In this study, vegetative cell suspensions of two Bacillus subtilis strains, L10 and G1 in equal proportions,
was administered at two different doses 105 (BM5) and 108 (BM8) CFU ml1 in the rearing water of
shrimp (Litopenaeus vannamei) for eight weeks. Both probiotic groups showed a significant reduction of
ammonia, nitrite and nitrate ions under in vitro and in vivo conditions. In comparison to untreated
control group, final weight, weight gain, specific growth rate (SGR), food conversion ratio (FCR) and
digestive enzymatic activity were significantly greater in the BM5 and BM8 groups. Significant differences
for survival were recorded in the BM8 group as compared to the control. Eight weeks after the start
of experiment, shrimp were challenged with Vibrio harveyi. Statistical analysis revealed significant differences
in shrimp survival between probiotic and control groups. Cumulative mortality of the control
group was 80%, whereas cumulative mortality of the shrimp that had been given probiotics was 36.7%
with MB8 and 50% with MB5. Subsequently, real-time RT-PCR was employed to determine the mRNA
levels of prophenoloxidase (proPO), peroxinectin (PE), lipopolysaccharide- and b-1,3-glucan- binding
protein (LGBP) and serine protein (SP). The expression of all immune-related genes studied was only
significantly up-regulated in the BM5 group compared to the BM8 and control groups. These results
suggest that administration of B. subtilis strains in the rearing water confers beneficial effects for shrimp
aquaculture, considering water quality, growth performance, digestive enzymatic activity, immune
response and disease resistance.
In this study, vegetative cell suspensions of two Bacillus subtilis strains, L10 and G1 in equal proportions,was administered at two different doses 105 (BM5) and 108 (BM8) CFU ml1 in the rearing water ofshrimp (Litopenaeus vannamei) for eight weeks. Both probiotic groups showed a significant reduction ofammonia, nitrite and nitrate ions under in vitro and in vivo conditions. In comparison to untreatedcontrol group, final weight, weight gain, specific growth rate (SGR), food conversion ratio (FCR) anddigestive enzymatic activity were significantly greater in the BM5 and BM8 groups. Significant differencesfor survival were recorded in the BM8 group as compared to the control. Eight weeks after the startof experiment, shrimp were challenged with Vibrio harveyi. Statistical analysis revealed significant differencesin shrimp survival between probiotic and control groups. Cumulative mortality of the controlgroup was 80%, whereas cumulative mortality of the shrimp that had been given probiotics was 36.7%with MB8 and 50% with MB5. Subsequently, real-time RT-PCR was employed to determine the mRNAlevels of prophenoloxidase (proPO), peroxinectin (PE), lipopolysaccharide- and b-1,3-glucan- bindingprotein (LGBP) and serine protein (SP). The expression of all immune-related genes studied was onlysignificantly up-regulated in the BM5 group compared to the BM8 and control groups. These resultssuggest that administration of B. subtilis strains in the rearing water confers beneficial effects for shrimp
aquaculture, considering water quality, growth performance, digestive enzymatic activity, immune
response and disease resistance.
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