Ekspresi Gen Ortolog bZIP1 dan LEC1 Terkait Biosintesis Lipid pad Chlorella vulgaris di bawah Kondisi Defisiensi Nitrogen

Abstract

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.