Electronic Theses and Dissertation

Abstrak penelitian ini bertujuan untuk mendapatkan isolat bakteri laut potensial penghasil enzim amilase dan menentukan kondisi temperatur dan ph optimum ekstrak kasar enzim amilase dari isolat bakteri laut di perairan selat lembeh, kota bitung, provinsi sulawesi utara. pengujian aktivitas amilase dilakukan dengan menggunakan metode bailey dengan menggunakan reagen asam 3,5-dinitrosalisilat (dns). aktivitas enzim amilase dilakukan berdasarkan uji kualitatif, semi-kuantitatif, dan kuantitatif. uji kualitatif dilakukan dengan pengamatan zona bening yang terbentuk, sementara uji semi-kuantitatif dilakukan dengan mengukur diameter zona bening yang terbentuk. uji kuantitatif dilakukan dengan menggunakan metode dns melalui pengukuran nilai absorbansi ekstrak kasar enzim yang diperoleh. karakterisasi ekstrak kasar enzim amilase dilakukan menggunakan variasi ph dan suhu, dengan rentang ph dari 3,0 hingga 10,0 menggunakan buffer yang berbeda (sodium sitrat, sodium asetat, sodium fosfat, tris-hcl, dan glycine-naoh) dan rentang suhu mulai dari 30 °c hingga 60 °c. pengukuran absorbansi untuk setiap sampel dilakukan pada panjang gelombang 540 nm menggunakan spektrofotometer uv-vis. hasil uji aktivitas amilase menunjukkan bahwa dari sepuluh isolat yang diuji, hanya tiga isolat yang mampu menghasilkan enzim amilase yaitu aa126, aa131, dan aa332. pengukuran zona bening terbesar diperoleh dari isolat aa126 yaitu sebesar 2,29 cm. hasil uji aktivitas enzim amilase dari ketiga isolat aa126, aa131, dan aa332 selama 120 jam waktu produksi terjadi pada 24 jam waktu produksi dengan nilai aktivitas enzim sebesar 0,362 ± 0,020 u/ml. hasil uji tertinggi untuk ekstrak kasar enzim amilase diperoleh dari isolat aa126 yang ditandai dengan ph 5,0 (buffer sodium sitrat) dengan nilai aktivitas enzim sebesar 1,819 ± 0,006 u/ml dan suhu 50 °c dengan nilai aktivitas enzim sebesar 1,209 ± 0,038 u/ml. kata kunci: bakteri laut, enzim amilase, karakteristik, ph, suhu

ABSTRACT This research aims to obtain potential marine bacteria isolates producing amylase enzymes and determine the optimum temperature and pH conditions for crude amylase enzyme extract from marine bacteria isolated in the Lembeh Strait, Bitung City, North Sulawesi. Amylase activity testing was conducted using the Bailey method with 3,5-dinitrosalicylic acid (DNS) as the acid reagent. Amylase enzyme activity was assessed qualitatively, semi-quantitatively, and quantitatively. Qualitative testing involved observing the formation of clear zones, while semi-quantitative testing measured the diameter of the clear zones formed. Quantitative testing was performed using the DNS method by measuring the absorbance values of the obtained crude enzyme extract. Characterization of crude amylase enzyme extract was conducted using variations in pH and temperature, with a pH range from 3.0 to 10.0 using different buffers (sodium citrate, sodium acetate, sodium phosphate, tris-HCl, and glycine-NaOH) and a temperature range from 30 °C to 60 °C. Absorbance measurements for each sample were taken at a wavelength of 540 nm using a UV-Vis spectrophotometer. The results of the amylase activity test indicated that out of the ten tested isolates, only three isolates were able to produce amylase enzymes, named AA126, AA131, and AA332. The largest clear zone measurement was obtained from the AA126 isolate, measuring 2.29 cm. The highest amylase enzyme activity test results for isolates AA126, AA131, and AA332 during the 120-hour production time occurred at 24 hours of production with an enzyme activity value of 0.362 ± 0.020 U/mL. The highest test result for crude amylase enzyme extract was obtained from the AA126 isolate, characterized by pH 5.0 (sodium citrate buffer) with an enzyme activity value of 1.819 ± 0.006 U/mL and a temperature of 50 °C with an enzyme activity value of 1.209 ± 0.038 U/mL. Keywords: Amylase enzyme, Characteristics, Marine bacteria, pH, Temperature