These OTUs belong to orders Vibrionales, Bacteroidales, Erysipelotrichales, Clostridiales and Alteromonadales. It is possible that the observation of a shared OTU membership can be explained by other factors other than host-specific
selection. For example, between teleost fish, the colonization and community structure of the microbial gut community appears ABT263 better explained by environmental factors such as food choice or habitat (i.e. salinity) than by host phylogeny [11, 34]. Considering our single sample location, it is currently unclear if the observed core microbiota in Atlantic cod is explained by host-specific selection or driven by shared environmental factors. Interestingly, human microbial gut communities are functionally remarkably similar, selleckchem despite extensive variation in taxonomic composition [7–9]. This functional redundancy may provide support for a ‘founder takes all’ process of colonization, in which a successful colonizer can prevent the subsequent colonization by other, functionally similar strains through high density blocking . Such a stochastic process could lead to the high variation in community composition that we observe among our different specimens. Conclusions Based on the extensive
454 sequencing of a 16S rRNA V3 region amplicon library, we find that the OTU based community diversity estimates of the intestinal microbial community in wild-caught Atlantic cod vary significantly among individuals collected at a single location. This individual level variation suggests that a complex combination of Foretinib factors influences the microbial species distribution in these intestinal communities. Importantly, such variation has gone unobserved in previous studies of natural populations of teleosts whereby
samples of pooled individuals were analyzed Fludarabine supplier [11, 17], which may affect estimates of the number of shared OTUs among hosts. Methods Live Atlantic cod were collected at a single location (N59.871278, W10.587208) using a fish trap in the Oslo fjord, Norway (Additional file 1) and transported to an animal facility approved by the Norwegian Animal Research Authority (NARA, http://oslovet.norecopa.no/dokument.aspx?dokument=67, approval number 155/2008). The specimens were kept in a common tank (2000 l), at ambient water temperature and light conditions (i.e., 6°C and L:D 8:16, respectively) without feed for between seven and twelve days before sampling to help reduce variation in community composition due to the presence of food items . The fish were humanely sacrificed by a blow to the head (without any administration of other sedatives) before sampling. The experiments were approved by NARA’s authorized representative at the facility and were conducted in accordance with the European Convention for the protection of vertebrate animals (http://conventions.coe.int/treaty/en/treaties/html/123.