A novel screening method for the detection of Pseudoalteromonas shioyasakiensis, an emerging opportunistic pathogen that caused the mass mortality of juvenile Pacific abalone (Haliotis discus hannai) during a record-breaking heat wave

Abstract

A serious disease was recorded in juvenile Pacific abalone in Fujian Province, China in 2018. Although this disease caused no obvious external lesions, affected abalone exhibited bleached pedal epithelial cells and a lack of attachment ability. Bacterial strains were collected and cultured from the mucus of moribund and healthy abalone. A novel method was developed for screening abalone pathogens, based on the important role of mucus in the innate immunity of marine organisms. Using bacterial isolation, sequence analysis, and experimental challenges in vitro and in vivo, we identified the bacterial strains pathogenic to abalone. We verified that abalone mortality rates were high when exposed to Pseudoalteromonas shioyasakiensis strain SDCH87 at high temperatures. This opportunistic pathogen had an outstanding growth ability in mucus, and disrupted first line mucosal immunity in the foot within three days. The unprecedented sea surface temperatures associated with the record-breaking 2018 heatwave in south China may have induced opportunistic pathogenic behavior in P. shioyasakiensis. To our knowledge, this is the first report to show that P. shioyasakiensis is a serious opportunistic pathogen of abalone, or possibly mollusks in general, in the context of a heatwave.

Phylogenomic diversity of Vibrio species and other Gammaproteobacteria isolated from Pacific oysters (Crassostrea gigas) during a summer mortality outbreak

“… Photobacterium damselae , is a potential fish, crustacean, and (for those exposed to it) human pathogen [108]. Pseudoalteromonas shioyasakiensis has been reported as an opportunistic pathogen in juvenile Pacific abalone ( Haliotis discus hannai ) [109]. In contrast, while P.…”

“…Photobacterium damselae, is a potential fish, crustacean, and (for those exposed to it) human pathogen [108]. Pseudoalteromonas shioyasakiensis has been reported as an opportunistic pathogen in juvenile Pacific abalone (Haliotis discus hannai) [109]. In contrast, while P. piscicida has no known pathogenicity, it is known to form biofilms with antimicrobial capacity and produce several toxin genes [110].…”