Molecular characterization of an Endozoicomonas sp.-like associated with mass mortalities of king scallop Pecten maximus L. in the United Kingdom

The king scallop Pecten maximus L. is the fastest growing fishery in the UK and currently the second most valuable. Mass mortality events in scallops have been reported associated with rickettsia-like organisms (RLOs) world-wide, however the causative agents were uncharacterised. In May 2013 and 2014 two mass mortality events affecting king scallops were recorded in the Lyme Bay Marine Protected Area (MPA) South West England. Histopathological examination showed gill epithelial tissue infected with RLO at varying intensity. Ultrastructural examination confirmed the intracellular location in affected epithelial cells. High-throughput sequencing (Illumina MiSeq) and bioinformatic analysis of 2 gill samples identified over 1000 genes with high similarity, ranging from 77-87% identity, to genes of the genus Endozoicomonas.