Judul: Characterization of indigenous lactic acid bacteria from beef as probiotic and identification by 16s rRNA gene sequencing
Abstrak: Functional foods are foods that have health promising benefit over and above their basic nutritional value. Probiotics are included as component of functional foods. Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. The research was aimed to characterize the probiotic properties and to identify indigenous lactic acid bacteria (LAB) isolated from fresh beef derived from traditional market around Bogor, West Java, Indonesia. The twenty eight LAB isolates showed different ability to survive under simulated gastrointestinal conditions. Only 10 isolates could survive well at pH 2.0 (survival rate over than 50%) and the population increased at pH 2.5, 3.2 and 7.2. The ten LAB isolates (strain 2B4, 1B1, 1A5, 2C2, 2D1, 2B2, 1C4, 2B1, 1A32 and 2C12) could survive well at 0.5% bile salt, showed antibacterial activities and good coagregation capabilities against the tested pathogenic bacteria (Escherichia coli ATCC 25922, Salmonella Typhimurium ATCC 14028, Enteropathogenic Escherichia coli/EPEC, and Staphylococcus aureus ATCC 25923) and could adhere to intestinal surface by in vitro analysis. The 16S rRNA gene could be amplified by PCR (Polymerase Chain Reaction) to get single band with designed primer. Identification by 16S rRNA gene sequencing of 20 isolates showed that 11 isolates were identified as Lactobacillus plantarum, 6 isolates as Lactobacillus acidophilus, 2 isolates as Pediococcus pentosaceous and 1 isolate as Enterococcus faecium. The ten LAB isolates were proven to be probiotic candidates, which consist of 7 isolates of Lactobacillus plantarum (strain 1B1, 1A5, 2D1, 2B2, 1C4, 2B1, 2C12) and 3 isolates of Lactobacillus acidophilus (strain 2B4, 2C2, 1A32). Lactobacillus plantarum 2C12 and Lactobacillus acidophilus 2B4 were further evaluated to prevent diarrheae caused by EPEC. Albino rats (Rattus norvegicus) were daily orally administered by 108 cfu/ml of both probiotics without or simultaneously infected with EPEC (106 cfu/ml). Negative control was not infected by probiotic and EPEC while positive control was challenged with EPEC alone. It was observed that rats administered by L. plantarum 2C12 and L. acidophilus 2B4 which were challenged with EPEC had better performances when compared with the positive control for daily weight gain, feed consumption and feed efficiency rate. Both probiotics could prevent diarrhea caused by EPEC by increasing total population of lactic acid bacteria 1 log cfu/cm2 on mucosa of cecum and 1 log cfu/g on content of cecum, reducing population of E.coli 1-2 log cfu/cm2 on mucosa of cecum and 1 log cfu/g on cecum content also increasing 33.66-71.79 x 106 cell on lymphocytes. L. acidophilus 2B4 had better probiotic characteristics than L. plantarum 2C12, with specific health function to prevent diarrhea caused by EPEC.
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Judul: Karakteristik Pertumbuhan Bakteri Asam Laktat Indigenous Susu Sapi Segar Sebagai Kandidat Bakteri Probiotik Dalam Saluran Pencernaan in vitro
Abstrak: Functional foods in the form of probiotic yogurt serves as a food that provides health effects, especially in the digestive tract. This probiotic yogurt can maintain the balance the intestinal microflora, especially between beneficial and pathogen bacterials. Terms of the probiotic bacteria concerned to lactic acid bacteria that were able to survive at the digestive tract. The purpose of this study was to investigate the characteristics of lactic acid bacteria indigenous cow’s milk as a candidate of probiotic bacteria. Resistancy of lactic acid bacteria through different pH conditions, in presence of bile salts or antibiotics, were tested in the media that was conditioned as human digestive tract (in vitro). Lactic acid bacteria resistance was seen through a comparison of the original population before the treatment and the population after treatment. The results of this study, bacteria L. acidophilus Y-01, B. longum Y-01 and L. bulgaricus S-01 can be used as candidates probiotic bacteria because it survived in a pH condition (pH 2, 2,5, 3,2 and 7,2), the condition of bile salts, and antibiotics. Although the population of S. thermophilus S-01 and L bulgaricus S-01 decreased after treatment, all four of these bacteria also produce antimicrobial evidenced by the clear zone that formed around the supernatant. This antimicrobial activity showed inhibition to the growth pathogenic bacteria (E. coli, S. Typhimurium, and S. aureus).
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular