The use of baker’s yeast (Saccharomyces cereviciae) as immunostimulant to enhance resistance of nile tilapia (Oreochromis niloticus) to Aeromonas hydrophila
Authors: Manurung Usy N , Manoppo Henky , Tumbol Reiny A 
Published: September 2019

The objective of this research was to evaluate the efficacy of Baker’s Yeast S. cereviciae in enhancing the resistance of nile tilapia (Oreochromis niloticus) to A. hydrophila. As many as 250 fish with an average weight of 28.78±2.44 g were obtained from Fish Culture Development and Training Center of Tateli. After acclimatization, the fish were fed pellet supplemented with Baker’s Yeast as treatments at five different doses, A=0 gr/kg feed, B=5 gr/kg feed, C=10 gr/kg feed, D=15 gr/kg feed, and E=20 gr/kg feed each of which was with three replications.  They were fed for four weeks at 5%/BW/day, twice a day at 08.00 and 16.00, respectively. After feeding period, the fish were challenged intraperitoneally with A. hydrophila.  Before injection, a pathogenicity test of bacteria A. hydrophila was conducted for LD50. Challenged test was carried out by injecting fish with 0.2 ml of bacterial suspension containing 5 x 106 cfu/ml. The fish resistance was observed for 14 days. Dead fish were taken out and bacterial isolation was performed to confirm the cause of the dead.  Results showed that supplementation of Baker’s Yeast into fish pellet had significant effect  on the fish resistance (p=0.00).  The highest resistance (66.6%) was recorded in fish fed with pellet supplement of 5 g Baker’s Yeast per kg of pellet while control fish was only 50%.  As conclusion, supplementation of Baker,s Yeast into fish pellet could enhance resistance of fish to the pathogen. Penelitian ini bertujuan untuk menguji efikasi ragi roti S. cereviciae dalam meningkatkan resistensi ikan nila (Oreochromis niloticus)terhadap bakteri patogen A. Hydrophila. Sebanyak 250 ekor ikan nila dengan berat awal rata-rata 28,78±2,44 g yang diambil dari Balai Pengembangan dan Pembinaan Pembudidayaan Ikan (BP3I) Tateli. Setelah aklimatisasi, ikan diberi ragi roti sebagai perlakuan dengan lima dosis berbeda dan masing-masing perlakuan memiliki tiga ulangan.Perlakuan ragi roti yang digunakan adalah A=0 gr/kg pakan, B=5 gr/kg pakan, C=10 gr/kg pakan, D=15 gr/kg pakan, E=20 gr/kg pakan. Lama pemberian pakan perlakuan empat minggu dengan dosis 5%/bb/hari dan diberikan 2 kali sehari yaitu Pukul 08.00 dan Pukul 16.00. Setelah diberikan ragi roti selama empat minggu ikan diuji tantang dengan bakteri A. Hidrophyla secara Intraperopeneal (ip). Sebelum penyuntikan, dilakukan uji patogenitas bakteri yang memberikan tingkat kematian 50% (LD50). Uji tantang dilakukan dengan cara menyuntikkan 0,2 ml suspensi bakteri pada kepadatan 5 x 106 cfu/ml (sesuai hasil uji patogenitas) pada rongga tubuh ikan. Pengamatan resistensi ikan akan dilakukan setiap hari selama 14 hari. Ikan mati dikeluarkan dan dilakukan isolasi bakteri untuk mengkonfirmasi penyebab kematian ikan. Hasil penelitian mendapatkan bahwa pemberian ragi roti berpengaruh sangat nyata (P=0,00) pada resistensi ikan terhadap bakteri A. Hydrophila. Resistensi tertinggi dicapai pada ikan yang diberi perlakuan B (5 g/kg pakan) dengan tingkat resistensi mencapai 66,6%. Sedangkan ikan yang tidak diberi perlakuan ragi roti (control) memiliki resistensi 50 %. Sebagai kesimpulan penambahan ragi roti dalam pakan dapat meningkakan resistensi ikan terhadap infeksi pathogen.