People have been searching toward to biofuel as a prominent alternative to replace oil fuel. Microalgae biomass, specifically from the genus Synechococcus, has been used as the biofuel’s feedstock as it’s able to grow faster than the other groups at cyanobacteria. Strains being used were isolated from Ciseeng hot spring (HS-7) and Rawa Danau Banten hot spring (HS-9). The intensity of aeration (IA) were given as high (330 bubbles/min) and low (220 bubbles/min) to understand its influence on feedstock growth. Change in growth was observed microscopically using direct methods over fourteen days. At the end of the experiment, result demonstrate that high IA gaves rise to Synechococcus biomass density at 125,21 × 106 cell/ml and 100,63 × 106 cell/ml for HS-7 & HS-9 respectively. Meanwhile, low IA gaves rise to Synechococcus biomass density at 21,7 × 106 cell/ml and 10,61 × 106 cell/ml for HS-7 & HS-9 accordingly. Positive trend also follows the growth at Synechococcus biomass with high IA, but did not apply to the system with low IA. The difference in biomass production occurred because of discrepancies in cell and nutrient distribution inside the photobioreactor system. Therefore, it implies that proper controlling of IA would affect the yielding of feedstock for producing biofuels.

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Indonesia known as a hotspot of biodiversity, including cyanobacteria biodiversity. One member of cyanobacteria (prokaryotic algae) is Leptolyngbya. Leptolyngbya HS-16 is an isolate that had been isolated from hot spring in Red Crater of Gunung Pancar, Sentul, Bogor. As mats-producing microalgae, this strain is a very promising source of Biofuel. Biofuel can be extracted from lipid of microalgal biomass. Bioreactor is a method to encourage the growth of microalgal biomass. To get a best result in growth, agitation must be done, to make sure every single cell of microalgae gets the adequate nutrition. The aeration on simple photobioreactors is set to high and low intensity. The high intensity of aerations average amount are 191 bubble/min, while the low intensity one are 117 bubble/min, with a device that could produce smaller bubble size to reduce the aeration-agitation effect. The research was done to acknowledge the effect of aeration intensity to Leptolygnbya HS-16.