Judul: Bioremediation Process of Petroleum-Contaminated Coastal Sand using Oil Spill Dispersant (OSD) and Indigenous Bacteria
Abstrak: Oil pollution in coastal areas due to oil spills is an environmental issue that needs a further concern. Several oil spills have been occurring frequently in the worldwide, such as at Malacca strait and the Northern coast of West Java Province. Crude oil contains persistent organic pollutants (POPs) that are difficult to degrade. This study aimed to obtain bacterial strains that could degrade crude oil, through bacterial isolate characterization, and crude oil biodegradation test in a crude oil-enriched microcosm model. Bacterial isolation was carried out by crude oil enrichment in the bacterial, followed by the bacterial purification, characterization, and identification. From the isolated bacteria, two strains were selected with a higher TPH degradation value, namely CYA20 and CYA27. The CYA20 was tolerant to NaCl up to 4%, while the CYA27 could grow up to 12% NaCl concentration. The strain was also tolerant to the pH of 5 – 9 and temperature of 10 – 50 oC. Both strains were observed to utilize POPs, such as phenanthrene and fluorene. Both strains could produce biosurfactants and perform an emulsification activity in paraffin from 0.373-0.533. Based on the phylogenetic analysis, these bacterial strains are identified as Acinetobacter baumannii CYA20 and Bacillus subtilis CYA27, respectively. Therefore, both strains have the potential as biodegradation agents developed in the bioremediation process of crude oil-contaminated environments.
Keyword: Acinetobacter baumannii, Bacillus subtilis, Bioremediasi, Crude oil, Dispersan, Poliaromatik hidrokarbon

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