Judul: Eksplorasi Spasial Karang Lunak Kaitannya dengan Senyawa Bioaktif Bakteri Simbion.
Abstrak: In ecology, soft and hard corals have the same function in the waters. The distribution of soft corals is strongly influenced by the characteristics of the aquatic environment. Soft corals had been knows contain of bioactive compounds that can be used as a marine natural product, but naturally theses resource are limited and very difficult to cultivated. Therefore, the isolation of bacterial symbiont on soft coral is one of alternatives in an effort to utilize these resources in sustainability. This study had four main objectives that include the following: (1) to determine the differences of the soft corals between sheltered and exposed area in Pongok Island, Soulth of Bangka and Tegal Island in Lampung Bay, Indonesia; (2) to find of the soft corals inhibition potential for antibacterial activity; (3) to measure the antibacterial activity level and minimum inhibitory concentration of bioactive compounds in the soft coral S. flexibilis and S. polydactyla species; (4) to find the isolation of bacterial symbionts from soft coral S. flexibilis and S. polydactyla species that the potential to producted bioactive compound. The results found eigtht types of soft corals classified in four genera (Lobophytum, Nephthea, Sarcophyton and Sinularia) were found in both sites, six species were identified in the waters of South Bangka (at 9 meters depth) and two species (at 3 meters depth). In Tegal Island waters (closed waters), only 2 species from the genus Sinularia were recorded (at 2-5m depth). There were 2 stations at Pongok Island namely, PGK1 and PGK2, while in Tegal Island, there were 4 stations namely TGL1, TGL2, TGL3 dan TGL4. Principal component analyses showed that both waters can be classified based on their physical-chemical characteristic, which were depth, currents, phosphate and turbidity waters. Discriminant function were showed in phosphate variable. While the similarity analysis showed that both waters had very strong similarity of about 79%. In sampling treatment, the biomass among wet and dry samples varied. The highest shrinkage due to drying was found in Nephthea, followed by Lobophytum and Sarcophyton, while the lowest was found in the genus of Sinularia. Extracted from 12 samples of soft coral, the lowest extract weight was found in the semipolar solvent (EtOAc), while the extract weight of n-Hex and MeOH was vary. Inhibition power from all extract samples were found on soft coral extract in the EtOAc and MeOH solvents. The highest value of inhibition power was found in soft coral of Sinularia polydactyla and S. flexibilis within strong catogery. Principal component analysis showed there were corelations between the the environment characteristics with the bioactive compounds inhibition of soft corals, that the identifier parameters include; depth, currents, phosphate and turbidity waters. Discriminant function were showed in depth variable. Extracts weight of both species S. flexibilis (SFTLS4) and S. polydactyla (SPTLS2) found the same relatively, except extract in n-Hexane (n-Hex) solvent from SFTLS4 samples that higher compered to extract weigth in other solvents. vii Antibacterial activites of both spesies showed only on extract in ethyl acetate (EtOAc), within strong category. For purification were obtained eigth fractions (F1-F8) for SFTLS4 extractions and six fractions (F1-F6)
Keyword: antibacterial activity, bacterial symbiont, bioactive compound, sinularia, soft coral

Judul: Toksisitas Ekstrak Senyawa Bioaktif dari Bakteri yang Berasosiasi dengan Spons dan Analisis DNA yang Berperan dalam Biosintesisnya
Abstrak: Sponges are organisms that produced many bioactive compounds and live symbiotically with many microorganisms. Symbiont microorganisms act as producers of bioactive compounds for sponge self-defense. This study aims to test the toxicity of the ethyl acetate extract sponge-associated bacteria against Artemia salina larvae and diversity analysis of DNA that play a role in the synthesis of bioactive compounds. BSLT was used as toxicity assay method and obtained LC50 values ranged from 117.1 μg/mL to 620 μg/mL. Fractionation of the ethyl acetate extract for isolates SAB E-35, SAB E-38 and SAB E-40 using preparative thin layer chromatography technique (PTLC) yielded fraction with the best LC50 value 116.7 μg/mL. Fraction 38-E of isolate SAB E-38 showed increase in LC50 value from its etyl acetat extract 138.6 μg/mL to 116.7 μg/mL. Isolates SAB E-35, SAB E-38, and SAB E-40 has gene that encoded the KS domain of PKS and A domain of NRPS with homology percentage from 47% to 100%. SAB E-40 has low homology and expected as potential producer of new bioactive compounds
Keyword: toxicity, sponge-associated bacteria, PKS, NRPS

Judul: Analysis of M/G/1 Queue Model with Two Phases of Service and Bernoulli Feedback System
Abstrak: Model antrean M/G/1 dengan sistem feedback Bernoulli adalah model antrean dengan proses kedatangan mengikuti proses Poisson. Pada karya ilmiah ini dibahas sistem antrean M/G/1 dengan dua fase layanan. Setelah layanan pertama selesai, pelanggan dapat memilih untuk meninggalkan sistem dengan peluang ... dst, The M/G/1 queueing model with the Bernoulli feedback system is a queueing model with the arrival process following the Poisson process. In this manuscript M/G/1 queueing system with two phases of service is discussed. After the first service is completed, the customer can choose to leave the system with probability ... dst
Keyword: queue, Bernoulli, probability generating function, expected value