Author: Alexis J Berger,   (Nova Southeastern University)

Designation: 

Description:
The pelagic tunicate pyrosome, Pyrosoma atlanticum, is known for its brilliant bioluminescence, but the mechanism causing this bioluminescence has not been fully characterized. Recent studies have suggested that this bioluminescence is due to a novel luciferase, similar to the cnidarian RLuc. Alternatively, this study brings forth information that the cause is due to the presence of bacterial bioluminescent symbionts localized within P. atlanticum light organs. Light and electron microscopy, as well as molecular genetics, were able to identify these symbionts from specimens collected in the northern Gulf of Mexico. Molecular genetics determined that greater than 50% of the bacterial taxa present in the tunicate samples were the bioluminescent symbiotic bacteria Vibrionaceae. After assigning taxonomy to the 396K MiSeq 16S rRNA reads, a Photobacterium sp. r33- like bacterium (which we refer to as “Photobacterium Pa-1”) matched at 99% sequence identity as the most abundant bacteria within Pyrosoma atlanticum samples. Scanning (SEM) and transmission (TEM) electron microscopy confirmed the presence of intracellular rod-like bacteria in the light organs, in addition, specifically designed 16S rRNA V4 probes for fluorescence in situ hybridization (FISH) verified the Photobacterium Pa-1 location as internally concentrated along the periphery of each dual pyrosome luminous organ. The intracellular localization of bacteria may represent bacteriocyte formation reminiscent of other invertebrates.

Category: Scientific Program Abstract > Special Sessions > SS40 Host-microbiome interactions of marine organisms