Isolasi, seleksi, karakterisasi dan identifikasi bakteri asam laktat penghasil bakteriosin dari berbagai buah masak

SARKONO, Langkah Sembiring, M.Sc.,Ph.D

2005 | Tesis | S2 Biologi

Buah-buahan diduga merupakan salah satu sumber bakteri asam laktat yang baik disebabkan komposisi kimiawi dan kondisi lingkungan mikronya yang mendukung untuk kehidupan bakteri asam laktat. Penelitian ini dilakukan untuk mempelajari keanekaragaman bakteri asam laktat pada berbagai buah masak, memperoleh isolat bakteri asam laktat penghasil bakteriosin potensial, menentukan karakteristik fenotipiknya, mengklasifikasi dan mengidentifikasi isolat-isolat tersebut secara fenetik. Bakteri asam laktat diisolasi secara selektif dari empat macam buah masak yaitu pepaya, pisang, nanas dan salak dengan metode agar tuang selanjutnya dimurnikan dengan metode goresan. Seluruh isolat diseleksi berdasarkan kemampuannya menghambat pertumbuhan beberapa bakteri patogen. Kemampuan untuk memproduksi bakteriosin ditentukan dengan memanaskan medium kultur pada suhu 100oC selama 60 menit dan perlakuan enzim proteolitik (Proteinase K) dalam suhu kamar. Hasil penelitian menunjukkan 12 isolat bakteri asam laktat mampu menghambat pertumbuhan bakteri indikator Staphylococcus aureus FNCC 0047. Dua isolat terbaik (PE6 dan PE9) juga mampu menghambat pertumbuhan beberapa bakteri patogen seperti Eschericia coli FNCC 0091, Bacillus cereus FNCC 0057 dan Salmonella tiphymurium FNCC 0050. Aktivitas medium kultur dari isolat PE6 tetap stabil pada pemanasan 100oC selama 60 menit dan menurun aktivitasnya dengan perlakuan enzim proteolitik (Proteinase K) sehingga diduga merupakan bakteriosin. Berdasarkan analisis fenotipik terhadap 5 isolat terpilih didapatkan hasil bahwa isolat PE6 diidentifikasi sebagai anggota spesies Lactobacillus acidophilus, isolat PE9 dan PI3 sebagai anggota spesies Pediococcus acidilactici, serta isolat NA4 dan PI1 sebagai anggota spesies Pediococcus pentosaceus

Fruits are indicated as a habitat of lactic acid bacteria (LAB) because their chemical composition and micro environtment which needed to their life. The aim of this research was to study the diversity of lactic acid bacteria on some ripe fruits, to obtain lactic acid bacterial isolate which capable to produce bacteriocin, to know their phenothypic characteristic, classify and identify the isolates phenetically. Lactic acid bacteria were isolated from papaya, banana, pineapple and salak by using pour plate method and then purified by using streak plate method. All isolates were screened their potency to inhibit the growth of some pathogenic bacteria. The capacity to produce bacteriocin were determined by heating the cultural medium at 100oC up to 60 minutes and treating with the proteolytic enzyme (Proteinase K) at room temperature. The result of this experiment indicated that cultural medium from twelve isolates able to inhibit the growth of Staphylococcus aureus FNCC 0047. The best two of isolates (PE6 and PE9) also active to some pathogenic bacteria such as Eschericia coli FNCC 0091, Bacillus cereus FNCC 0057 and Salmonella tiphymurium FNCC 0050. The inhibitory compounds produce by the isolate PE6 was found to be heat stable at 100oC for 60 minutes. However the activity was decrased after treatment with proteolytic enzyme. Therefore the substances was indicated to be bacteriocin. Five representative isolates was chosen for further study for identification. Based on their phenotypic characters analysis, the isolate PE6 was identified to be the member of species Lactobacillus acidophilus, isolate PE9 and PI3 were identified to be the member of species Pediococcus acidilactici, while isolate NA4 and PI1 were identified to be the member of species Pediococcus pentosaceus.

Kata Kunci : Isolasi, seleksi, karakterisasi, dan identifikasi bakteri asam laktat penghasil bakteriosin dari berbagai buah masak