Bacteria-Affecting Cephalopods

Abstract

Bacterial pathogens contribute to obtain an unsuccessful production of cephalopods. An updated overview of the knowledge of these pathogens must be a valuable tool to improve their aquarium maintenance and aquaculture. The present work provides a description of the main bacterial pathogens associated with larval stages of cultured Octopus vulgaris, and juvenile and adults of several cephalopods. Vibrio species, reported with ability to cause vibriosis in aquaculture, are the main bacteria associated with skin lesions in adults. Different species of Pseudomonas and Aeromonas, among others, have also been detected. Furthermore, gram-positive bacteria such as Bacillus have been also described. Among them, V. alginolyticus, V. carchariae, V. parahaemolyticus, V. splendidus and V. lentus have also been isolated from sterile organs or fluids of animals and their potential as invaders proved. However, only V. alginolyticus or V. lentus has the ability to cause lesions, and, in addition, the last one is proved as the causative agent of death in octopuses. Other organs such as eyes of squids are also colonized by Vibrio species or Micrococcus sp., and recently Photobacterium swingsii and Lactococcus garvieae have been reported associated with a retrobulbar lesion in octopus. Rickettsial-like organisms (RLO) are also detected in the gills of the octopus, having a detrimental effect on the respiratory gaseous exchange of the animals. Cultures of octopus paralarvae show a genetically diverse community comparable to those reported previously from other marine hatcheries. Bacteria included in the Splendidus clade is the dominant group in all conditions, except in one of them, where V. alginolyticus, V. proteolyticus or Pseudomonas fluorescens are the main detected groups. Furthermore, Shewanella or Pseudoalteromonas undina have also been identified. All this shows that pathogenic bacteria are frequent microorganisms associated with aquarium maintenance and culture of cephalopods, and special attention on maintaining a well-balanced community of microorganisms should be applied.