The effectivity of probiotic containing Bacillus spp. applicated in the rearing of mud crab Scylla tranquebarica larvae to produce crablet

Abstract

Probiotic bacteria in larvae rearing is expected to suppress pathogenic bacteria and improve water quality. The research aimed to determine the effectivity of probiotic bacteria containing Bacillus subtilis and B. licheniformis on larval rearing of purple mud crab Scylla tranquebarica to produce crablet. The larvae were stocked in nine units of conical fiber tank, fed Rotifers, Brachionus plicatilis, and nauplii Artemia sp. The probiotics tested, namely, A). RICA-4, containing the bacterium Bacillus subtilis, B). RICA-5 containing B. licheniformis, C). A combination of probiotics RICA-4 and RICA-5. The administration of each probiotic with a density of 108 CFU g-1 (5 mg L-1) was given to the water media for larvae rearing. The lowest nitrite and Total Organic Matter in the zoea stage were found in treatment B. At the megalopa stage, treatment B's lowest TOM concentration occurred and was significantly different (p<0.05) from treatment C. On the other hand, the highest population of Vibrio spp (5.5x103 CFU mL-1) was obtained in treatment A. In contrast, treatment C had the highest bacteria population (4.8x104 CFU mL-1). On day 19, the megalopa in treatment B was more abundant than in treatments A and C causing crablet production in treatment B (280.5±47.50 ind. tank -1) was significantly higher (p<0.05) than crablet production in treatment C (196.5±29.50 ind. tank -1) and A (161.0±21.00 ind. tank -1). Therefore, improving water quality in treatment B may have an important factor in enhancing crablet production.