Screening of Probiotic Bacterium for Controling Streptococcosis in Tilapia Oreochromis niloticus.

Abstract

Streptococcus iniae is a pathogenic bacteria that responsible for streptococcosis disease in tilapia. The used of probiotic bacteria is one of the method in aquaculture that was used to control infectious diseases. The aimed of this research was to find probiotic bacteria from intestine of fresh water fishes and water media potentially inhibit S. iniae infection in tilapia. Eighty six isolates of bacteria that had been isolated from tilapia, common carp, siam catfish, walking catfish and jelawat, as well as from water media, were in vitro and in vivo tested to find out its ability to inhibit S. iniae. Five isolates namely AN3, AL4, WY3 that isolated from tilapia, common carp and catfish intestine respectively, as well as DM1 and KH1 from water media have inhibition activity against S. iniae in vitro and in vivo test. The highest protection of tilapia against S. iniae was showed in fish previously injected with DM1 and AN3. 16SrRNA gene based sequencing of DM1 and AN3 showed that the isolate was Proteus mirabilis and Aeromonas sobria respectively.