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 Ketahanan Bakteri Asam Laktat Indigenous Dadiah Sebagai Kandidat Probiotik Pada Kondisi Saluran Pencernaan in vitro
Abstrak: Probiotic bacteria defined as living microorganisms which will confer health benefit to the host when administered in adequate amounts. The aims of this research were to study the potential of Lactobacillus plantarum D-01, Lactococcus lactis D-01, Bifidobacterium longum Y-01, and Lactobacillus acidophilius Y-01 as probiotic bacteria through its ability to survive in gastrointestinal conditions (acid conditions of stomach and the presence of bile salts in the small intestine), its resistance to antibiotics, and its antimicrobial properties against pathogen bacterias. This study initiated with assays of four tested Lactic Acid Bacterias for its ability to grow and survive in acid conditions and the presence of bile salts or antibiotics, also its antagonistic activities against indicator strains of pathogen bacterias (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Salmonella Thypimurium ATCC 14028). Result showed the ability of L. plantarum D-01, L. lactis D-01, B. longum Y-01 and L. acidophilus Y-01 to grow in acid conditions and tolerance at the presence of bile salts and antibiotics (t-test). Research found that difference species LABs tested influenced diameter of the inhibition zone against pathogen indicator bacterias (P<0.01). L. acidophilus Y-01 had the largest inhibition zone against S. Thypimurium ATCC 14028 and E. coli ATCC 25922, while B. longum Y-01 was able to produce the largest inhibition zone against S. aureus ATCC 25923 (P<0,05). Based on the characterization of four species LAB, it could be concluded that L. plantarum D-01, L. lactis D-01, B. longum Y-01, and L. acidophilius Y-01 can be used as probiotic.
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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