Antagonism And Inhibitory Activities Of Marine Probiotic Strain PB1

Probiotics, which are microorganisms with healthy benefit to the host, have been found to be used in aquaculture as a means of diseases biocontrol.Marine bacterial strain PBl (Altermonas aurantia) was isolated from healthy juvenile black tiger shrimp (Penaeus monodon). It is non-pathogenic bacterium to most of aquacultural animals. The antagonism of PBl was tested by cross-streaking method, agar diffusion assay and BOD in the liquid media. It has a broad spectrum to inhibit tested bacteria including Gram positive and Gram negative strains, especially vibrio. A filamentous bacterium HL-1.(Leucothrix mucor)can be inhibited by PBl also. So strain PBl could be selected as a potential probiotic.A pathogenic strain W-1 (Vibrio anguillarum) was selected as a indicator bacteria to test the inhibitory activities of PBl. the results showed that the compositions of the medium affected the inhibitory activities of the supernatants of strain PBl. The antagonism of the supernatants can be detected when PBl was cultured in monosodium glutamate medium for 3 days. It can not be detected when in marine 2216E broth for 7 days. The concentration of Fe3+ can influence the antibacterial activity of PBl. The siderophore can not be detected from supernatants from iron-limited medium of PBl culture by the unspecific method -CAS assay, while can be detected by the specific chemical method -Casey assay.