Bacteria as Biocontrol Agents for Rearing Larvae of the Crab Portunus trituberculatus

Abstract

Bacterial strain PM-4, isolated from a crustacean culturing pond, improved the growth of crab (Portunus trituberculatus) larvae and repressed the growth of Vibrio anguillarum in seawater. PM-4 was cultured in a large quantity and was added daily for 6 d to 200 m3 of seawater used for culturing crab larvae. Initial bacterial density in the crustacean culture water was 106 cells/mL When bacteria increased to more than 107 cells/mL (at crab larval growth stage zoea II), the protozoan population, primarily flagellates, grew rapidly and reduced bacterial numbers to 106 cells/mL Among the bacterial assemblages monitored, added PM-4 dominated the bacterial populations, i.e. Vibrio spp. numbers decreased or even became undetectable in seawater. Production of crab larvae was greatly increased by adding bacterial strain PM-4 to their culture water.