Host Phylogeny Determines The Gut Microbial Landscape of Cephalopods
Abstract BackgroundCompared to vertebrate gut microbiomes, little is known about the factors shaping the gut microbiomes in invertebrates, especially in non-insect invertebrates. Class Cephalopoda is the only group in the phylum Mollusca characterized by a closed circulatory system and a well-differentiated digestive system to process their carnivorous diet. Despite their key phylogenetic position for comparative studies as well as their ecological and commercial importances, analyses of the cephalopod gut microbiome are limited. In this study, we characterized the gut microbiota of six species of wild cephalopods by Illumina MiSeq sequencing of 16S rRNA gene amplicons.ResultsEach cephalopod gut consisted of a distinct consortium of microbes. Photobacterium and Mycoplasma were prevalent in all cephalopod hosts and were identified as core taxa. The gut microbial composition reflected host phylogeny. The importance of host phylogeny was supported by a detailed oligotype-level analysis of operational taxonomic units assigned to Photobacterium and Mycoplasma, although Photobacterium typically inhabited multiple hosts, whereas Mycoplasma tended to show host-specific colonization. Further, we showed that class Cephalopoda has a distinct gut microbial community from those of other molluscan groups. The gut microbiota of the phylum Mollusca was determined by host phylogeny, diet, and environment (aquatic vs. terrestrial).ConclusionWe provide the first comparative analysis of cephalopod and mollusk gut microbial communities. The gut microbial community of cephalopods is composed of the distinctive microbes and strongly associated with their phylogeny. The genera Photobacterium and Mycoplasma are core taxa in the cephalopod gut microbiota. Collectively, our findings of this study provide evidence that cephalopod and mollusk gut microbiomes reflect phylogeny, environment, and the diet of the host and these data can be suggested to establish future directions for invertebrate gut microbiome research.