Judul: Isolation of deep-sea sediment bacteria for oil spill biodegradation
Abstrak: The potency of deep-sea sediments bacteria is still unfamiliarly used for oil spill biodegradation, and this research was to isolate and identify bacteria from those sediments and adapt them in oily media. Bacterial isolates were cultivated and adapted in a mixture of 0.1% v/v crude oil media. Seven deep-sea sediment samples were treated to isolate bacteria and it produced a variety of bacteria population 5.5 x 102 CFU mL-1 to 1.5 x 106 CFU mL-1. These populations apparently increased after cultivation and adaptation and gave a varying population from 3.0 x 106 CFU mL-1 to 6.8 x 108 CFU mL-1. The increased bacteria population was an indication of the bacterial capability of using carbon in crude oil as a substrate. Those bacteria were Raoultella sp., Enterobacter sp. and Pseudomonas sp., Potensi bakteri sedimen laut dalam untuk teknologi biodegradasi tumpahan minyak masih belum banyak dimanfaatkan. Tujuan dari penelitian ini adalah mengisolasi dan mengidentifikasi bakteri alami dari contoh sedimen laut dalam, dan menyesuaikannya dalam media yang berminyak. Isolat bakteri dikultivasi dan diadaptasi menggunakan media air laut terkondisi nutrien yang dicampur dengan minyak mentah 0.1% v/v. Isolasi dari 7 contoh sedimen laut dalam menghasilkan jumlah populasi bakteri 5.5 x 102 CFU mL-1hingga 1.5 x 106 CFU mL-1. Setelah kultivasi dan adaptasi dilakukan, populasi bakteri meningkat yaitu sebesar 3.0 x 106 CFU mL-1 hingga 6.8 x 108 CFU mL-1. Peningkatan tersebut mengindikasikan bahwa bakteri mampu menggunakan karbon pada minyak mentah sebagai sumber nutrisi. Bakteri yang teridentifikasi dalam penelitian ini diantaranya Raoultella sp., Enterobacter sp. Dan Pseudomonas sp.
Keyword: Bacteria, Biodegradation, Deep-sea Sediment, Isolation, Oil Spill

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