Selection of prospective probiotic bacteria from the intestines of Rabbitfish, Siganus guttatus as a fermenter for fish feed raw materials

Abstract

Rabbitfish is classified as herbivorous fish by utilizing plants as a staple food, so it has the potential to contain microflora in the digestive tract. The study aimed to select bacteria from the intestines of Rabbitfish as probiotic candidates for degradation of feed ingredients. At the beginning of the study, microbial dissolution of the intestines of 10 Rabbitfish measured weight and body length 127 ±20.1 g and 191.4±1.17 cm, healthy and not deformed, obtained from the waters around the island of Salemo, Regency. Pangkep. At this stage, they have successfully isolated 72 isolates. Then make a selection of bacteria based on the activity of extracellular enzymes by testing the hydrolysis ability of starch using Zobel media adding 1% soluble starch, protein hydrolysis using Zobel media adding 1% skim milk, cellulose hydrolysis using Zobel media adding 1% CMC. The ability of the insulator to hydrolyze starch ranges from 0.4 cm; to protein to 2.4 cm; cellulose to 1.5 cm. Based on these results, 10 isolates were selected as probiotic candidates, namely 411; 413; 422; 427; 430; 434; 437; 452 and 455. The next stage of the pathogenicity test of 10 selected isolates. Each isolate with a density of 106 CFU/mL was injected into 5 juveniles of healthy Rabbitfish intramuscularly as much as 0.1 mL. Monitoring is carried out daily for 10 days after infection to evaluate clinical signs of the disease in test fish. The results obtained showed that no symptoms of pain, injury, or death were found, so it was concluded that the bacterial isolate was not pathogenic.