Judul: Produksi Biodisel Secara Transesterifikasi In Situ dari Mikroalga Chlamydomonas sp. dan Synechococcus sp. yang Dikultivasi dengan Media Teknis
Abstrak: During the time being, the world’s oil supply is going to be less. In the other side, enviroment pollution derived from fosil fuel combustion is going tobe more extensive. Indonesia has 9 billion barrel of oil reserve which will be run out in 23 years. Therefore, alternative source of energy should be developed, such as biodiesel. Microalgae have a high productivity and potential to be developed as biodiesel. This development need a high cost. This study is intended to find an alternativeof biodiesel production from microalgae which is more cost efficient. We developed a new improvement by using technical grade culture nutrient and in situtransesterification process. The study consisted of three stages. The first was regeneration and providing four isolates in BG 11 medium. The second was cultivation in lab scale, aquarium scale using N2P1, N2P2 or N3P3 medium, and analyses of lipid, water, ash, yield, free fatty acid (FFA), and characterization of the fatty acid. The last was biodiesel production byin situtransesterification process,yield measurement and characterization of the biodiesel. Isolate Chlamydomonas sp. ICBB 9114 produced the highest yield of biomass (0.44 g/L) with low water content, whileChlamydomonas sp. ICBB 9112 produced the lowest biomass (0.19 g/L) with the highest water and FFA content. Synechococcus sp. ICBB 9111 had the highest ash content, whileChlamydomonas sp. ICBB 9113 had the lowest ash and FFA content. Fatty acid content with C18:3 type was dominant in Synechococcus sp. ICBB 9111 (47.03%), Chlamydomonas sp. ICBB 9113 (42.57%), and Chlamydomonas sp. ICBB 9114 (34.42%). While, C16:0 type was dominant in Chlamydomonas sp. ICBB 9112. It marked that Chlamydomonas sp. ICBB 9112 had a good quality of FA which could be used as biodiesel needing a low melting point, high cetan number, and unoxidizable. After lipid extraction, the process was continued with convertion to fatty acid metyl ester (FAMEs) through transesterification process. Chlamydomonas sp. ICBB 9114 produced the highest FAMEs (3523.20 mg/100 g). The characteristics of the biodiesel originated fromChlamydomonas sp. ICBB 9114 producedby in situ transesterficationwere suitable with SNI biodiesel criteria except for the acid value.
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Judul: Optimization Process Of Ethanol Production From Microalgae Chlamydomonas Sp. Icbb 9113, Icbb 9114 And Synechococcus Sp. Icbb 9111
Abstrak: The production of crude oil in Indonesia is 860 thousand barrel per day. Total crude oil reserves in Indonesia today is 7,4 billion barrels, and it is estimated to be exhausted in 24 years. National energy policy targets the utilization of non-fossil energy by 5-20% in the year 2005-2020. The first generation of alternative energy materials used are crude palm oil, jatropha, cassava and corn. The potential feedstock other than terrestrial plants are aquatic organisms e.g microalgae. Components of microalgae such as lipids for biodiesel and carbohydrates to ethanol. Ethanol production from biomass of microalgae consist of two stages i.e. saccharification and fermentation. Problem often found in the saccarification process is low reducing sugar when using acid hydrolysis. Therefore, it is necessary to find an alternative approach to increase the sugar yield by using enzymes. The study consists of four stages. The first was regeneration three isolates in BG 11 medium. The second was cultivation in laboratory using N2P1, N2P2 and N3P3 medium. The commercial enzyme of α-amylase and amyloglucosidase was analyzed to determine the optimal temperature and pH of its activity. The last was evaluating ethanol production using α-amylase and amyloglucosidase. The results of hydrolysis then fermented for seven days using Saccharomyces cereviceae ICBB 8808 to produce ethanol. Microalgae Chlamydomonas sp. ICBB 9114 has the highest biomass yield of 0,44 g/L with a 14,16% starch content, whereas the biomass yield and the lowest starch content in Synechococcus sp. ICBB 9111. The results characterization of α-amylase, optimum at pH 7 and temperature of 90°C with enzyme activity of 63,69 U/mL, whereas the best characterization of amyloglucosidase obtained at pH 5,5 and temperature of 60°C with the enzyme activity of 148,59 U/mL. The hydrolysis of three types microalgae using α-amylase obtained the highest reducing sugars in the microalgae Chlamydomonas sp. ICBB 9114 (5,62 mg/mL). The lowest of reducing sugars obtained on microalgae Chlamydomonas sp. ICBB 9113 (4,39 mg/mL). The combination of the two types of enzymes α-amylase and amyloglucosidase the hydrolysis process increases the total reducing sugars (P<0,05) in all three types of microalgae. The highest reducing sugars produced in the microalgae Chlamydomonas sp. ICBB 9114 (41,83 mg / mL), whereas the lowest reducing sugar produced microalgae Synechococcus sp. ICBB 9111 (35,67 mg/mL). After fermentation for 96 hours on three types of microalgae to produce ethanol. Synechococcus sp. ICBB 9111 (920 ppm), Chlamydomonas sp. ICBB 9113 (980 ppm) and Chlamydomonas sp. ICBB 9114 (516 ppm) respectively.
Keyword: Enzyme, ethanol, fermentation, microalgae, saccharification

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf