Abstract
Coral reefs are threatened throughout the world. A major factor contributing to their decline is outbreaks and propagation of coral diseases. Due to the complexity of coral-associated microbe communities, little is understood in terms of disease agents, hosts and vectors. It is known that compromised health in corals is correlated with shifts in bacterial assemblages colonizing coral mucus and tissue. However, general disease patterns remain, to a large extent, ambiguous as comparative studies over species, regions, or diseases are scarce. Here, we compare bacterial assemblages of samples from healthy (HH) colonies and such displaying signs of White Plague Disease (WPD) of two different coral species (Pavona duerdeni and Porites lutea) from the same reef in Koh Tao, Thailand, using 16S rRNA gene microarrays. In line with other studies, we found an increase of bacterial diversity in diseased (DD) corals, and a higher abundance of taxa from the families that include known coral pathogens (Alteromonadaceae, Rhodobacteraceae, Vibrionaceae). In our comparative framework analysis, we found differences in microbial assemblages between coral species and coral health states. Notably, patterns of bacterial community structures from HH and DD corals were maintained over species boundaries. Moreover, microbes that differentiated the two coral species did not overlap with microbes that were indicative of HH and DD corals. This suggests that while corals harbor distinct species-specific microbial assemblages, disease-specific bacterial abundance patterns exist that are maintained over coral species boundaries.
Highlights
One of the most recognized features of tropical, shallow-water corals is their symbiosis with photosynthetic unicellular algae that provide photosynthetically fixed carbon to satisfy their host’s respiratory requirements (Muscatine and Cernichiari 1969) and facilitate calcification (Gattuso et al, 1999)
It is being recognized that bacteria contribute significantly to the biology of higher-order organisms (Ezenwa et al, 2012), and bacteria associated with corals are considered a vital component of the coral holobiont
PhyloChip data analysis To visualize similarities within and between species-condition combinations, a multidimensional scaling (MDS) plot based on Bray–Curtis distances of operational taxonomic unit (OTU) abundance data was generated using the DNA extraction Coral samples were crushed to powder in liquid nitrogen using autoclaved mortars and pestles
Summary
Bacterial profiling of White Plague Disease in a comparative coral species framework. We compare bacterial assemblages of samples from healthy (HH) colonies and such displaying signs of White Plague Disease (WPD) of two different coral species (Pavona duerdeni and Porites lutea) from the same reef in Koh Tao, Thailand, using 16S rRNA gene microarrays. Microbes that differentiated the two coral species did not overlap with microbes that were indicative of HH and DD corals This suggests that while corals harbor distinct species-specific microbial assemblages, diseasespecific bacterial abundance patterns exist that are maintained over coral species boundaries. The ISME Journal (2014) 8, 31–39; doi:10.1038/ismej.2013.127; published online 8 August 2013 Subject Category: Microbe-microbe and microbe-host interactions Keywords: 16S rRNA gene microarray; Gulf of Thailand; Pavona duerdeni; Porites lutea; coral disease; White Plague Disease (WPD)
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