EVALUATION OF SELECTED MICROBIAL SYMBIONTS FROM GASTROINTESTINAL TRACT OF GIFT TILAPIA (Oreochromis niloticus) AS POTENTIAL PROBIOTICS IN Litopenaeus vannamei (BOONE, 1931)3021
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Date
2019-11
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JAU, JUNAGADH
Abstract
Present study was designed for evaluation of selected microbial symbionts
isolated from gastrointestinal tract of GIFT tilapia (Oreochromis niloticus) as
potential probiotics in Litopenaeus vannamei (Boone, 1931). Total 40 colonies were
isolated from the gastrointestinal tract and on the basis of gram’s staining 15 colonies
were discarded on the basis of colony morphology study and 25 colonies were
purified by quadrant streaking method. Out of 25 different colonies 10 best
performing colonies were selected for further study. All the colonies were screened
for extracellular enzyme production. The zone of hydrolysis was measured and
enzymatic activity index was calculated for different colonies. Colony C5 showed
highest enzymatic index for amylase production (7.5) while colonies C9 and C10
were negative to amylase. Colony C4 showed highest enzymatic index for cellulase
production (5) while colonies C9 and C10 were negative to cellulase. For chitinase
colony C2, C6 and C8 showed highest enzymatic index for chitinase production (6)
while, colonies C9 and C10 were negative to chitinase. Colony C4 and C9 showed
highest enzymatic index for lipase production (7) while colonies C1 and C8 showed
lowest enzymatic activity index (5) to lipase. For protease Colony C9 showed highest
enzymatic index for amylase production (8) while colonies C2 showed lowest (3.6).
The quantitative analysis of protease showed highest protease production by C9
(21.49 µg/ml) while, colony C4 produced (17.698 µg/ml) protease. Molecular
identification of colonies showed that C1 and C3 were found to be homologous with
Bacillus sonorensis, C2, C5, C6 and C7 were found to be homologous with
Pseudomonas, C4 was found to be homologous with Bacillus thuringiensis, C8 was
found to be homologous with Pseudomonas fragi while C9 and C10 were found to be
homologous with Lactobacillus fermentum. Colony C1 Bacillus sonorensis was ii
selected for probiotic in diet of L. vannamei. The culture of B. sonorensis was
lyophilized and added in the shrimp diet @ 0.5gm in 500gm of feed. The feeding trial
was conducted for 60 days. The effect of B. sonorensis was evaluated on SGR, FCR,
PER and GCE. Four treatment groups T1(100% fish meal), T2 (50% fish meal and
50% soybean meal), T3 (25% fish meal and 75% soybean meal supplement) and T4
(100% soybean meal) were without probiotic supplementation while treatments T5
(100% fish meal with probiotic supplement), T6 (50% fish meal and 50% soybean
meal with probiotic supplement), T7 (25% fish meal and 75% soybean meal with
probiotic supplement) and T8 100% (soybean meal with probiotic supplement). The
highest final wet weight gain was observed in T6 (3.62±0.08) and lowest in T4
(2.10±0.06g) treatments (p>0.05).The highest net weight gain was found in treatment
T6 (3.42gm), where as the lowest was found in T4 diet (1.9gm). The highest net
length was observed in T6 (8.4±0.06 cm) and lowest in T3 (6.93±0.03 cm) treatments
(p>0.05). Data for average net length gain of post larvae of L. vannamei fed without
probiotic and with probiotic diets showed highest net length in treatment T6 (6.6 cm),
whereas the lowest was found in T4 diet (5.17 cm). Highest SGR was found in T6 diet
treatment followed by T2, T3, T7, T8, T5, T1 and lowest in T8. Highest FCR was
found in T4 diet treatment followed by T1, T5, T3, T8, T7, T2 and lowest in T6.
Thus, the lowest FCR was observed in T6 (50% FM and 50% SM with probiotic
supplement). No significant difference (p>0.05) was FCR values observed among the
treatment diets. Highest PER was found in T6 diet treatment followed by T2, T7, T8,
T3, T5, T1 and lowest in T4. Highest GCE was found in T6 diet treatment followed
by T2, T3, T8, T7, T5, T1 and lowest in T4. The findings of the above study indicates
that the treatment T6 showed higher growth of post larvae of L. vannamei at the end
of the experiment along with higher value of SGR (2.15 ± 0.19), FCR (0.35 ± 0.01),
PER (7.13±0.11) and GCE (2.85 ± 0.01) for treatment T6 (50% of fish meal and 50%
soybean meal with probiotic supplementation). From the findings of the above study
it can be concluded that the inclusion of B. sonorensis probiotic strain isolated from
gastrointestinal tract of GIFT tilapia in a shrimp feed can help in 50% of fish meal
replacement by soybean meal in diets of shrimps without compromising with growth
and survival of L. vannamei