Judul: The Potency of Streptomyces spp. as Biocontrol Agent of Soil Borne Fungi Sclerotium rolfsii through In Vitro and In Planta Assay in Tomato Plant (Solanum lycopersicum).
Abstrak: Selected indigenous isolates of Streptomyces spp. are known as source of antimicrobial compound. The research aims to study the ability of isolates of Streptomyces spp. and their application in suppressing the growth of Sclerotium rolfsii in vitro and in planta assay in tomato plant. Six indigenous Streptomyces spp. isolates which have been isolated from soil rhizhosphere that able to inhibit various soil borne microbial pathogen were chosen against Sclerotium rolfsii in vitro and in planta assay in tomato plants. In vitro assay showed that LSW 05 and PS 4-16 inhibited the growth of Sclerotium rolfsii by 84 and 33% respectively and they were selected for in planta assay. Pouring application of Streptomyces could suppressed the disease level and arised the height of tomato plant, but it not increased percentage of tomato seed germination if it compare to seedcoating application on tomato plant with S. rolfsii addition. LSW 05 isolate could supressed of area under the disease progress curve (AUDPC) until -906. The isolate also increased the height of tomato plant which had the higest value of area under the length progress curve (AULPC) (118) and percentage of tomato seed germination by 70% on S. rolfsii addition. Based on this capability, the LSW 05 isolate is potential to be developed as a biological control agent for soil microbial pathogens in tomato plant. Key words: Streptomyces spp., biocontrol, Sclerotium rolfsii, tomato plant
Keyword: 

Judul: Selection and Characterization of Bacteria Inhibiting the  Growth of Fusarium sp. Derived from the Tomato Plant (Solanum lycopersicum L.).  (Solanum lycopersicum L.).
Abstrak: One of the problems in tomato (Solanum lycopersicum L.) farming is the emergence of wilt disease, which is caused by the fungal pathogen Fusarium sp. Pathogenic fungi have been controlled by spraying synthetic fungicides. The use of fungicides has a negative impact on other organisms and the environment. The negative impact of excessive use of synthetic chemicals can be reduced by using biocontrol agents that produce antifungal compounds. Efforts to control pathogenic fungi naturally using rhizosphere bacteria to control the growth of pathogenic fungi on tomato plants (Solanum lycopersicum L) have not been widely reported. This study aims to select rhizosphere bacteria from 14 bacterial isolates that have been isolated from tomato farming which are able to inhibit the growth of Fusarium sp. in vitro and characterize selected bacteria. The results of the bacterial antagonist test against the fungus Fusarium sp. with the dual culture method showed that 6 out of 14 isolates were able to inhibit the growth of the fungus Fusarium sp. Isolates TTSG 2.2, TTSG 2.7, TTSG 3.2, TTSG 3.5, TTSG 3.6, and TCS 3.1 had inhibitory power of 45%. One of the six isolates of rhizosphere bacteria, namely TTSG 3.6, showed a negative reaction in the hemolysis test. These results indicate that the bacterial isolate of TTSG 3.6 has the potential to be used as a control for Fusarium sp. on tomato plants, Salah satu masalah dalam pertanian tomat (Solanum lycopersicum L.) ialah munculnya penyakit layu, yang disebabkan oleh cendawan patogen Fusarium sp. Cendawan patogen selama ini dikendalikan dengan menyemprotkan fungisida sintetik. Pengunaan fungisida berdampak negatif terhadap organisme lain dan lingkungan. Dampak negatif dari penggunaan bahan kimia sintetis berlebihan, dapat dikurangi pengunaannya dengan agens biokontrol yang menghasilkan senyawa anticendawan. Usaha pengendalian cendawan patogen secara alami menggunakan bakteri rizosfer sebagai pengendali pertumbuhan cendawan patogen pada tanaman tomat (Solanum lycopersicum L) masih belum banyak dilaporkan. Penelitian ini bertujuan untuk menyeleksi bakteri rizosfer dari 14 isolat bakteri yang telah diisolasi dari pertanian tanaman tomat yang mampu menghambat pertumbuhan Fussarium sp. secara invitro dan melakukan karakterisasi bakteri terpilih. Hasil uji antagonis bakteri terhadap cendawan Fusarium oxysporum dengan metode dual culture menunjukkan bahwa sebanyak 6 dari 14 isolat mampu menghambat pertumbuhan cendawan Fusarium sp. Isolat TTSG 2.2, TTSG 2.7, TTSG 3.2, TTSG 3.5, TTSG 3.6, dan TCS 3.1 memilki daya hambat 45%. Satu dari enam isolat bakteri rizosfer yaitu TTSG 3.6 menunjukkan reaksi negatif dalam uji hemolisis. Hasil ini menunjukkan bahwa isolat bakteri TTSG 3.6 berpotensi digunakan sebagai pengendali Fusarium sp. pada tanaman tomat
Keyword: biocontrol, hemolysis test, percentage of inhibition, rhizosphere

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