Abstract-In this study, the growth of the microalgae, Isochrysis sp. under different illumination levels of natural sunlight was evaluated. Isochrysis sp. was cultured in f/2 media with five variations of illumination exposures. Each experimental setup was cultured in a 1 L cylindrical column with aeration provided by an air pump. Results showed that the best growth was exhibited when microalgae culture was exposed to 73.6% of illumination exposure with a light-dark cycle of 43.88-28.36s per height of column. Said culture also gave the highest CO 2 fixation rate of 0.541 g CO 2 /day. This proved that optimum illumination exposure is one of the most important factors towards improving microalgae growth rate and enhancing its' carbon fixation ability.

Carbon capture and storage (CCS) through biological approach has attracted much attention as global warming and climate change issue becomes a worldwide agenda. Energy production industry from coal in Malaysia produced 50.661 million metric tons of carbon dioxide in 2012, and the trend showed it will keep increasing year by year. CCS through biological approach can be done by microalgae which are versatile microorganism which perform photosynthesis process that can store CO2 in the biomass form. In this study, microalgae strains were isolated from the native environment nearby a coal-fired power plant, where samples were collected in different canal in which pre-treated flue gases are discharged. The microalgae strains were identified by both morphological and molecular approaches. Result from 18s rRNA gene sequencing showed that the isolated strains is Chlorella sp. with similarity 99% with Chlorella sp. SAG 211-18. The identified strains of microalgae then cultivated with three concentration of CO2 (ambient air, 1% and 5%) and the growth rate showed 0.4017 day -1 , 0.5752 day -1 and 0.4427 day -1respectively. Different concentration of CO2 (ambient air, 1% and 5%) showed that the isolated strains yielded 1.005gL -1 , 1.101gL -1 and 1.035gL -1 respectively. This study also showed that with different concentration of CO2, the sequestration rate is ranging from 1% to 4.3%.Keywords: microalgae, isolation, purification, DNA sequencing Abstrak Pemerangkapan dan penyimpanan karbon (CCS) melalui pendekatan biologi telah menarik minat pengkaji disebabkan masalah pemanasan dan perubahan iklim global. Pada tahun 2012 sahaja, Malaysia telah menghasilkan 50.661 juta ton metrik karbon dioksida hasil daripada penghasilan tenaga yang bersumberkan arang batu, dan tahun demi tahun penghasilan karbon dioksida dijangkakan akan terus meningkat. Pemerangkapan dan penyimpanan karbon melalui pendekatan biologi boleh dilakukan oleh mikroalga yang merupakan mikroorganisma unggul di mana ianya berupaya menjalankan proses fotosintesis dalam menukarkan karbon dioksida ke dalam bentuk biojisim. Dalam kajian ini, mikroalga dipencilkan daripada habitat asal yang merupakan terusan bagi air penyejuk untuk stesen janakuasa arang batu. Mikroalga yang diperoleh, dikenalpasti menggunakan kaedah pengecaman secara morfologi dan molekul. Hasil keputusan pengenal pastian molekul menggunakan kaedah penjujukan genom 18s rRNA mendapati, mikroalga yang berjaya dipencilkan adalah Chlorella sp. yang mempunyai persamaan sehingga 99% dengan Chlorella sp. SAG 211-18. Mikroalga yang telah menjalani proses identifikasi kemudiannya dikultur menggunakan 3 kepekatan karbon dioksida yang berbeza (CO2 pada udara persekitaran, CO2 1% dan CO2 5%) dan hasil menunjukkan kadar pertumbuhan masing-masing adalah 0.4017 hari -1 , 0.5752 hari -1 , dan 0.4427 hari -1 . Pada kepekatan CO2 yang berbeza (CO2 pada udara persekitaran, CO2 1% dan CO2 5%), hasil biojisim yang terkumpul daripada pengkulturan mikroalga masing-masing

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Abstract. Marine microalgae species was isolated and identified from its native condition of sea water discharge canals at the TNB Janamanjung Sdn Bhd's coal-fired power station. The species was expected to be a robust one based on the prevalent harsh upstream conditions and processes the survived ones endured. The isolation involves streaking-plating method as well as serial dilution and liquid media culture propagation. Morphological and molecular identification were both carried out before satisfactory identification of Chlorella sp. be made. This species was later mixed with marine Isochrysis sp. with varying volumetric proportions and cultured in five separate air-lift bubbling column photobioreactors, as part of the experiment to determine which optimum volumetric culture ratio is best to fix CO2 from the power plant. Results indicate that a more dominant ratio of Chlorella sp. 75% and Isochrysis sp. 25% by volume provide gives a better growth profile and indicates a better CO2 fixation rates.