POTENTIAL PROBIOTICS FOR BIOCONTROL OF DISEASES IN OYSTER CULTURE

Aquaculture sustainability is an important key in the wake of fthe declining seafood supply in Malaysia. I think development of aquaculture industry through green technologies can drive the industry forward. However, some of the projects have come under scrutiny by environmentalists. Thus, this industry demands green technologies. I guess Universiti Putra Malaysia (UPM) along with the government agencies are the drivers to make these technologies become reality. Seafood should be viewed as the source of food to meet the ever increasing food demand in the future, said an official of the Asian Pacific Chapter of the World Aquaculture Society at a meeting in Kuala Lumpur recently.

Here I would like to share a study done by a young researcher Murni Karim, from UPM. Currently she is doing her PhD research at the University of Rhode Island, USA. Her interesting research is about biocontrol activity of bacterial against Roseovarius crassostreae. She won 2^nd place in World Aquaculture Conference this year. Congratulations and all the best Mrs. Murni Karim.

Murni Karim, David Rowley, Marta Gómez-Chiarri

Dept. of Fisheries, Animal and Veterinary Science

University of Rhode Island 169 CBLS,

120 Flagg Road,

Kingston, RI 02881, USA

msh_712@yahoo.com

Roseovarius crassostreae is a bacterial pathogen of oysters Crassostrea virginica that is responsible for juvenile or Roseovarius oyster disease (ROD). ROD causes high seasonal mortalities of juvenile C.virginica in the Northeast US. Several Vibrio spp. also have been reported as the cause of mortality in shellfish hatcheries. Increased concern about this problem has led to research for alternative disease prevention methods, including the use of microorganisms such as bacteria as biocontrol agents. The introduction of selected beneficial bacterial isolates for biocontrol of R. crassostreae and vibriosis might eventually replace the current use of antibiotics, which could reduce their ecotoxicological and ill effects on human health.

This study was undertaken to screen and characterize marine bacterial isolates as potential agents to control pathogenic R. crassostreae and V. tubiashii. Screening of 64 isolates from Rhode Island marine organisms using agar-based assay methods led to the isolation of candidates RIO6-95 and S4. Each isolate displayed strong antibiotic effect against pathogens tested. In an oyster challenge model, pretreatment of larval and seed oysters with RIO6-95 and S4 protected against mortality due to challenge with R. crassostreae and V. tubiashii. Oysters were treated with 10² to 10⁶cfu/ml of the test strains 24 to 48 hours prior to exposure of 10⁵ to 10⁶ cfu/ml of the pathogens. The results suggest the potential of marine isolates RI06-95 and S4 bacteria to serve as biocontrol agents to reduce ROD and vibriosis in C. virginica culture.