Judul: Antibacterial activity of Bombyx mori and Samia cynthia ricini sericin proteins against Escherichia coli and Staphylococcus aureus
Abstrak: This study was designed to investigate the antibacterial properties of the sericin protein Bombyx mori and Samia cynthia ricini against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus strains. Sericin protein was extracted from the cocoons of B. mori races A, B, C, D, F1-1, F1,2 and S. ricini from Indonesia using a degumming process. Afterwards, the extract sericin protein were evaluated as antimicrobial such as Kirby Breuer disc diffusion, spectrometer measurement in decreasing OD value, and imaging Scanning Electron Microscope (SEM). The tests revealed that sericin protein from B. mori was more capable of inhibiting bacteria S. aureus than E. coli, whereas sericin protein from S. ricini was capable of strongly inhibiting both S. aureus and E. coli bacteria. The sericin proteins of B. mori and S. ricini were found to reduce the number of S. aureus and E. coli bacteria as the OD value decreased at a concentration of 9%. According to SEM imaging, sericin B. mori and S. ricini proteins caused changes in cell morphology in S. aureus and E. coli bacteria, resulting in bacterial cell function disruption and death. Sericin protein B. mori and S. ricini were able to against bacteria S. aureus than E. coli. Therefore, sericin protein is a potential to be antibacterial, particularly against Gram-positive strain S. aureus.
Keyword: antibakteri, Bombyx mori, Samia cynthia ricini, serisin

Judul: Purification and Characterization Sericin Protein Cocoon of Eri (Samia cynthia ricini) silkworm
Abstrak: Protein serisin merupakan perekat antar serat (fibril). Protein serisin diekstraksi dari limbah air degumming serat sutra. Serisin Samia cynthia ricini didapatkan dengan melakukan degumming menggunakan NaOH 0,033N dengan kombinasi suhu dan waktu 113 oC selama 34 menit. Hasil crude protein serisin kemudian dipurifikasi dengan netralisasi menggunakan HCL serta presipitasi etanol. Hasil purifikasi dikarakterisasi berat molekulnya menggunakan sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) dan didapatkan hasil berat molekul serisin sebesar 7,08 kDa. Asam amino serisin S. ricini dikarakterisasi menggunakan high performance liquid chromatography (HPLC) dan dihasilkan asam amino tertinggi pada glisina (15,35%). Aktivitas dalam penghambatan DPPH diketahui sebesar 66,86% dengan kapasitas antioksidan 8,03 mg VCE mL-1. Sifat antibakteri dimiliki serisin S. ricini terhadap bakteri S. aureus dengan zona hambat 6,74 mm dan persentase penurunan kekeruhan 80.04%., Sericin is a protein that acts as an adhesive joining two fibroin filaments. Sericin protein was extracted from silk wastewater. Silk wastewater was produced from degumming of cocoon Samia cynthia ricini with NaOH 0,033N and a combination of temperature and time 113 oC for 34 minutes. Crude sericin protein was purified with neutralization of HCL and ethanol precipitation. The molecular weight of purified protein was investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and the results of S. ricinisericin molecular weight is 7,08 kDa. The amino acid of S. ricini sericin was investigated by high performance liquid chromatography (HPLC) that result in highest component is glycine (15,35%). Sericin S. ricini has 66,86% antioxidant activity with 8,03 mg VCE mL-1 antioxidant capacity. Antibacterial attribute of sericin S. ricini inhibit toward S. aureus bacteria with 6,74 mm inhibition zone and 80,04% in turbidity decrease percentage.
Keyword: purification, Samia cynthia ricini, sericin, SDS-PAGE, HPLC

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