ISOLASI, KARAKTERISASI DAN IDENTIFIKASI BAKTERI ASAM LAKTAT PENGHASIL α & β-GALAKTOSIDASE PRODUK FERMENTASI KULIT BUAH CEMPEDAK [Arthocarpus integer (Thunb.) Merr.] DAN BUNGA TIGARUN [Crataeva nurvala Buch-Ham]

ORRYANI LAMBUI, Prof. Drs. Langkah Sembiring, M.Sc., Ph.D.

2013 | Tesis | S2 Biologi

Bakteri asam laktat (BAL) yang dapat menghasilkan α & β-galaktosidase telah diisolasi dari produk fermentasi kulit buah cempedak (mandai) dan bunga tigarun (jaruk) menggunakan medium MRS dengan metode enrichment dilanjutkan dengan surface spread plate dan dimurnikan dengan metode streak plate. Tahapan isolasi berhasil mengisolasi 73 isolat penghasil asam, kemudian di screening awal berdasarkan karakter kunci BAL, diperoleh 26 isolat BAL dan dikarakterisasi berdasarkan kemampuan menghasilkan α dan β-galaktosidase melalui pengukuran aktivitas enzim dalam menghidrolisis subsrat p-nitrophenyl- α-D-galactopyronoside (pNPG) dan o-nitrophenyl-β-D-galactopyronoside (oNPG). Dua isolat terpilih yaitu OLM_10 memiliki nilai aktivitas α- galaktosidase tertinggi yaitu 5,07 U/ml dan aktivitas β-galaktosidase 0,43 U/ml dan OLJ_25 memiliki nilai aktivitas α-galaktosidase 4,11 U/ml dan & aktivitas β- galaktosidase tertinggi 1,06 U/ml. Berdasarkan karakterisasi terhadap 2 isolat terpilih didapatkan hasil bahwa isolat OLM_10 diidentifikasi sebagai anggota spesies Streptococcus thermophilus dan isolat OLJ_25 sebagai anggota spesies Lactobacillus plantarum.

Lactic acid bacteria (LAB) producing α and β-galactosidase were isolated from fermentation cempedak skin fruit (mandai) and tigarun flower (jaruk) using MRS medium with an enrichment method, followed by surface spread plate and purified by using streak plate method. Isolation of acid producing bacteria obtained 73 isolates which were indicated by clear zone formed and further, screened based on key character of LAB. The screening succeeded that 26 isolates were found to be LAB. Subsequently, the ability of the isolates to produce α and β-galactosidase were determined by measuring the subsrate hydrolyze pnitrophenyl- α-D-galactopyranoside (pNPG) and o-nitrophenyl-β-Dgalactopyranoside (oNPG). Two isolates were selected that OLM_10 has a value of α-galactosidase activity highest 5,07 U/ml and β-galactosidase activity of 0,43 U/ml and OLJ_25 has a value of α-galactosidase activity of 4,11 U/ml and β- galactosidase activity and highest 1,06 U/ml. Identification and characterization of the two isolates shown that the isolated of OLM_10 is belonging to Streptococcus thermophilus and OLJ_25 is belonging to Lactobacillus plantarum. Therefore, that lactic acid bacteria with α and β-galactosidase activity can be obtained from mandai and jaruk.

Kata Kunci : Bakteri Asam Laktat, α-galaktosidase, β-galaktosidase, mandai, jaruk