Vibriosis is the one of the major pathogenic bacterial disease in shrimp aquaculture. Improving the health status of culture organisms using beneficial microbes as probiotic is the better method to control the pathogens. In this present study the Lactobacillus sp AMET1506 (Which shows strongest antagonistic activity against pathogenic bacteria such as, E.coli, V. cholerae, V.parahaemolyticus, Salmonella sp. and Shigella sp) was previously isolated from curd sample. While checking the antibacterial activity of Lactobacillus sp (AMET1506) against V.harveyi maximum inhibition activity was observed. So, the strain was potentially chosen and it was incorporated in shrimp feed by standard method. A total of 400 Penaeus monodon and Litopenaeus vannamei (each 200) shrimps larvae were obtained from a commercial shrimp hatchery located in Marakanam, Kanchipuram District, Tamil Nadu, India. After acclimation of seven days, the average weights of the shrimps were divided into twelve 50 L plastic tanks each containing 25 juvenile shrimps. The experimental tanks were treated with feed supplemented with 10 6 CFU g-1 of Lactobacillus sp (AMET1506), and the control tanks were fed with a control diet. Shrimp in all the groups were fed twice daily at 5.0% of biomass and the water temperature was maintained at 28 ± 1°C. After 30 days of culture, shrimp in all the control and experimental tanks were exposed to V. harveyi (10 5 CFU ml-1) for 10 days. During the experiment, the accumulated mortality of the shrimp and the microbial load in the shrimp and culture water was recorded. Among that, the shrimp P.monodon treated with Lactobacillus sp AMET1506 resulted in 6% final mortality as compared to 80% in the control group and in L.vannamei treated with Lactobacillus sp AMET1506 resulted in 12% final mortality as compared to 100% in the control group. Based on these results, the work has suggested to use this potential strain Lactobacillus sp AMET1506 as a probiotic in shrimp aquaculture feeds to improve the shrimp microbiota (GIT) and also to control the vibriosis in shrimp aquaculture.

Rice, the crop that gives staple food for India, is being severely affected by several diseases and insect pests. Of these "Sheath Blight" (ShB) disease is one of the economically significant disease that gains serious concern. It is one of the most destructive fungal diseases of rice caused by Rhioctonia solani. It recorded a very high yield loss. Biological control is an efficient disease management strategy. Several microorganisms belong to the genera Bacillus, Pseudomonas, Streptomyces etc are used as "Biological Control Agents" (BCAs) for the management of sheath blight disease in rice. In this scenario, the present work has been aimed to isolate antagonistic rhizobacteria from the least explored coastal sand dune ecosystem, characterize their biological control potential for the suppression of ShB pathogen R. solani and evaluate them in vivo. A total of 46 rhizobacterial strains were isolated from the root hairs of sand dune plant samples using Kings B Agar (KBA) medium. The isolated strains were screened for their antagonist activity against R. solani by using dual culture assay on Potato Dextrose Agar (PDA) medium. About 10 strains were found to have higher in vitro antifungal activity against R. solani i.e., they exhibited zone of inhibition around them. These 10 strains were evaluated for their biocontrol potential in suppressing sheath blight disease in rice using detached leaf bits assay. Five marine associated fluorescent pseudomonad strains such as AMET1102, AMET1104, AMET1133, AMET1133 and AMET1140 have noticeably reduced the ShD incidence in rice leaves.