Judul: Biosurfactant Activity of Bacillus sp. strain LP04 Isolate and Its Antifungal Potency against Ganoderma boninense
Abstrak: Biosurfaktan adalah salah satu kelas dari molekul amfipatik yang dapat diproduksi oleh berbagai mikroorganisme. Biosurfaktan dimanfaatkan sebagai biopestisida dan agens biokontrol, karena memiliki aktivitas antimikrob khususnya sebagai agens anticendawan pada beberapa spesies cendawan patogen seperti Ganoderma boninense yang menyerang tanaman kelapa sawit. Penelitian ini bertujuan mendeteksi aktivitas biosurfaktan dari isolat Bacillus sp. galur LP04 dan potensinya sebagai agens anticendawan terhadap cendawan Ganoderma boninense. Biosurfaktan diproduksi pada media mineral salt medium (MSM) dengan cara memanen supernatan bebas sel. Penapisan isolat penghasil biosurfaktan dilakukan dengan uji oil spreading assay, hemolysis assay, dan indeks emulsifikasi. Aktivitas anticendawan isolat kemudian diuji dengan metode agar diffusion. Isolat Bacillus sp. galur LP04 merupakan bakteri Gram positif yang berpotensi memiliki aktivitas biosurfaktan yang dicirikan dengan hasil positif pada uji oil spreading assay, dan memiliki indeks emulsifikasi 48.33 ± 2.87%. Isolat bakteri ini dapat menghambat pertumbuhan cendawan Ganoderma boninense dengan persentase penghambatan sebesar 51.11%., Biosurfactants are a class of amphipathic molecules that can be produced by various microorganisms. Biosurfactants are used as biopesticides and biocontrol agents, because they have antimicrobial activity, especially as antifungal agents in several species of fungal pathogens such as Ganoderma boninense that attack the palm oil trees. This study aims to detect the biosurfactant activity of Bacillus sp. strain LP04 and its potential as antifungal agent against the fungi Ganoderma boninense. Biosurfactants were produced in mineral salt medium (MSM) by harvesting cell-free supernatants. Screening of biosurfactant-producing isolates was carried out by oil spreading assay, hemolysis assay, and emulsification index. The antifungal activity of the isolates was then tested by the agar diffusion method. Bacillus sp. strain LP04 is a Gram-positive bacterium that has the potential to have biosurfactant activity which is characterized by a positive result on the oil spreading assay test, and has an emulsification index of 48.33 ± 2.87%. This bacterial isolate was able to inhibit the growth of Ganoderma boninense with the growth inhibition rate of 51.11%.
Keyword: Emulsification index, inhibition percentages, lipopeptide, oil spreading

Judul: Detection of Ethyl Stearate Compound Produced by Bacillus subtilis MN704394.1 Using GC-MS as Antifungal for Ganoderma boninense
Abstrak: G. boninense merupakan jamur penyebab penyakit busuk pangkal batang pada kelapa sawit yang salah satunya pengendaliannya dapat menggunakan agen biokontrol berupa bakteri B. subtilis karena ramah lingkungan dan kemampuan beradaptasi yang kuat. Penelitian ini bertujuan mendeteksi etil stearat yang dihasilkan oleh B. subtilis MN704394.1 sebagai senyawa bioaktif untuk menghambat pertumbuhan G. boninense pada tanaman kelapa sawit. Supernatan kultur B. subtilis diekstraksi pada 5 titik pengambilan, yaitu jam ke-8, ke-12, ke-16, ke-20, dan ke-24 dengan etanol. Ekstrak kasar diuji aktivitas penghambatannya terhadap G. boninense dengan metode simultan, preventif, dan kuratif. Senyawa bioaktif pada ekstrak yang berpotensi sebagai antijamur diidentifikasi menggunakan GC-MS. Hasil penelitian menunjukkan aktivitas penghambatan oleh ekstrak jam ke-8 dengan metode preventif paling tinggi persen penghambatannya, yaitu 96,44%. Salah satu senyawa bioaktif hasil analisis GC-MS yang terdapat pada semua titik jam dan memiliki konsentrasi yang tinggi, yaitu etil stearat. Etil stearat hasil GC-MS pada jam ke-8 memliki area sebesar 10,3018% dan waktu retensi pada 22,1221. Etil stearat termasuk asam lemak ester dan memiliki aktivitas penghambatan tehadap G. boninense., G. boninense is a pathogen that causes basal stem rot disease in oil palm which can be controlled by using biocontrol agents such as B. subtilis because it’s environmentally friendly and strong adaptability. This study aims to detect ethyl stearate produced by B. subtilis MN704394.1 as bioactive compound to inhibit the growth of G. boninense in oil palm. The supernatant of B. subtilis culture was extracted in 5 points cultivation 4th, 8th, 12th, 16th, 20th, and 24th hour using ethanol. The crude extracts activity was tested with simultant, preventive, and curative method. Analysis of bioactive compounds was conducted using GC-MS. Activity test of bacterial extract showed that the extract at 8th hour with preventive method had the highest inhibitor activity that is 96.44%. One of bioactive compounds from the GC-MS analysis that exists in all points of cultivation and has high concentration is ethyl stearate. Ethyl stearate at 8th hour has area 10,3018% and retention time 22,1221. Ethyl stearate is fatty acid ester and played role in inhibitory activity of G. boninense.
Keyword: antifungal, Bacillus subtilis, ethyl stearate, Ganoderma boninense

Judul: Implementasi Space Time Composite (STC) Data Model Menggunakan Model Data Relasional
Abstrak: The data model is a concept that describes the data stored in the database and the relationship between the data to the user in logic. Development of data models is very important in the design of the database as the basis of the stage of database design to be made. This study aims to apply the concept of Space Time Composite (STC) on the Model Data storage vector data types that can store enough information and describes the process of drafting objects and objects spatiotemporal evolution over time. From the results of the test queries on the data model that have been created, queries in a system are acquired that can help display the information preparation of objects from time to time and know the history of the object polygon and arc that has undergone changes in topology.
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