Abstract

The research of probiotics for aquatic animals is increasing with the demand for environmental friendly aquaculture. Most attempts to propose probiotic have been undertaken by isolating and selecting strains from saltpan environment. 16S rRNA gene sequencing showed that strain Bacillus sp. Mk22 (accession number: JF794553) was gram positive, had rod shape and was 937 nm in size. The isolated strain that was applied to Penaeus monodon culture under laboratory condition revealed that maximum survival rate was 92.7 ± 1.53%, wet weight was 6.9 ± 0.15 g, production was 378 ± 1.0 g and feed conversion ratio was 0.9 ± 0.03 in experiment-III compared to those of control experiment. The present study also showed that the halophilic (Bacillus sp.) bacterium was able to colonize both the culture in water and shrimp digestive tract. The minimum total bacterial counts (6.0 ± 1.0×10⁵ Cfu ml^-l) and maximum Bacillus counts (5.6 ± 0.75×10⁴ Cfu g^-l) were recorded in experiment-III and not in the control.

Key words: Bacillus sp., polymerase chain reaction, Penaeus monodon, probiotic, Saltpan.