Judul: Antioxidant Activity of Spirulina platensis During Fermentation Using Lactic Acid Bacteria From Bekasam
Abstrak: Spirulina platensis merupakan mikroalga hijau kebiruan jenis cyanobacteria yang memiliki aktivitas antioksidan. Lactobacillus plantarum SK(5) dan Pediococcus pentosaceus BP(20) bersifat sebagai probiotik dan dapat digunakan secara langsung dalam makanan fermentasi. Penelitian ini bertujuan menentukan karakteristik kimiawi, mikrobiologis, dan aktivitas antioksidan S. platensis selama fermentasi menggunakan bakteri asam laktat (BAL) L. plantarum SK(5) atau P. pentosaceus BP(20). Penelitian ini terdiri atas 3 tahap yaitu kultivasi dan pemanenan biomassa S. platensis, penyiapan kultur starter SK(5) dan BP(20), dan fermentasi spirulina menggunakan starter BAL asal bekasam selama 72 jam inkubasi. Spirulina hasil kultivasi dapat dipanen pada hari ke-14. Spirulina fermentasi mengalami penurunan pH selama 48 jam dan peningkatan pada jam ke-72, serta peningkatan total asam tertitrasi (TAT) dan total BAL selama 48 jam kemudian penurunan pada jam ke-72. Peningkatan total fenol dan aktivitas antioksidan pada spirulina fermentasi dengan kultur BP(20) mencapai 25,43% dan 56,77% selama 48 jam, sedangkan peningkatan total fenol dan aktivitas antioksidan dengan kultur SK(5) mencapai 117,73% dan 188,18% selama 72 jam., Spirulina platensis is cyanobacteria (blue-green algae) that has antioxidant activity. Lactobacillus plantarum SK(5) and Pediococcus pentosaceus BP(20) that as probiotics and can be used directly in fermented foods. This study aimed to determine the chemical, microbiological, and antioxidant activity of S. platensis during fermentation using LAB L. plantarum SK(5) and P. pentosaceus BP(20). The procedure of this study consist of 3 stages, namely culturing of S. platensis, the preparation culture starter of SK(5) and BP(20), and fermentation of spirulina using LAB from bekasam for 72 hours. The spirulina culture was harvested on the 14th day. Fermented spirulina decreased in pH for 48 hours and increased at 72 hours, and increased TAT and LAB for 48 hours then decreased at 72 hours. The increase in total phenol and antioxidant in fermented spirulina with BP(20) reached 25,43% and 56,77% for 48 hours, while the increase in total phenol and antioxidant with SK(5) reached 117,73% and 188,18% for 72 hours.
Keyword: antioxidant, fermented spirulina, lactic acid fermentation, Lactobacillus plantarum SK(5), Pediococcus pentosaceus BP(20)

Judul: Chemical Characterization of Fermented Spirulina and Screening of Metabolic Compounds Produced by it
Abstrak: Spirulina platensis dapat menstimulasi pertumbuhan mikroba non patogenik. Penelitian sebelumnya menunjukkan Spirulina fermentasi memiliki karakteristik kimiawi dan aktivitas antioksidan. Pengeringan beku (liofilisasi) dilakukan dan digunakan dalam penelitian ini. Penelitian bertujuan menentukan karakteristik kimiawi dan penapisan senyawa metabolit dari Spirulina fermentasi setelah liofilisasi. Spirulina fermentasi liofilisasi memiliki nilai pH 4,15 ± 0,00, total asam tertitrasi (TAT) 11,96 ± 0,00 %, dan total bakteri asam laktat (BAL) <2,5 × 101 ± 0,00. Spirulina fermentasi mengandung komponen aktif flavonoid, steroid, tanin, saponin dan fenol hidrokuinon, serta negatif alkaloid. Penapisan senyawa metabolit menggunakan LC-MS/MS menghasilkan 88 senyawa, terdiri dari golongan terpen atau terpenoid, fenolik, dan alkaloid, serta kelompok asam amino, asam lemak, asam organik, natural pigmen, gula dan kelompok lainnya. Senyawa dominan teridentifikasi diantaranya propenyl pyrazine, ribonic acid, pyroglutamic acid, phenyllactic acid, 1,2-cyclohexanedicarboxylic acid, didecyl ester, cis-caftaric acid, malic acid, 1,2-cyclohexanedicarboxylic acid, cyclohexylmethylnonyl ester, dan gallic acid., Spirulina platensis can stimulate the growth of non-pathogenic microbes. Previous studies have shown that lyophilized fermented Spirulina and Spirulina biomass have antioxidant activity. The study aims to determine the chemical characteristics and screening of metabolites produced by lyophilized fermented Spirulina and Spirulina biomass. Lyophilized fermented Spirulina had a pH value of 4,15 ± 0,00, total titrated acid (TAT) 11,96 ± 0,00%, and total lactic acid bacteria (LAB) < 2,5 × 101 ± 0,00. Fermented Spirulina contains active components of flavonoids, steroids, tannins, saponins and phenol hydroquinone, as well as negative alkaloids. Screening of metabolites using LC-MS/MS resulted in 88 compounds, consisting of terpenes or terpenoids, phenolics, and alkaloids, as well as groups of amino acids, fatty acids, organic acids, natural pigments, sugars and other groups. The dominant compounds identified were propenyl pyrazine, ribonic acid, pyroglutamic acid, phenyllactic acid, 1,2- cyclohexanedicarboxylic acid, didecyl ester, cis-caftaric acid, malic acid, 1,2- cyclohexanedicarboxylic acid, cyclohexylmethylnonyl ester, and gallic acid.
Keyword: Lactobacillus plantarum SK (5), Spirulina, metabolomic, metabolites

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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