The Benefit of a Roseobacter species on the survival of scallop larvae

A marine strain (BS107), identified as a Roseobacter species, was antagonis tic to Vibrio species on agar plates. Results suggested that the inhibitory effect was displayed only in the presence of another bacterium.. Quantific ation of the antibacterial activity showed that 48-hour-coculture supernata nts from BS107 and another bacterial strain (V. anguillarum 408) reached th e highest titers of bacterial inhibition. The antibacterial substance was a lso liberated when supernatants from V. anguillarum 408 were added to pure cultures of the inhibition-productive bacterium. The presence of a proteina ceous molecule may-induce BS107 to display the inhibitory effect. The antib acterial substance was sensitive to trypsin (8000 U/ml) and stable at 100 d egrees C. Cell extracts. of the isolate BS107 (10(6) cells/ml) significantl y enhanced scallop larval survival, thus being beneficial to the rearing pr ocess.