GROWTH RATE AND BIOCHEMICAL CHARACTERIZATION OF CHLORELLA PYRENOIDOSA CULTIVATED IN SUGARCANE VINASSE MEDIUM

Chlorella pyrenoidosa is a microalgae species that contains proteins, carbohydrates, amino acids, carotenoids, vitamins, and minerals. Due to its compounds, the researchers have attempted to make bioethanol using C. pyrenoidosa through a biorefinery approach. However, the ratio of bioethanol production towards the raw material needs of C. pyrenoidosa is still small because of its low carbohydrate content. Thus, in this research, vinasse is used as its growth medium to increase the carbohydrate content. The research objective is to study the effect of vinasse volume ratio and nutrient addition towards the size, optical density, carbohydrate composition, growth rate of the C. pyrenoidosa, and its evaluation as a biorefinery raw material. C. pyrenoidosa was cultivated in freshwater and vinasse (20 and 30% v/v) in mini ponds, equipped with lighting using 3280 lumens lamp, aeration with air, and Guillard as nutrient. In vinasse, the cultivation was done with and without periodic nutrient additions. The microalgae cell size was increased if cultivated in vinasse and given Guillard addition, which is 3.0-3.6 mm (in freshwater), 4.1-8.6 mm (in vinasse with nutrient every 2 days), 4.8-6.3 mm (in vinasse without nutrient every 2 days). The microalgae carbohydrate composition cultivated in vinasse was sharply increased compared to in freshwater. Thus, C. pyrenoidosa cultivated in vinasse is very potential for bioethanol production. Specific growth of C. pyrenoidosa in vinasse with nutrient is faster (0.087 day-1) than without nutrient (0.023 day-1) and in freshwater (0.062 day-1). Cultivated C. pyrenoidosa contains proteins, lipids, and carbohydrates, so it has the potential of becoming a biorefinery raw material.