Application of Bacillus probiotic to prevent Aeromonas hydrophilla infection in Clarias sp.

ABSTRACT The aim of this study was to test the effectiveness of a probiotic Bacillus for the prevention of motile aeromonad septicemia (MAS) disease caused by Aeromonas hydrophila in African catfish (Clarias gariepinus). The study consisted of the inhibition testing of A. hydrophila by Bacillus (in vitro) and the application of probiotic in African catfish (in vivo). The in vivo test, consisted of five treatments such as the addition of probiotic Bacillus P4I1 RifR, Bacillus P4I2 RifR, Bacillus P4I1 RifR + Bacillus P4I2 RifR (Kom), positive control (K+; only added with A. hydrophila) and negative control (K-; without probiotic nor A. hydrophila addition). African catfish (13.35±2.80 g) was maintained in 15 aquariums (40 L in volume) with 30 fishes each for 30 days. Probiotic bacteria was applied in water once a day, whereas pathogenic bacteria A. hydrophila RifR (103 cfu/mL) were added once in earlier treatment (except for the negative control). The result showed that the optimal concentration of Bacillus to inhibit A. hydrophila on in vitro test was 104 cfu/mL. In vivo test showed that the addition of probiotic in media of cultivation could reduce the number of A. hydrophila, improve immune response, and also increase the survival of African catfish compared to positive control. Application of probiotic P4I1 RifR showed the highest survival (92.23%) of all treatments. Keywords: Bacillus, Clarias gariepinus, motile aeromonad septicemia, probiotic ABSTRAK Penelitian ini bertujuan untuk menguji efektivitas probiotik Bacillus dalam pencegahan penyakit motile aeromonad septicaemia (MAS) yang disebabkan oleh Aeromonas hydrophila pada ikan lele dumbo (Clarias gariepinus). Penelitian terdiri atas pengujian penghambatan bakteri probiotik Bacillus terhadap A. hydrophila secara in vitro, dilanjutkan dengan aplikasi pada budidaya ikan lele dumbo (in vivo). Pada uji in vivo, penelitian terdiri atas lima perlakuan yaitu budidaya ikan lele dumbo dengan penambahan probiotik Bacillus P4I1 RifR, Bacillus P4I2 RifR, kombinasi probiotik Bacillus P4I1 RifR + Bacillus P4I2 RifR (Kom), kontrol positif (K+; hanya ditambahkan A. hydrophila) dan kontrol negatif (K-; tanpa pemberian probiotik dan A. hydrophila). Ikan lele dumbo (13,35±2,80 g) dipelihara pada akuarium volume 40 L dengan kepadatan 30 ekor/akuarium selama 30 hari. Bakteri probiotik ditambahkan pada media pemeliharaan ikan setiap hari, sedangkan bakteri patogen A. hydrophila RifR (103 cfu/ mL) diberikan sekali pada awal pemeliharaan (kecuali pada kontrol negatif). Hasil penelitian menunjukkan bahwa konsentrasi terbaik pada penghambatan in vitro adalah dengan penambahan Bacillus 104 cfu/mL. Hasil uji in vivo menunjukkan perlakuan penambahan probiotik pada media budidaya efektif dapat menekan jumlah bakteri A. hydrophila, memperbaiki respons imun, dan meningkatkan kelangsungan hidup ikan lele dumbo dibanding kontrol positif. Perlakuan probiotik P4I1 RifR memberikan hasil terbaik dengan tingkat kelangsungan hidup tertinggi yaitu 92,23%. Kata kunci: Bacillus, Clarias gariepinus, motile aeromonad septicemia, probiotik