Investigation on possibility of survival and growth enhancing by selected seaweeds from Persian Gulf in post larvae shrimp Litopenaeus vannamei

The use of antibiotics in aquaculture has been limited. Scientifics seeking for natural substitutes to prevent of aquatic animals diseases. Considering seaweeds are rich of nutritions and bioactive compounds, the purpose of this study is: investigation the potential and use possibility of native seaweeds from Persian Gulf in shrimp aquculture industry to improve growth, survival of postlarvae and to resistance against pathogens such as vibriosis. For this propose 7 macroalgae species from Bushehr province coast, inclouding: green algae (C. iyengarii), brown algae (S. angutifolium and S. ilicifolium) and red algae (L. snyderiae, K. alvarezii and G. corticata) were collected and identified. Then seaweed extracts abtained by Water, Ethanol, Methanol and Chloroform solvents by soaking method. In vitro antibacterial activity of extracts against Gr+ bacteria (S. aureus and B. subtilis) and Gr- bacteria (V. harveyi, V. alginolyticus and E. coli) was conducted by Agar diffusion, MIC and MBC methods. Antioxidant activity also by DPPH and EC50 methods was investigated. According to results of these two tests four seaweeds species (S. angutifolium, L. snyderiae, K. alvarezii and G. corticata) were selected for use in shrimp postlarvae (PL22) diets by Bio-Encapsulation (Artemia enrichment). Before of enrichment, toxicity effect of extracts to Artemia nauplii were evaluated by determination of LC50 24 h method. From results of this section Ethanol extracts were selected to bioencapsulation. After encapsulation shrimp postlarvae divided to 12 groups in triplicate, namely: C-, C+, S (200), S (400), S (600), L(200), L(400), L(600), G(300), G(600), K(300) and K(600). During 30 days of reared period C- and C+ use of basal diet and unenriched Artemia, but the other groups use of basal diet and enriched Artemia. Except C-, the shrimps in first day of culture put in 107 cfu/ml v. harveyi suspension for 30 minutes, and after water exchange 10 ml of this dose was added to reared aquaria. After 30 days survival percentage, obtained weight and SGR% were investigated. To evaluate vibrio loading, every 10 days 5 postlarvae were sampled randomly for vibrio count. Results showed that vibrio count in C- was less than the others and in C+ was more than the others. In treatments vibrio count in L(200) was the most and L(600) was the less. Survival rate in C- was the most and after that G(600) with 79.4±6.6% and then S(300) and K(600) were 73.3±7.3% and 70.6±6.6% respectively that were significantly compare the other (P < 0.01). Also the C+ was the less with 33.3±6.6% that difference was significant (P< 0.01). In this study growth parameters of all groups that fed by enriched Artemia were better than C+ (P<0.05). After cultre period 10 shrimp of every aquarium disinfected and reared for 10 days like before treatment. After 10 days the shrimps were challenged by 3×108 cfu/ml V. harveyi and mortality was recorded for 7 days. The all of animals in C- were survive but more than 90% of C+ were dead. And survival in all of treatments were better the C+ (P<0.05). The study showed the ethanol extracts of selected seaweed from Persian Gulf is a good source for growth, Survival and disease control in shrimp larviculture.

Protection of white leg shrimp (Litopenaeus vannamei) against white spot disease virus using oral recombinant bioencapsulated VP28

Aquaculture, is perceived as having the greatest potential to meet the growing demand for aquatic food. Crustaceans form one of the main value added components in aquaculture and among them, shrimp aquaculture is the predominant one. Industrial shrimp fanning, in combination with poor management in shrimp aquaculture, has quickly led to severe pollution in shrimp ponds, thereby creating a suitable environment for development of bacterial and virus diseases. White spot disease is one of the most deadly diseases that are caused heavy loss in all Penaeid shrimps family. In Iran during 2002 to 2004 in the Kuzestan province and in 2005 in Bushehr province, the most ponds and farms infected with white spot and the entire industry was facing threat of closure. Owing to the impact of WSSV infection to shrimp aquaculture, there is an urgent need to develop suitable strategies to protect cultured shrimps and make aquaculture more sustainable. Therefore, this study aimed to examine the possibility of protecting shrimp against white spot syndrome virus using bioencapsulated Anemia with E. coil containing the recombinant protein VP28, designed. Virus genome was extracted from naturally infected Litopenaeus vannamei in the Choebdch farms and VP28 gene by designed primers was amplified, extracted, purified and cloned in E. coli TGI. Protein expression evaluated and inactivated bacteria containing recombinant protein encapsulated in Artemia nauplii. White shrimp post larvae stage 5 were fed for 5 days with recombinant nauplii and twice on days 7 and 25 after feeding with Artemia nauplii were challenged with white spot virus. The results of the first experiment revealed that cumulative mortality percent in the group receiving the bacteria containing recombinant plasmid (pMal + VP28) was %14.44±1.11 and the relative percent survival %80.30±1.51. In this group the mortality rates in the various repetitions varied from the 13.33% to 16.66% and relative percent survival of 77.27% to 81.81%. in the Non-recombinant plasmid group (pMal) Mean percent mortality was% 33.33±3.84 and the Relative Percent Survival %54.54±5.24 and in the group that received bacteria contained no recombinant plasmid the Mean cumulative mortality percent was%48.88 ± 5.87 and Relative Percent Survival%33.33± 8.01.