Seleksi bakteri asam laktat dengan laktase tinggi :: Ekstraksi bakteriosin dan pengaruhnya terhadap Staphylococcus aureus

UMAMI, Nafiatul, Ir. Lies Mira Yuliati, SU

2004 | Tesis | S2 Ilmu Peternakan

Penelitian ini bertujuan untuk mendapatkan bakteri asam laktat (BAL) yang mempunyai aktivitas laktase tinggi dan menghasilkan bakteriosin. Feses pedet digunakan sebagai sumber mikrobia untuk mendapatkan isolat BAL. Isolasi pada medium MRS secara anaerobik, suhu 39oC selama 24 jam. Seleksi berdasarkan pada produksi asam laktat, tipe katalase, tipe fermentasi, gram staining dan morfologi sel. Dari isolat yang diperoleh diambil 5 isolat yang mempunyai produksi laktat tertinggi, kemudian diuji aktivitas laktasenya. Selanjutnya isolat yang mempunyai aktivitas laktase tertinggi ditumbuhkan dalam medium susu dengan kadar 100%, 50% dan 25%, diamati produksi laktat, pH serta jumlah koloni yang tumbuh. Data hasil dianalisis dengan analisis variansi pola searah (Complettly Randomized Design) dan dilanjutkan uji DMRT. Kadar susu terbaik untuk pertumbuhan BAL diuji bakteriosinnya dengan metode Turbidimetric assay. Data optical density pada uji bakteriosin diuji dengan regresi non linier. Dari isolasi diperoleh 33 isolat BAL yang mempunyai spesifikasi menghasilkan laktat, katalase negatif, homofermentatif, gram positif dan kokus. Dari 5 isolat penghasil laktat tertinggi didapatkan BAL NWD 015 mempunyai aktivitas laktase tertinggi. Hasil penelitian menunjukkan BAL NWD 015 menghasilkan laktat 41,61%,pH 4,07 dan total mikrobia 1,91X108 pada medium 50% susu (P<0,05). Hasil pengujian bakteriosin menunjukkan bahwa BAL NWD 015 dalam medium MRS dan susu 50% menghasilkan bakteriosin yang dapat memperpanjang fase lag serta menekan pertumbuhan Staphylococcus aureus.

The objective of this study was to isolate lactic acid bacteria (LAB), which has high lactase activity and produces bacteriocin. Feces of young calves as microbe source were used to get LAB using MRS medium anaerobically and incubated at 39oC for 24 hours. The selection include lactic acid production, catalase type, fermentation type, gram staining and cell morphology. Five isolates with high lactic acid production were used for lactase activity test. The highest lactase activity isolate was used as starter in milk fermentation with concentration of milk as much as 100%, 50% and 25%. Lactic acid production, pH and total colony were recorded after 48 hours incubation. The data were analyzed with the analysis variansi pattern Complettly Randomized Design and Duncant New Multiple Range Test. The milk concentration with milk content in medium for the best growth of LAB was used to evaluate bacteriocin production with Turbidimetric assay methode. The data on bacteriocin test were analyzed using non linier regresion test. The 33 isolates were identified as LAB having spesification producing lactic acid, negative catalase, homofermentation, positive gram and cocci in nature. The highest lactase activity isolate was taken out from the 5 most highest lactic acid production isolates namely LAB NWD 015. LAB NWD 015 produced 41.61% lactic acid, pH value of 4.07 and total microbe count of 1.91X108 in medium 50% milk (P<0.05). The bacteriocin extract from MRS and 50% milk medium prolonged log phase and inhibited of Staphylococcus aureus growth.

Kata Kunci : Pakan Ternak,Pencernaan,Ekstraksi Bakteriosin, Lactic acid bacteria, Lactase, Bacteriocin