Selection of Probiotics for Shrimp and Crab Hatcheries

Celia R. Lavilla-Pitogo, Demy D. Catedral, Sharon Ann G. Pedrajas
and Leobert D. de la Pena


ABSTRACT

A study aimed at obtaining a biological control agent against bacterial diseases, especially luminescent vibriosis, of hatchery-reared shrimps and crabs was done to find an alternative for chemotherapy as a disease prevention and control method. Bacteria were isolated from crustacean rearing environments where luminescent vibriosis was not observed, from natural food, and from various feed ingredients. From hundreds of purified strains, 80 bacterial isolates were tested on one-on-one mixed cultures in seawater for their ability to suppress the growth of luminescent Vibrio harveyi. Of the 10 isolates exhibiting that capability, two strains were further studied: C1 from Chlorella culture and P9 from a commercial probiotic preparation. However, due to the indigenous nature of C1 strain from the unicellular alga Chlorella sp. and ease in distinguishing it from other bacteria owing to its colony morphology, most tests were done on CI strain. To determine the suitability of CI, and to some extent P9, as biocontrol bacteria, their pathogenicity against crab larvae and shrimp postlarvae, and their ability to become associated or incorporated into the larvae were determined. Incorporation into the rotifier, Brachionus, was also tested. Due to positive results obtained in the incorporation experiments, the growth of strain C1 in microbiological media and unrefined media prepared from agricultural by-products was also tested.