ISOLASI DAN IDENTIFIKASI Streptococcus sp. PENYEBAB PENYAKIT PADA NILA MERAH (Oreochromis sp.) DARI KABUPATEN SLEMAN DAN KLATEN

ROSA EIRE REZEKI, Dr.Ir. Murwantoko, M.Si.,

2013 | Skripsi | BUDIDAYA PERIKANAN

Penelitian ini bertujuan untuk mengisolasi, mengidentifikasi Streptococcus sp. penyebab penyakit dan mengetahui patogenisitasnya pada nila merah (Oreochromis sp.). Sampel nila merah berasal dari tiga daerah di Kabupaten Sleman dan Klaten. Bakteri diisolasi dari nila merah dan dilanjutkan uji postulat Koch dengan suntikan intramuskular sebanyak 0,1 ml/ekor dan diamati gejalanya. Karakterisasi dan identifikasi melalui pengujian morfologi sel dan koloni, uji fisiologi dan uji biokimia. Uji patogenisitas dilakukan dengan cara penyuntikan intramuskular pada nila merah ukuran 5-7 cm dengan dosis 104,106,108 cfu/ekor untuk menghitung nilai Lethal Dosage 50 (LD50). Hasil penelitian telah memurnikan 32 isolat bakteri dan diperoleh 25 isolat merupakan Streptococcus sp. Dubelas isolat Streptococcus sp. bersifat patogen, dimana 8 isolat (CK II.1, MK III.2, JT V.1, JT V.2, JT VI, JT VII.2, JT VIII, dan JT IX.2.) teridentifikasi sebagai bakteri S. agalactiae. Empat isolat (CK I.1, MK IV, MK V.2, dan JT V.3) mengarah pada S. iniae. Gejala penyakit yang terserang Streptococcus sp. secara umum adalah pergerakan abnormal dan eksoptalmia. Isolat S. agalactiae (CK II.1, MK III.2 dan JT VI) bersifat virulen terhadap ikan nila dengan LD50 4,36.105; 7,24.106; dan 4,57.105cfu/ekor. S. iniae (CKI.1, MK IV dan JT V.3) bersifat virulen terhadap ikan nila dengan LD50 8,91.106; 7,76.106; dan 7,41.105cfu/ekor.

The objectives of the research were to isolate, to identify Streptococcus sp. and to determine the causative disease of their pathogenicity on tilapia (Oreochromis sp.). The samples were collected from three different areas in Sleman and Klaten Regency. The bacteria were isolated from the samples then continue by postulate Koch test by intramuscular injection at 0,1 ml/fish and observed for it’s symptoms. The characterization and identification were done from morphology of bacterial colony and cell, physiological and biochemical properties. Pathogenicity test were done by injection at the various concentration as 104,106,108cfu/fish into the tilapia with size range of 5 to 7 cm and determined it’s Lethal Dosage value of 50 (LD50). The 32 isolates have been purified and 25 isolates among them were Streptococcus sp .Twelve isolates confirmed as pathogens which divided into 8 isolates (CK II.1, MK III.2, JT V.1, JT V.2, JT VI, JT VII.2, JT VIII, and JT IX.2.) were identified as S. agalactiae and 4 isolates (CK I.1, MK IV, MK V.2, and JT V.3) were identified as S. iniae. The general symptoms of Streptococcus sp. including the abnormal swimming behavior and exophthalmos. The isolate of S. agalactiae (CK II.1, MK III.2 and JT VI) were virulent with the LD50 4,36.105; 7,24.106; and 4,57.105cfu/fish. S. iniae (CKI.1, MK IV, and JT V.3) were virulent with the LD50 8,91.106; 7,76.106; and 7,41.105cfu/fish.

Kata Kunci : Streptococcus, Identifikasi, Nila merah, Patogenisitas