Bacteria constitute the main group found among the sequences not belonging to the clam. As filter-feeding animals, bivalves can concentrate a large amount of bacteria and it could be one of their sources of food [24] . Because Vibrio spp. are ubiquitous in aquatic ecosystems, it was expected that the Vibrionales order, with 141 hits, would be the most predominant. Several species of the Vibrio genus are among the main causes of disease in bivalves specifically causing bacillary necrosis in larval stages [80] . Is noticeable that sequences belonging to the causative agent of Brown Ring Disease in adults of Manila Clam, Vibrio tapetis, have not been found.