Abstract
Bacterial communities of the respiratory tract interact closely with their host and play an important role in the health of animals.1 Respiratory infections can occur due to opportunistic microorganisms that are normally part of the microbiota of a healthy respiratory tract, but that can flourish under certain conditions.2 De novo infections may also occur following exposure to pathogens, and the sequence of events that follow infection can trigger dysbiosis, that is, shifts in the diversity and taxonomic composition of the microbiome.3 Therefore, the bacterial communities of the respiratory tract may be a good indicator of the health status of an individual, and could be particularly relevant for species for which collecting blood samples is fraught with difficulties.4 In this sense, characterizing the respiratory microbiome of cetacean species and investigating inter-individual differences in the composition could be an important tool to identify the health status of cetaceans.3-5 We collected blow samples from 16 individual blue whales in the Bahía de Loreto National Park, located in the southwestern Gulf of California, Mexico; between February and April of 2016 and 2017. To collect the blow samples we used a Phantom 2® quadracopter drone to which sterile Petri dishes had been attached. Genomic DNA was extracted from the samples using a QiaAMP DNA Mini Kit (Qiagen, USA). We also extracted DNA from environmental and technical controls (sea water, sneeze from the drone operator, and laboratory control). All samples were sequenced over two 2- by 250-bp MiSeq (Illumina). Raw sequences were assembled and quality-filtered with Mothur (v.1.39.5).6 Sequences were classified with the SILVA rRNA sequences database (v.132).7 The phyloseq and microbiome packages in R were used to calculated alpha and beta diversities, as well as Simpson and Shannon diversity index.8 We identified 259,898 sequences (of which 23,585 were unique sequences) that corresponded to 7,826 operational taxonomic units (OTUs). Sample coverages were above 96% in all samples. By plotting the species richness (mean: 563, range: 192 to 1191), we identified differences between individuals. The phylogenetically diverse assemblage of sequences spanned eight identified phylum of bacteria (Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, Proteobacteria, Spirochaetes, Tenericutes, and Verrucomicutes), which were present in at least 50% of the hosts.9 These were considered as the core microbiome of the respiratory tract of the blue whale in the Gulf of California, Mexico. Ours is the first study to characterize the respiratory microbiome of blue whales.
* Presenting author
+ Student presenter
Literature Cited
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