title: Diversity of bacteria cultured from the blood of lesser electric rays caught in the northern gulf of Mexico.
abstract: The prevalence and taxonomic diversity of bacteria cultured from the blood of apparently healthy Lesser Electric Rays Narcine bancroftii captured from open beach habitat in the north-central Gulf of Mexico are reported herein. The blood of 9 out of 10 Lesser Electric Rays was positive for bacteria, and bacterial isolates (n = 83) were identified by 16S rRNA gene sequencing. The majority of the isolates belonged to the phylum Proteobacteria (91.5%). Vibrio spp. comprised 53% of all isolates and were recovered from all Lesser Electric Rays with culture-positive blood. Among them, V. harveyi (n = 14) and V. campbellii (n = 11) were most common, followed by a group of unidentified Vibrio sp. (n = 10) related to V. nigripulchritudo. Isolates representing other species of Proteobacteria included Pseudoalteromonas (n = 13), Shewanella (n = 5), Amphritea (n = 3), Nautella (n = 3), and Arenibacter (n = 1). Higher bacterial diversity was observed in blood cultured on marine agar relative to blood agar, but gram-positive bacteria were isolated from the latter only. The 16S rRNA gene sequences of bacterial isolates were compared phylogenetically to those from related type strains. Most isolates were identified to the level of species, but some clustered independently from reference strains, likely representing new species of Vibrio, Amphritea, Shewanella, and Tenacibaculum. The present study is the first record of any bacterium from this ray species and reveals a taxonomically and phylogenetically diverse microbiota associated with its blood. Moreover, these data document that the presence of bacteria in elasmobranch blood is not coincident with clinical signs of disease, thereby rejecting the paradigm of septicemia indicating a disease condition in aquatic vertebrates.
authors.affiliation: a Aquatic Microbiology Laboratory, School of Fisheries, Aquaculture, and Aquatic Sciences , Auburn University , 559 Devall Drive, Auburn , Alabama 36832 , USA.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Tao
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Bullard
authors.forename: Cova R
authors.initials: CR
authors.lastname: Arias
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D060851:Gulf of America; D010802:Phylogeny; D012860:Skates, Fish / Q000097:blood / Q000382:microbiology*