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A preliminary research in the field of environmental biotechnology to the production of biofuel from the tropical microalga consortium consisting of Chlorella vulgaris and Closterium sp have been done. Microalga cultivation in batch culture are controlled at temperature of 25°C, PH 6, aeration of 1 ml/sec, and lights of 4000 lux. Nutrient sources utilize artificial Provasoli Heamatococcus Media which consist of micro and macro nutrients. Analysis of bioethanol from microalga start with finding the maximum starch production from wet weight of biomass, dried weight of biomass, and at hydrolysis. Hydrolysis is proceeded by adding HCL 1 Molar as much as 0.04 grams of dried weight of biomass. The analysis of starch is proceeded by nelson samogy method by adding alkali and pre reaction arsenomolibdat. Absorbent is measured through the wave length 540 nm by spectrofotometre. The average of dried weight biomass is 0,8 grams/liter. Research reveal that the highest starch production is occured in microalga consortium at hydrolysis process and produces starch of 88.31% (v/v). The two types of tropical microalgae have a potential as solid compound of bioethanol.

This research was aimed to obtain algae biofuels as an alternative energy which comes from tropical microalgae biomass Chlorella sorokiniana and Closterium sp. The cultivation was performed at a controlled room in batch culture photobioreactor, temperature 27°C, pH 6, aeration with air flow rate of 150 mL/sec, and light intensity at 2400 lux. These nutrient sources used artificial PHM with KNO3 variation as a nitrogen source of 0 grams; 0.25 grams; 0.5 grams; 1 gram. The research involved microalgae lipid extraction with Blight & Dyer method and also carried out support of alcohol, chloroform and distilled water (1:1:1) with optimum temperature 30oC. Oil yields that obtained were analyzed with Gas Chromatography Mass Spectrometry (GC-MS) method, dry weight with a gravimetric method and cell density with spectrophotometry. The result showed that the reduction of KNO3 materials (0,25 gr) can produce biomass and highest total lipid content at 0,41 g/L and 20,31 %/(w/w). The results showed that KNO3 decreased the amount of biomass which was not significant but the total lipid content of microalgae was increased. Lipid content and fatty acids extracted from Blight & Dyer showed oil content that could potentially be the raw material of biodiesel.