Oyster Larval Survival Counts from Probiotic OY15 Experiments

Environmentally-friendly methods for controlling microbial pathogenesis in aquaculture with probiotic bacteria are becoming increasingly preferred over use of chemical means, such as disinfectants or antibiotics. Recent research at the Milford Laboratory has shown that naturally-occurring bacteria isolated from the digestive glands of adult oysters, Crassostrea virginica, may be used as potential probiotic candidates in oyster larviculture. Probiotic candidate selection was based upon the Kirby Bauer Disc Diffusion Method, in which zones of inhibition suggested competitive exclusion of a known shellfish larvae pathogen (B183). In challenge studies, survival of 2-day old oyster larvae supplemented with probiotic candidate OY15 (Vibrio sp.) was similar (p<0.3883) to that of control larvae (no added bacteria), indicating no harmful effects. Further, addition of OY15 to oyster larvae challenged with B183 significantly improved survival (p<0.0141) compared to the pathogen alone. An in vitro study to determine the effects of OY15 or the pathogen B183 upon oyster hemocytes and their immune functions demonstrated immuno-stimulation of oyster hemocytes by OY15 and immune-suppression by B183, suggesting an immuno-modulation mechanism for OY15.

Environmentally-friendly methods for controlling microbial pathogenesis in aquaculture with probiotic bacteria are becoming increasingly preferred over use of chemical means, such as disinfectants or antibiotics. Recent research at the Milford Laboratory has shown that naturally-occurring bacteria isolated from the digestive glands of adult oysters, Crassostrea virginica, may be used as potential probiotic candidates in oyster larviculture.

ISOLATION AND EVALUATION OF NEW PROBIOTIC BACTERIA FOR USE IN SHELLFISH HATCHERIES: I. ISOLATION AND SCREENING FOR BIOACTIVITY. H. J. LIM, D. KAPAREIKO, E. J. SCHOTT, A. HANIF AND G. H. WIKFORS. Journal of Shellfish Research, Vol. 30, No. 3, 609–615, 2011.

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The Milford laboratory is currently involved in a CRADA (Cooperative Research and Development Agreement) with Envera LLC, to mass-culture Milford probiotic strain OY15 and make freeze-dried or spray-dried formulations. This may cause a constraint on access to the data as intellectual property, until the CRADA has been completed (June 2016) and agreed upon with collaborators.

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Microsoft Excel 2010, Windows 7 Professional, summer 2013 oyster larvae challenges.xls, 33kb

Larval counts are performed on a random 1ml subsample raken from a well-mixed, 250ml concentrated volume of larvae in seawater.

On rare occasion, a count may be missing from the database due to accidental loss of sample.

Data validation during data entry

waiver until the CRADA (Cooperative Research and Development Agreement) has been completed (June 2016) and agreed upon with collaborators.

Regularly-scheduled desktop and network backups for disaster recovery and contingency planning.

Fisher's Island oysters spawned at the Milford Laboratory, and larval bioassays run with 4 treatments: no bacteria control, probiotic OY15, pathogen B183 (Vibrio Corallilyticus) and combination treatment with OY15+B183. Bacteria were dosed every other day and larvae subsamples were taken for survival counts.