Disturbance induced decoupling between host genetics and composition of the associated microbiome
1 Helmholtz Centre for Polar and Marine Research, Alfred Wegener Institute, Coastal Ecology, Wadden Sea Station Sylt, Hafenstrasse 43, 25992, List/Sylt, Germany
2 Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29205, USA
3 Benthic Ecology Laboratory, IFREMER, DYNECO, BP70, Plouzane 29280, France
4 Laboratory of Aquatic Photobiology and Plankton Ecology, Institute of Ecology, University of Innsbruck, Technikerstrasse 25, Innsbruck 6020, Austria
5 Department of Ecology and Genetcis, Uppsala University, Limnology, Norbyvägen 18D, Uppsala 75236, Sweden
BMC Microbiology 2013, 13:252 doi:10.1186/1471-2180-13-252Published: 9 November 2013
Studies of oyster microbiomes have revealed that a limited number of microbes, including pathogens, can dominate microbial communities in host tissues such as gills and gut. Much of the bacterial diversity however remains underexplored and unexplained, although environmental conditions and host genetics have been implicated. We used 454 next generation 16S rRNA amplicon sequencing of individually tagged PCR reactions to explore the diversity of bacterial communities in gill tissue of the invasive Pacific oyster Crassostrea gigas stemming from genetically differentiated beds under ambient outdoor conditions and after a multifaceted disturbance treatment imposing stress on the host.
While the gill associated microbial communities in oysters were dominated by few abundant taxa (i.e. Sphingomonas, Mycoplasma) the distribution of rare bacterial groups correlated to relatedness between the hosts under ambient conditions. Exposing the host to disturbance broke apart this relationship by removing rare phylotypes thereby reducing overall microbial diversity. Shifts in the microbiome composition in response to stress did not result in a net increase in genera known to contain potentially pathogenic strains.
The decrease in microbial diversity and the disassociation between population genetic structure of the hosts and their associated microbiome suggest that disturbance (i.e. stress) may play a significant role for the assembly of the natural microbiome. Such community shifts may in turn also feed back on the course of disease and the occurrence of mass mortality events in oyster populations.