The marine symbiont Pseudovibrio denitrificans, is effective to control pathogenic Vibrio spp. in shrimp aquaculture

Abstract

In the search for probiotic bacteria from marine environments to control pathogenic Vibrio of cultivable marine species, this study focused on members of the genus Pseudovibrio. Based on its symbiotic features and antibacterial capacity, the genus Pseudovibrio could be used as probiotic to control vibriosis in shrimp culture. Forty-three isolates of Pseudovibrio were isolated from sponges Aplysina gerardogreeni, and in vitro competitive exclusion assays were performed against shrimp pathogenic Vibrio spp. (Vibrio harveyi, Vibrio campbellii, Vibrio vulnificus and two strains of Vibrio parahaemolyticus, one positive to PirA/PirB toxins). The most bioactive isolates (named Ps11, Ps17 and Ps18) against the pathogenic Vibrio spp. were validated by in vivo trials in the laboratory and in shrimp ponds. A significant increase in the survival of larvae and juveniles challenged. Additionally, the trial performed in PL3, which was naturally infected with V. harveyi, strongly indicates the P. denitrificans capabilities to compete and displace pathogenic Vibrio spp. present in shrimp postlarvae cultures enhancing their survival. Two isolates of P. denitrificans, coded as Ps17 and Ps18, were chosen due to the excellent results obtained in vitro and in the challenge tests and were assessed in experimental culture ponds of Penaeus vannamei. Ps17 and Ps18 were applied in the food once/day, during a complete culture cycle. Survival and production performances were significantly improved in ponds treated with Ps17. These results indicate the advantage of using P. denitrificans as probiotic for shrimp production.