A new species of reddish-orange pigment-producing microalga was isolated from a shallow pond in tropical Taiwan. Morphological and molecular evidence including meridional ribs on the cell wall, pigment production, and 18S rDNA sequence analysis suggest that this microalga is a species in the genus Coelastrella. Salt stress accelerated biosynthesis of the reddish-orange pigments, and large quantity of oil accumulated as the cells stressed under nutrient deficiency. This microalga could sustain 45 ¢XC for more than 8 hours indicated by the stability of its chlorophylls, which is a necessary trait for large scale outdoor cultivation using photobioreactors in tropical areas. The reddish-orange pigments could be separated into many fractions by HPLC, and signals from carotenoids were detected in a few fractions using NMR, suggesting these pigments may function as antioxidants among other roles.

Microalgae are one of the oldest types of lifeforms on this planet and dead algae are one source for the oil that we extract from the ground. This oil has a major part in the technology advances of humanity, to levels unimaginable not long ago. Unfortunately, this oil is one of the major reasons for the global warming and other environmental issues caused by humans. Therefore, much effort is made on new technologies to decrease the use of fossil oil and other fossil material in favor for so called renewable sources. In this work focus is on production of biomass that can be used for processing to other bulk materials, mainly chemicals. This is also a highly potential market, the amount of materials derived from fossil sources are at least 422 million metric tons per year. The issue though is that the production costs for algae are still fairly high and can’t compete with the market price of fossil raw materials. Two algae species, Scenedesmus obliquus and Coelastrella sp., were cultivated in 6 pilot size ponds (500 L) and the results were compared to a lab experiment (0.5 L). The lab experiment was earlier performed by the author’s supervisors with the same species. The algae in the ponds were cultivated outdoor with flue gas in semi-closed ponds and the resulting biomass was allowed to sediment spontaneously. Scenedesmus obliquus was successfully cultivated in the pilot, but the system was not suitable for cultivation of Coelastrella sp. The main aim of this work was to evaluate if it is possible to predict the amount of biomass produced in the pilot cultivation based on the results from the previously performed lab cultivation. The conclusion based on the results in this work is that it not possible to predict the biomass production in the pilot based on lab experiments. The properties and behavior of different algae species can be very different in different systems, and the setups in this study differed too much. However, the results indicate that the pilot system has a high efficiency and can maintain a monoculture outdoors for at least 18 days as well as that the supply of flue gas highly affects the growth of the algae Scenedesmus obliquus.