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S, Auch A, Schuster S: Methods for comparative metagenomics. BMC Bioinformatics 2009,10(Suppl 1):S12.PubMedCrossRef Competing interests The author declare that they have no competing interests. Authors’ contributions BS and SJ conceived and designed the experiments. TH, BS and SJ performed the experiments. TH extracted DNA and created the amplicon libraries. BS and TH analyzed the data. BS, TH, SJ, and KJ wrote the manuscript. All authors read and approved the final NVP-LDE225 price manuscript.”
“Background Emerging diseases of marine organisms often manifest in mass mortalities associated with environmental perturbations such as heat stress events [1]. This also applies to marine bivalves where infectious agents cause detrimental effects by profiting from increased temperatures in combination with a weakened

immune response of the host [2, 3]. Prominent

examples for such mass mortalities are ‘summer mortalities’ of farmed and wild Pacific oysters Crassostrea gigas in several localities worldwide [4–6]. Here, the outcome of an infection is thought to be driven by a complex interplay of abiotic factors (e.g., temperature) and biotic factors (e.g., host genetic or immune system effects [7, 8] and/or reproductive state [9]). More recently, host-associated microbiota have also been suggested to play an important role in determining host fitness [10, 11]. Such effects can be mediated by providing additional energy sources by chemosynthesis [12] but also in defence against disease by either preventing establishment of pathogens or directly attacking them with antimicrobial effector molecules isometheptene [13]. The use of probiotics in bivalve aquaculture has therefore been discussed as a means of preventing loss due to disease [14]. However, relatively little is known about microbial communities of native populations and their response to environmental perturbations. Microbial communities residing in different organs of several oyster species have only recently been described by using molecular, culture independent techniques [15–17] that allow intra- and interspecies comparisons [18] and the exploration of environmental factors, such as temperature [19]. For example, oysters invading the Mediterranean from the Indian ocean maintained some of their associated microbes throughout the invasion process [18].