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 Analysis of Lipid Biosynthesis-Related bZIP1 and LEC1 Ortholog Genes in Chlorella vulgaris Cultures Under Nitrogen Deficiency Conditions, Expression Analysis of Lipid Biosynthesis-Related bZIP1 and LEC1 Ortholog Genes in Chlorella vulgaris Cultures Under Nitrogen Deficiency Conditions
Abstrak: Microalgae can produce energy-rich compounds, especially triacylglycerol, for biofuel production. This study aims to analyze the expression of lipid biosynthesis-related bZIP1 and LEC1 ortholog genes in the culture of Chlorella vulgaris under optimum and nitrogen-deficiency conditions and to identify the microalgae isolates through molecular approach. The C. vulgaris samples were cultured and subjected to nitrogen-deficiency treatment in NaNO3 compound with a control-to-treatment ratio 4:1 and final concentrations of 100 and 25 mg/L. Cell harvesting was performed on exponential phase based on the cell growth curve calculated using haemacytometer. Sequencing techniques confirmed the taxonomic status of microalgae isolates on 18S rRNA gene fragments. The orthologous genes were analyzed in the GeneBank database using the BLAST algorithm based on the similarity of protein sequences (BLASTp and tBLASTn). Total RNA isolation, cDNA synthesis, and qRT-PCR performed the gene expression analysis. Cell density calculation results showed that nitrogen-deficiency decreased the C. vulgaris growth. Sequence analysis of the 18S rRNA gene fragment revealed similarity with Chlorella. The qRT-PCR analysis results indicate a significant upregulation of the LEC1 ortholog gene by 2-fold compared to the control. Differently, the upregulation of the bZIP1 ortholog gene is not statistically significant, showing a 1.5-fold increase compared to the control.
Keyword: nitrogen-deficiency, bZIP1, LEC1, qRT-PCR

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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