Isolasi dan Uji Aktivitas Enzim Β-Galaktosidase Bakteri Asam Laktat (BAL) dari Fermentasi Buah Sirsak (Annona muricata L.)
Authors: Yuniarti Fitri , Hidayati Wahyu , Setiawati Septi , Nabilah Khansa 
Published: June 2022

AbstrakKemampuan bakteri asam laktat (BAL) dalam menghasilkan enzim β-galaktosidase berguna untuk mengatasi masalah pencernaan pada penderita intoleransi laktosa. Buah sirsak (Annona muricata L.) adalah salah satu sumber isolat BAL. Kandungan glukosa pada buah sirsak berguna untuk pertumbuhan BAL, terutama selama proses fermentasi buah sirsak. Penelitian ini bertujuan untuk mendapatkan isolat BAL yang memiliki aktivitas enzim β-galaktosidase yang diisolasi selama proses fermentasi buah sirsak. Aktivitas enzim diuji dengan mengukur kemampuan enzim β-galaktosidase dalam menguraikan laktosa menjadi monosakarida. Penelitian di awali dengan isolasi BAL selama fermentasi buah sirsak dan dilanjutkan dengan karakterisasi BAL secara makroskopis dan mikroskopis.  Pengukuran aktivitas enzim isolat BAL terpilih dilakukan dengan menggunakan Spektrofotometer Visible dengan substrat o-nitrophenyl-β-D-galactopyranoside (ONPG) dan dilanjutkan pengukuran kadar protein dengan metode Bradford. Hasil penelitian menemukan enam isolat BAL. Aktivitas enzim β-galaktosidase tertinggi ditemukan pada isolat SM6, yaitu 0,292 U/mL dan kadar protein 0,8092 mg/mL. Penelitian ini menemukan, buah sirsak merupakan sumber isolat BAL yang potensial menghasilkan enzim β-galaktosidase. Hasil penelitian ini diharapkan dapat menjadi informasi tambahan mengenai bahan alam sumber isolat BAL penghasil enzim β-galaktosidase, untuk dapat dimanfaatkan bagi penderita intoleransi laktosa.Abstract The ability of Lactic Acid Bacteria (LAB) to produce β-galactosidase enzymes is useful for overcoming digestive problems in people with lactose intolerance. Soursop fruit (Annona muricata L.) is a source of LAB isolates, the glucose content in soursop fruit is useful for LAB growth, especially during the fermentation process of soursop fruit. This study aims to obtain LAB isolates that have β-galactosidase enzyme activity isolated during the fermentation process of soursop fruit. Enzyme activity was tested by measuring the ability of the β-galactosidase enzyme to break down lactose into monosaccharides. The research was started with LAB isolation during soursop fruit fermentation and continued with macroscopic and microscopic characterization of LAB. Examination of the enzyme activity of selected LAB isolates was carried out using a visible spectrophotometer with o-nitrophenyl-β-D-galactopyranoside (ONPG) substrate and continued with protein content measurement using the Bradford method. The results of the study found six LAB isolates. The highest activity of -galactosidase enzyme was found in SM6 isolate, which was 0.292 U/mL and protein content was 0.8092 mg/mL. This study showed that soursop fruit is a source of LAB isolates that have the potential to produce β-galactosidase enzymes. The results of this study are expected to provide additional information regarding natural sources of LAB isolates that produce β-galactosidase enzymes, to be used by people with lactose intolerance.