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: Aplikasi Bakteri Lokal Indonesia dalam Bioremediasi Tanah Terkontaminasi Minyak Berat, Minyak Ringan dan Limbah Oli Bekas
Abstrak: Oil and gas industrial activity has a potency to contaminate soil. One of the waste released by oil and gas industry is oil sludge. Until now, oil sludge is still a major problem in oil and gas industry especially due to its huge amount. This research was aimed to study the effectiveness of Indonesian local bacteria in bioremediation of soil contaminated with heavy oil, light oil and used lubricant at bench scale. This research was begun by cultivation of 15 strains of hydrocarbon degrading bacteria in Luria Bertani (LB) medium. Each of the cultured isolate was left in a few minutes for thawing, then it was transfered to 20 ml LB medium in erlemeyer using ose. Then, the cultures were incubated in a shaker for 24 hour at ambient temperature. The 15 isolates were selected of their potency in degrading heavy oil by visual assay based on the changes in oil condition in the erlemeyer. The best three heavy oil degrading bacteria selected were Bacillus sp ICBB 7859, Bacillus sp. ICBB 9461 and Bacillus sp. ICBB 5071. The three selected isolates were further characterized by hypersensitive response test, growth curves characteristic, haemolysis test, and antagonistm test. In the main experiment, the three isolates were applicated to soil contaminated with heavy oil, light oil and used lubricant as a single or in combination culture. Parameters used to evaluate their effectiveness in the degradation were soil respiration, pH value, and TPH (Total Petroleum Hydrocarbon). The combination of the three isolates (Bacillus sp ICBB 7859, Bacillus sp. ICBB 9461, and Bacillus sp. ICBB 5071) was the most effective treatment for reducing TPH value of all tested materials (heavy oil, light oil and used lubricant) although statistically was not significantly different with other treatment at 5% test level. The TPH values of soil contaminated with heavy oil, light oil and used lubricant were respectively 0,40, 0,70, dan 0,41% at the end incubation period for 9, 6 and 4 weeks. Based on the GOI Environment Ministerial Decree No. 128/2003, the TPH value of the oil contaminated soil have to be reduced below 1%, before being used for other purposes. Although the combination of the three isolates was the best treatment, it can not be applied in the field due to the patogenicity of the two isolates (Bacillus sp. ICBB 9461 and Bacillus sp. ICBB 5071). Only one isolate, Bacillus sp. ICBB 7859, that has been proven as nonpathogenic one and, therefore, can be used for bioremediation of oil contaminated soil in the large scale.
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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