Dutka-Gianelli, J., Kennedy, S.B., Fernandez, E.M., Gensler, A.L., Tucker, J.W., Jr.
Abstract:
Gram negative bacteria, especially Vibrio spp., often are pathogenic to cultured marine fish larvae and their zooplanktonic foods. Probiotic bacteria can be used to decrease gram negative bacteria in the gut, improve health, and increase production of zooplankton. This study assessed effects on the microflora and production rate of rotifers (Brachionus plicatilis) treated with HBOI Bacillus no. 48, which was isolated from healthy cultured common snook (Centropomus undecimalis) larvae.
In two experiments, Bacillus was added to 3-L rotifer cultures daily. Bacteria isolated from the rotifers was cultured on TSA-1% NaCl. Gram staining, 3% KOH test, and morphology were used for preliminary classification of the bacteria.
During 14 days of a continuous culture experiment, seven colony types (five gram positive and two gram negative) were found in control rotifers and five types (all gram positive) in treated rotifers.
In a batch culture experiment (with daily dilution by algae), density of treated rotifers increased from 9.0 to 146.3/ml in 4 days, while control rotifers reached only 50.5/ml.
(Harbor Branch Oceanographic Institution, 5600 North U.S. Highway 1, Fort Pierce, FL 34946, USA)
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