Sludge oil contains 30%?50% hydrocarbon fractions that comprise saturated fractions, aromatics, resins, andasphaltene. Asphaltene fraction is the most persistent fraction. In this research, the indigenous bacteria that can degradeasphaltene fractions from a sludge oil sample from Balikpapan that was isolated using BHMS medium (Bushnell-HassMineral Salt) with 0.01% (w/v) yeast extract, 2% (w/v) asphaltene extract, and 2% (w/v) sludge oil. The ability of thefour isolates to degrade asphaltene fractions was conducted by the biodegradation asphaltene fractions test using liquidcultures in a BHMS medium with 0.01% (w/v) yeast extract and 2% (w/v) asphaltene extract as a carbon source. Theparameters measured during the process of biodegradation of asphaltene fractions include the quantification of TotalPetroleum Hydrocarbon (g), log total number of bacteria (CFU/ml), and pH. There are four bacteria (isolates 1, 2, 3, and4) that have been characterized to degrade asphaltic fraction and have been identified as Bacillus sp. Lysinibacillusfusiformes, Acinetobacter sp., and Mycobacterium sp., respectively. The results showed that the highest ability todegrade asphaltene fractions is that of Bacillus sp. (isolate 1) and Lysinibacillus fusiformes (Isolate 2), withbiodegradation percentages of asphaltene fractions being 50% and 55%, respectively, and growth rate at the exponentialphase is 7.17x107 CFU/mL.days and 4.21x107 CFU/mL.days, respectively.Isolasi Bakteri Pendegradasi Fraksi Aspaltik dari Lumpur Minyak Bumi. Lumpur minyak bumi mengandung30%-50% fraksi hidrokarbon yang terdiri dari fraksi jenuh, aromatik, resin, dan aspaltik. Fraksi aspaltik merupakanfraksi yang paling sulit didegradasi. Pada penelitian ini, bakteri pendegradasi fraksi aspaltik merupakan bakteriindigenos yang diisolasi dari sampel lumpur minyak bumi di Balikpapan dengan menggunakan media Bushnell-HassMineral Salt (BHMS) dengan 0.01% (b/v) ekstrak ragi, 2% (b/v) ekstrak fraksi aspaltik, dan 2% (b/v) lumpur minyakbumi. Kemampuan isolat mendegradasi fraksi aspaltik diuji menggunakan media BHMS yang ditambahkan 0.01% (b/v)ekstrak ragi dan 2% (b/v) ekstrak fraksi aspaltik sebagai sumber karbon. Selama uji biodegradasi dilakukan pengukuranparameter yaitu Total Petroleum Hydrocarbon (g), jumlah total bakteri (CFU/mL), dan pH. Empat isoat bakteri (isolat1,2,3, dan 4) yang telah dikarakterisasi mampu mendegradasi fraksi aspaltik dan teridentifikasi secara berurutansebagai, Acinetobacter sp., and Mycobacterium sp. Berdasarkan hasil penelitian, Bacillus sp. (isolat 1) danLysinibacillus fusiformes (Isolat 2) memiliki kemampuan terbaik dalam mendegradasi fraksi aspaltik, kemampuanbiodegradasi fraksi aspaltik secara berurutan adalah 50% dan 55%, dan laju pertumbuhan pada fase eksponensial secaraberurutan adalah 7.17x107 CFU/mL.hari dan 4.21x107 CFU/mL.hari. |