indo-Pacific, and Arabian SeasArif, Chatchanit 12 1900 (has links)
Coral reef ecosystems are in rapid decline due to global and local
anthropogenic factors. Being among the most diverse ecosystems on Earth, a loss will
decrease species diversity, and remove food source for people along the coast.
The coral together with its symbionts (i.e. Symbiodinium, bacteria, and other
microorganisms) is called the ‘coral holobiont’. The coral host offers its associated
symbionts suitable habitats and nutrients, while Symbiodinium and coral-associated
bacteria provide the host with photosynthates and vital nutrients. Association of corals
with certain types of Symbiodinium and bacteria confer coral stress tolerance, and lack
or loss of these symbionts coincides with diseased or bleached corals. However, a
detailed understanding of the coral holobiont diversity and structure in regard to
diseases and health states or across global scales is missing.
This dissertation addressed coral-associated symbiont diversity, specifically of
Symbiodinium and bacteria, in various coral species from different geographic
locations and different health states. The main aims were (1) to expand the scope of
existing technologies, (2) to establish a standardized framework to facilitate
comparison of symbiont assemblages over coral species and sites, (3) to assess
Symbiodinium diversity in the Arabian Seas, and (4) to elucidate whether coral health
states have conserved bacterial footprints.
In summary, a next generation sequencing pipeline for Symbiodinium diversity
typing of the ITS2 marker is developed and applied to describe Symbiodinium
diversity in corals around the Arabian Peninsula. The data show that corals in the
Arabian Seas are dominated by a single Symbiodinium type, but harbor a rich variety
of types in low abundant. Further, association with different Symbiodinium types is
structured according to geographic locations. In addition, the application of 16S rRNA gene microarrays to investigate how differences in microbiome structure relate
to differences in health and disease demonstrate that coral species share common
microbial footprints in phenotypically similar diseases that are conserved between
regional seas. Moreover, corals harbor bacteria that are species-specific and distinct
from the diseased microbial footprints. The existence of conserved coral disease
microbiomes allows for cataloging diseases based on bacterial assemblage over coral
species boundaries and will greatly facilitate future comparative analyses.
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