GRANT
NUMBER: NA96FD0280
REPORT
TITLE:
Probiotics
to Increase Shellfish Hatchery Production
AUTHOR:
Pacific Shellfish Institute
PUBLISH
DATE:
December 2002
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ABSTRACT
The purpose
of the project was to identify and test the approach
of using probiotic bacteria to prevent bacterial diseases
in shellfish hatcheries. The laboratory validation
of the beneficial effect of specific probiotic bacterial
species was the goal of this project and consisted
of three objectives: (1) identify and quantify probiotic
activity of candidate species of bacteria, (2) confirm
identity of the bacterial species and (3) conduct laboratory
tests of probiotic effectiveness to prevent bacterial
disease in shellfish larvae and seed. We characterized
both laboratory archived bacterial strains as well
as 24 new isolates for probiotic activity. Significant
probiotic activity was found. The identity of bacterial
isolates and a portion of the bacterial pathogenicity
testing for the project was performed as a University
of Washington Master’s thesis research project conducted
by Ms. Robyn Estes (Estes 2002). This thesis work consisted
of characterization of 109 bacterial isolates, pathogenicity
testing of a selection of the isolates and phenotypic
and phylogenetic analysis of larval oyster pathogens
and related bacterial cultures. The 16s rDNA of eight
strains of bacteria was cloned and sequenced in order
to evaluate the phylogenetic relationship between these
strains and known and described species of bacteria.
To
complete objective three of the project, three highly
pathogenic isolates were confirmed and selected for
both in vitro and in vivo evaluation and for challenging
larval Pacific oysters and geoduck clams with and
without probiotics. Several of the strong probiotic
producers
were pathogenic to the shellfish larvae and others
exhibited very slow growth rates. Nonetheless, we
identified one probiotic candidate that provided partial
but significant
protection to larval oysters and clams challenged
with pathogenic bacteria. We also isolated additional
useful
strains of non-pathogenic and rapidly growing bacteria
with probiotic activity (in vitro) near the end of
this project but did not have resources to test these
for their ability to protect larval or juvenile shellfish
from bacterial challenge. The results indicate that
successful probiotic candidates must be non-pathogenic
and rapidly proliferating in order to exclude pathogens
from larval cultures.
