Studies On Effect Of Multispecies Probiotics On Nonspecific Immunity And Resistance To WSSV Of Litopenaeus Vannamei

1,A feeding experiment of 30 days was conducted to investigate the effects of probiotics on non-specific immunity and antiviral ability of Litopenaeus vannamei. In this experiment, shrimps(3.2±0.26g) were fed different diets supplemented with 10⁸CFU/g Bacillus firmus (live) plus 1% Photobacterium damsela (inactivated), 10⁸CFU/g Bacillus firmus (live), or 10⁸CFU/g Bacillus firmus (live) plus 1% Vibrio alginolyticus (inactivated). Controls were fed non-supplemented diet. Each diet was randomly fed to triplicate groups of 60 shrimps reared in aquarium. Shrimps were challenged with white spot syndrome virus (WSSV) after two weeks of feeding experiment. Ten shrimps per group were sampled every 5 days and some humoral immune parameters (superoxide dismutase SOD, acidic phosphatase ACP, alkaline phosphatase AKP, nitric oxide synthase NOS and lysozyme UL) were evaluated. Feeding the bacteria species significantly increased serum SOD, ACP, AKP and NOS compared with controls. Challenge test shows that shrimps fed the probiotics diet exhibited significantly lower cumulative mortality (10.7%, 39.3% and 26.2%, respectively) compared to the control (64.28%). Based on these results, it is suggested that using shrimp intestine probiotics as feed additives can improve the immunity and antiviral capacity of Litopenaeus vannamei.2,In this study, the influence of three Prawn intestinal probiotics, Bacillus firmus, Photobacterium damsela, Vibrio alginolyticus supplementation was investigated on digestive enzyme activities (Pepsin, lipase and amylase) and intestinal flora in Litopenaeus vannamei. All experiments were triplicated and designed in three different administrations of probiotic. In the first group, probiotic B. firmus (live, 1.0×10⁸CFU/mL) and 1% P. damsela (inactivated) was added to basic feed. In the second group, probiotic B. firmus (live, 1.0×10⁸CFU/mL) was supplemented directly to basic feed. In the third group, probiotic B. firmus (live, 1.0×10⁸CFU/mL) and 1% V. alginolyticus (inactivated) was added to basic feed. Also, noprobiotic treatment was maintained in control group. Mean digestive enzyme activities of all probiotics treatment groups were significantly different (P<0.05) with that of the control. Besides, total bacterial counts and advantage bacterial counts among probiotic supplemented groups were different from that in control. The first group demonstrated the highest amylase activity; the third group demonstrated the highest lipase and pepsin activity; the second group demonstrated the largest number of total bacterial counts and advantage bacterial counts .As a result, supplementation of probiotics to basic feed could significantly increase digestive enzyme activities and therefore, administration of probiotics by this method could improve prawn intestinal flora. The multispecies probiotics have better effect.3,The mRNA relative expression level of thprophenoloxidase (proPO), superoxide dismutase (SOD) and STAT mRNA transcription of L. Vannamei were studied. In this experiment, shrimps(3.2±0.26g) were fed different diets supplemented with 10⁸CFU/g Bacillus firmus (live) plus 1% Photobacterium damsela (inactivated), 10⁸CFU/g Bacillus firmus (live), or 10⁸CFU/g Bacillus firmus(live) plus 1% Vibrio alginolyticus (inactivated). Controls were fed non-supplemented diet. Each diet was randomly fed to triplicate groups of 60 shrimps reared in aquarium. Real-time PCR was proceeded in Rotor Gene 3000 and data was analysed in 2^-Δ,ΔCT method for each gene mRNA relative expression level. The results indicated that proPO mRNA transcription slightly increased. However, no significant differences in SOD and STAT mRNA expression of shrimp were observed among the different treatments. It was concluded that administration of probiotics in the diet could not induce immune modulation of L. vannamei.4,The effect of four shrimp environment symbiotic bacteria on the nonspecific immunity activity (phenoloxidase (PO) activity, superoxide dismutase (SOD) activity, alkaline phosphatase activity (AKP), Nitric oxide synthase activity (NOS) and lysozyme activity(UL) activity ), as well as resistance to White spot syndrome virus (WSSV) of Litopenaeus vannamei was investigated. All experiments were triplicated and designed in three different administrations of bacteria. In the first group, probiotic Microbacterium spp (live, 1.0×10⁸CFU/mL) was added to basic feed. In the second group, bacteria Bacillus thuringiensis (live, 1.0×10⁸CFU/mL) was supplemented directly to basic feed. In the third group, bacteria Bacillus cereus (live, 1.0×10⁸CFU/mL) and 1% Vibrio alginolyticus (inactivated) was added to basic feed. In the forth group, bacteria Bacillus cereus (live, 1.0×10⁸CFU/mL) was added to basic feed. Also, nobacteria treatment was maintained in control group. Shrimps were challenged with white spot syndrome virus (WSSV) after two weeks of feeding experiment. Ten shrimps per group were sampled every 5 days and some humoral immune parameters (proPO, SOD, AKP, NOS and UL) were evaluated. Feeding the bacteria species did not significantly increase serum proPO, SOD, AKP, NOS and UL with controls. Challenge test shows that shrimps fed the bacteria diet did not exhibit significantly lower cumulative mortality compared to the control. Based on these results, it is suggested that the four bacteria as feed additives used in this experiment could not improve the immunity and antiviral capacity of Litopenaeus vannamei.