Optimizing media for Bacteriosin Production by Bacillus sp. Strain LTS 40 Isolated from Shrimp Pond.

Abstract

Export demand on shrimp as fishery commodity has increased. However, nowadays Vibriosis diseases caused by fluorescent bacterium Vibrio harveyi have decreased shrimp production. Probiotic bacteria can be used as biocontrol to inhibit the growth of V. harveyi in ponds. Bacillus sp. LTS 40 as a probiotic candidate was able to produce bacteriosin inhibiting the growth of V. harveyi. Production of bacterial probiotics should be low cost using a cheap media. Media production of bacterial probiotics commonly use molase as carbon sources and fertilizers such as NPK, ZA, and urea as a source of nitrogen. The aim of this research was to get the best media composition for growth of Bacillus sp. LTS 40 in producing bacteriosin. Antimicrobial activity test showed that Bacillus sp. LTS 40 could inhibit the growth of V. harveyi with inhibition index of 1,08. Competition assay in liquid culture also showed that Bacillus sp. LTS 40 could inhibit V. harveyi up to 100% at 24 hours, 48 hours, and 72 hours of incubation. Bacillus sp. LTS 40 had a good growth on media composition of 0,2% molase and NPK. In 10 liter fermentor, bacteriosin was produced during exponential phase and optimum production was at 36 hours of incubation with inhibition zone of 15.25 mm. This result showed that Bacillus sp. LTS 40 can be used as probiotics to reduce mortality of shrimp larvae caused by V. harveyi in shrimp cultures. Key words: Bacillus sp., V. harveyi, bacteriosin