Research Article: In vivo study on probiotic Lactobacillus brevis in Sander lucioperca and some of their nonspecific immune parameters, intestinal morphology and survival against Aeromonas hydrophila

Lactobacillus brevis was isolated from the intestinal tract of Sander lucioperca and its immunological parameters as well as intestinal morphology were studied. Thereafter, the fish were challenged with 4.5×108 CFU/g Aeromonas hydrophila. The fish were monitored daily and the rate of survival was recorded over a period of 7 days post-challenge. The results showed that feeding with supplemented L. brevis (108 to 1010 CFU/g) had significant effect (p<0.05) on the survival rate. The serum lysozyme, alternative complement activity (ACH50) and IgM was significantly enhanced by dietary probiotics during the feeding period and post challenge compared to the control group. The serum IgM levels of dietary supplementation of L. brevis were significantly higher than that of the control after 8 weeks (p<0.05). After 60 days total bacteria and probiotics in the intestinal tract in groups fed with doses of 108 to 1010 CFU/g L. brevis had increased ratio in compare with control sampels. The survival rates after dietary administration of probiotics were significantly higher than that in control in post challenge. The probiotic (1010 CFU g-1) can be used as an effective bio-control agent and as an immune stimulant in aquaculture.