| Summary: | Isolation of Lactic Acid Bacteria (LAB) was carried out from gastro intestinaltract of beluga and Persian sturgeon at international sturgeon research instituteand PCR has been used for bacteria Identification.Two species of LAB including Enterococcus seriolicida and Leuconostocmesenteroides were isolated from Gastrointestinal tract (GI) of persian sturgeonin this study and the counts of Leu. mesenteroides (4.63×102 CFU/gr of GI)was significantly higher than other species. Lactobacillus curvatus,Lactococcus raffinolactis, Lactococcus lactis and Streptococcus sp. were alsoisolated from GI of beluga and maximum counts was belonged to Lb. curvatus(4.63×102 CFU/gr of GI) in this species. Dominant species were lyophilizedand adding to the water since start of mix feeding of sturgeon with differentcounts including 2×109, 5×109 and 9×109 CFU/gr of live food, 4 times a day.The results revealed that the maximum and minimum growth rate and protease,amylase, and lipase activity in beluga was gained by using of Lb. curvatus withtotal viable count of 9×10 9 CFU/gr of live food and Leu. mesenteroides withtotal viable count of 9×109 CFU/gr of live food.According to the results of this study, the maximum and minimum growth rateand protease, amylase, and lipase activity in Persian sturgeon was gained byusing of Leu. mesenteroides with total viable count of 2×10 9 CFU/gr of livefood and Lb. curvatus with total viable count of 9×109 CFU/gr of live food.Histological study showed that gastrointestinal development was same duringlarva rearing in control and other treatments but the size of liver was bigger intreatments that received nonspecific LAB in both species.According to the results, positive effects of using dominant specific LABbacteria for larviculture of sturgeon has been proved in this study. PhD Advisors: Abbas Matinfar Counsellors: Mahmoud Bahmani, Kaveh Jafari Khorshidi
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