Judul: Potensi streptomyces sp. isolat lokal dalam mendegradasi limbah minyak bumi
Abstrak: Petroleum hydrocarbon pollution of land and water environments has been increasing without proper treatment that can affect stability of ecosystem. One of suitable techniques to solve the crude oil pollution is bioremediation using microbes that can degrade crude oil pollutants to recover the land, water and sediment from contamination. The aim of this research was to screen the capability of indigenous Streptomyces sp. e.g. STR-2, STR-3, B56-2, SLW8-1 and 2075-2K in degrading crude oil pollutants. Degradation processes were assed by growing isolates in International Streptomyces Project 4 (ISP 4) medium supplemented with crude oil, phenol or isooctane as carbon sources. The parameters used were cell biomass, percentage of biodegradation, pH and the changes in crude oil component which was analyzed by Gas Chromatography Mass Spectrophotometry (GCMS) Shimadzu QP2010. The results showed that Streptomyces sp. SLW8-1 had the highest cell biomass during 21 days incubation at room temperature when grown in ISP 4 supplemented with either crude oil (89,60 mg), phenols (92,50 mg) and 14 days incubation in iso-octane (132,80 mg) respectively. The SLW8-1 isolate gave also the highest biodegradation percentage (31%) and decreased the pH during incubation period. The analyzed of carbon structure compounds in non treated crude oil by GCMS when compared with degraded crude oil by the SLW8-1 isolate showed broken from long chain carbon (C20-C27) into short chain carbon (C10-C19). The carbon structures of crude oil was dominated by alcane compounds. The data indicate that SLW8-1 isolate has the ability to degrade crude oil pollutant as carbon source for their growth.
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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.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf