Judul: Kemampuan isolat tunggal dan campuran dalam mendegradasi senyawa hidrokarbon dari limbah minyak berat
Abstrak: Tumpahan minyak bumi dari kegiatan industri, terutama industri migas, menimbulkan dampak pencemaran yang berbahaya bagi lingkungan. Penanganan limbah minyak bumi ini dapat dilakukan dengan proses bioremediasi dengan bantuan bakteri pendegradasi hidrokarbon. Pada penelitian ini dilakukan pengujian kemampuan isolat bakteri dan penentuan kombinasi isolat terbaik dalam mendegradasi limbah minyak bumi berat. Sebanyak 7 isolat pendegradasi hidrokarbon minyak bumi, dinamakan sebagai MY1, MY3, MY6, MY7, MY8, MY12, dan MYFlr diuji kemampuannya dalam mendegradasi limbah minyak berat (LMB) dalam lima parameter yaitu pertumbuhan bakteri, pH, penurunan TPH padatan dan cairan, dan COD. Semua isolat tumbuh baik pada media yang mengandung 5% LMB pada kisaran 107 – 1010 CFU/ml. Nilai pH media berubah dari 5,0 – 7,0, kecuali MY12 dan MYFlr pada 5,5–8,0. Penurunan TPH berkisar antara 2–65%, dan COD media 2000–80000 ppm. Tiga isolat terbaik yaitu MY7, MY12, dan MYFlr menunjukkan penurunan TPH terbaik selama 28 hari inkubasi, masing-masing sebesar 38,66, 65,42, dan 40,72%. Kombinasi terbaik dari ketiga isolat adalah kombinasi MY7-MY12-MYFlr.
Keyword: Azotobacter, Rhodococcus sp, Pseudomonas sp

Judul: Biodegradasi Limbah Minyak Berat Menggunakan Isolat Tunggal dan Campuran dengan Tambahan Alkilbenzena Sulfonat Linear
Abstrak: Oil spill incident in petroleum industry is inevitability event that caused environmental pollution. Bioremediation is one of the safe methods to handle petroleum polluted environment using bacterial activity. Bacterial were isolated from polluted soil and nourishment by cow and horse manure. The degradation process was improved with linear alkyl benzene sulphonate. The best three isolated microbes and its combination were applied to degrade heavy oil waste combined with linear alkyl benzene sulphonate. The observation parameters were solid Total Petroleum Hydrocarbon (TPH), liquid TPH, Total Plate Count (TPC), Chemical Oxygen Demand (COD), and pH. MY7, MY12, and MYFlr were selected as the best three isolated microbes as shown by their highest percentage of degradation, namely 32.26, 58.25, and 40.74%. The addition of linear alkyl benzene sulphonate proved to augment oil solubility in water, as shown by decreasing solid TPH, increasing liquid TPH, and increasing COD. The value of solid TPH of the three isolate combination in day-21 were 2.33% (w/w), liquid TPH were 1.68% (w/v), and COD were 246456 mg/mL. The degradation level of the three isolate combinations in 21 day-21 was 81.56%. The bacterial combination showed higher degradation level of the waste as compared to that ot the single microbe.
Keyword: 

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology