Judul: Biodegradation of Polyaromatic Hydrocarbons using Phellinus noxius BRB 11 Isolated from Berbak-Sembilang Biosphere Reserve, Indonesia
Abstrak: Microbial biodegradation of Polyaromatic Hydrocarbons (PAHs) mixture is an eco-friendly practice that requires the exploration of efficient bio-degraders. In this study, three fungal species i.e., Phellinus noxius BRB 11, Leiotrametes menziesii BRB 73, and Ceriporia lacerata BRB 81, were screened out for phenanthrene (PHE) degradation. MnP and laccase of each fungus was analysed using microplate reader while PHE degradation was analysed by gas chromatography. The capability of the selected fungus was then performed in the following four single PAHs treatments i.e., PHE, anthracene (ANT), and Benzo (a)pyrene (BaP), and their mixtures i.e., PHE–ANT, PHE–BaP, ANT–BaP, ANT– PHE–BaP. PHE (100 ppm) final concentration was subjected to only crude laccase enzymes of the selected fungus, and with the addition of 1-Hydroxybenzotriazole (1-HBT), 2,2,6,6-Tetramethylpiperidinyloxy (TEMPO), and Violuric acid (VA) as mediators. These mediators were used in 0.1, 0.3, 0.5, 1, 2, 3, and 4 mM concentration. Toxicity evaluation of degraded and non-degraded PAHs was performed using Vigna radiata and Artemia salina. The results showed that the enzymatic activity was high in BRB 11, and PHE biodegradation results from BRB 11, BRB 73 and BRB 81 i.e. 95%, 24%, and 26%, respectively. Further research was performed using the selected fungus, P. noxius BRB 11. In the single and mixture PAHs degradation experiment, all PAHs except for ANT was degraded above 90%. While BaP was degraded higher than its single degradation. During the degradation, ten metabolites were detected by GCMS and bio-detoxification was observed in all the treated samples. Among mediators used, TEMPO was the most efficient mediator with highest degradation rate on 0.1 mM until 2 mM concentration. PHE degradation was high at 0.1 mM of all mediator concentration, but starts decreasing as 1-HBT and VA mediators approached to higher concentrations. Laccase treated PAH was less toxic to Vigna radiata and Artemia salina than control. This study suggests that Phellinus noxius BRB 11 could be used as a potent PAHs degrader from the environment.
Keyword: Anthracene (ANT), and benzo (a)pyrene (BaP), phenanthren (PHE), degradation, laccase, mediators, Phellinus noxius BRB11, toxicity

Judul: Perubahan Struktur Fenantrena Selama Proses Biodegradasi oleh Bakteri Bacillus altitudinis
Abstrak: Polycyclic aromatic hydrocarbons (PAHs) are toxic, mutagenic, and carcinogenic pollutants that are present in environment. Some bacterial species have ability to metabolize these compounds and use them as energy sources for their growth. Bacillus altitudinis was used to degrade phenanthrene, a three-ring aromatic PAH. The maximum degradation rate (14%) was obtained when Bacillus altitudinis was cultured for 28 days after the addition of 50 ppm phenanthrene to the liquid medium. Furthermore, the degradation was affected by addition of Tween 80 as surfactants. The observation parameters were total plate count (TPC) and pH. The value TPC increased for 28 days cultivation and pH value increased too from 6 to 8 during the 28 days cultivation. The mechanism of degradation was determined through identification of metabolites, the possible pathway of phenanthrene degradation is via phthalic acid. It has been proofed by a mass spectrum of phthalic acid at retention time of 7.607 with match quality of 72.
Keyword: 

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