Judul: Growth and Content of Lipid Metabolites Microalgae Cultures of Chlorella vulgaris and Nannochloropsis sp. in Nitrogen Deficiency Conditions
Abstrak: Chlorella vulgaris dan Nannochloropsis sp. merupakan mikroalga yang memiliki kandungan lipid tinggi dengan produktivitas lipid yang lebih tinggi daripada tumbuhan penghasil minyak, sehingga berpotensi sebagai sumber energi baru dan terbarukan. Analisis kandungan lipid dari kedua spesies tersebut sudah dipelajari, tetapi perbandingan respons pertumbuhan serta kandungan asam lemak dalam kondisi defisiensi nitrogen perlu dipelajari lebih lanjut. Penelitian ini bertujuan menganalisis respons pertumbuhan dan kandungan metabolit lipid dari C. vulgaris dan Nannochloropsis sp. dalam kondisi defisiensi nitrogen. Metode yang dilakukan adalah kultur mikroalga, ekstraksi lipid, analisis metabolomik, dan analisis data. Respons pertumbuhan C. vulgaris dan Nannochloropsis sp. dalam media defisiensi nitrogen adalah menurunnya densitas sel masing-masing sebesar 19,2% dan 40,4%, menurunkan bobot biomassa basah sebesar 41,5% dan 62,2%, tetapi dapat meningkatkan bobot ekstrak lipid per biomassa basah berturut-turut sebesar 36,4% dan 38,9%. Kandungan metabolit lipid kultur C. vulgaris dan Nannochloropsis sp. pada kondisi defisiensi nitrogen meningkatkan kandungan asam lemak masing-masing sebesar 70,2% dan 47,1% dan dengan dominasi berupa asam lemak jenuh, yaitu asam heksadekanoat (C16:0) dan asam oktadekanoat (C18:0). Analisis PCA dan dendrogram dari kedua spesies mikroalga menghasilkan bahwa metabolit lipid pada kondisi normal berbeda dengan metabolit lipid pada kondisi defisiensi nitrogen., Chlorella vulgaris and Nannochloropsis sp. are microalgae that have high lipid content which is higher than oil-producing plants, so they have the potential as a new and renewable energy source. Analysis of the lipid content of both species has been studied, but a comparison of growth response and fatty acid content under nitrogen deficiency conditions needs further study. This study aims to analyze the growth response and lipid metabolite content of C. vulgaris and Nannochloropsis sp. under nitrogen deficiency conditions. The methods used were microalgae culture, lipid extraction, metabolomics analysis, and data analysis. The growth responses of C. vulgaris and Nannochloropsis sp. in nitrogen-deficient media were decrease in cell density of 19,2% and 40,4% respectively, decrease in wet biomass weight by 41,5% and 62,2% but could increase the lipid extract per wet biomass by 36,4% and 38,9%. The lipid metabolite content of C. vulgaris and Nannochloropsis sp. under nitrogen deficiency conditions increased the fatty acid content by 70,2% and 47,1% with the predominance of saturated fatty acids, namely hexadecanoic acid (C16:0) and octadecanoic acid (C18:0). PCA and dendrogram analysis of both microalgae species showed that lipid metabolites under normal conditions were different from lipid metabolites under nitrogen-deficient conditions.
Keyword: biofuel, biomass, metabolomics, lipid accumulation

Judul: Expression of bZIP1 and LEC1 Genes and Lipid Content in  Microalgae Nannochloropsis sp. Cultures Under Salinity Stress
Abstrak: Mikroalga Nannochloropsis sp. merupakan kandidat penghasil bahan bakar berupa biofuel. Hal ini disebabkan, kemampuannya mengakumulasi lipid dalam jumlah tinggi, terutama pada kondisi cekaman. Pembentukan lipid dipengaruhi oleh faktor transkripsi berupa gen Basic Leucine Zipper 1 (bZIP1) dan Leafy Cotyledon 1 (LEC1). Penelitian ini bertujuan menganalisis ekspresi gen bZIP1 dan LEC1 dalam kultur mikroalga Nannochloropsis sp. pada kondisi cekaman salinitas dan hubungannya dengan biosintesis lipid. Isolat Nannochloropsis sp. dikultur pada kultur peralihan, kemudian pada kultur kontrol dan perlakuan cekaman salinitas tinggi dan rendah. Analisis ekspresi gen dilakukan dengan isolasi RNA, sintesis cDNA, dan analisis qRT-PCR. Pengukuran lainnya adalah densitas sel, bobot biomassa, dan kandungan lipid. Hasil qRT-PCR menunjukkan peningkatan secara signifikan ekspresi gen relatif bZIP1 sebesar 340 kali dan LEC1 sebesar 18.000 kali pada kultur Nannochloropsis sp. yang mengalami cekaman salinitas tinggi, dan sebaliknya hampir tidak terdeteksi pada kultur yang mengalami cekaman salinitas rendah dibandingkan kontrol. Densitas sel kultur mikroalga menurun pada perlakuan cekaman salinitas tinggi dan rendah berturut-turut sebesar 38,3% dan 16,3% saat fase stasioner, serta penurunan bobot biomassa berturut-turut sebesar 45,9% dan 40,8%. Kandungan lipid pada kultur mikroalga cekaman salinitas tinggi mengalami peningkatan sebesar 35,3% dan kandungan lipid pada kultur mikroalga cekaman salinitas rendah mengalami penurunan sebesar 34,4%., Nannochloropsis sp. is a promising candidate for producing biofuel, a substitute for fossil fuels. This is due to its ability to accumulate high levels of lipids, especially under stress conditions. Lipid formation is influenced by transcription factors such as Basic Leucine Zipper 1 (bZIP1) and Leafy Cotyledon 1 (LEC1). This study aims to analyze the expression of bZIP1 and LEC1 genes in Nannochloropsis sp. cultures under salinity stress conditions and their relationship with lipid biosynthesis. Nannochloropsis sp. isolates were initially cultured in transition culture, then subcultured in control and salinity stress conditions. Gene expression analysis involved RNA isolation, cDNA synthesis, and qRT-PCR. Cell density, biomass weight, and lipid content were assessed. qRT-PCR showed a significant increase in the relative gene expression of bZIP1 by 340 times and LEC1 by 18.000 times in Nannochloropsis sp. cultures under high salinity stress, while expression was almost undetectable under low salinity stress compared to the control. Cell density of Nannochloropsis sp. cultures decreased by 38,3% and 16,3% respectively, during the stationary phase, with biomass weight reductions of 45,9% and 40,8%, respectively. Lipid content in high salinity stress culture increased by 35.3%, while lipid content in low salinity stress cultures decreased by 34,4%.
Keyword: bZIP1, LEC1, salinity stress, transcription factor, triacylglycerol

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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