EFFECTS OF FREEZE-DRIED AND SPRAY-DRIED PREPARATIONS OF MILFORD PROBIOTIC BACTERIAL STRAIN OY15 IN PREVENTING BACTERIOSIS AND IMPROVING SURVIVAL OF LARVAE OF THE EASTERN OYSTER Crassostrea virginica

The Milford Laboratory has researched and developed Milford probiotic bacterial strain OY15 (Vibrio alginolyticus), from its culture and isolation from the digestive glands of adult Eastern oysters (Crassostrea virginica), to pilot-scale applications to all life stages of oyster larvae.  Results from larval bioassays have shown that this benign, naturally-occurring bacterium has significant positive effects upon the survival and disease resistance of larvae.  OY15 improves survival of oyster larvae by 20-35% when challenged with a known larval shellfish pathogen (Vibrio corallilyticus) by stimulating hemocyte immune defense functions, specifically phagocytosis and Reactive Oxygen Species (ROS) release, two critical steps in pathogen elimination in shellfish.  

The Milford Laboratory collaborated with Envera LLC through a Cooperative Research and Development Agreement (CRADA), utilizing Envera's specialized expertise in manufacturing and providing beneficial microbial products to the aquaculture industry, to determine if OY15 can be mass-cultured effectively and produced economically in a stable formulation for commercialization and marketing to commercial oyster growers.  Envera was successful in large-scale production of OY15 and provided the Milford Laboratory with stable, freeze-dried and spray-dried bacterial formulations.  In May of 2017, the probiotic team conducted a larval oyster bioassay to determine if the effects of the OY15 preparations were similar to the beneficial probiotic effects of live OY15 bacterial cells in protecting larvae from bacteriosis and improving larval survival through metamorphosis.  These results will provide the insight needed to move forward toward commercialization of Milford Probiotic Strain OY15 and subsequent marketing to commercial shellfish growers in the United States.