| Abstract: | With additional research on species characteristics and continued work towards cost effective production methods, algae are viewed as a possible alternative biofuel crop to current feedstocks such as corn. Current open pond production methods involve bubbling carbon dioxide (CO₂) gas into the media to provide a carbon source for photosynthesis, but this can be very inefficient releasing most CO₂ back into the atmosphere. This research began by investigating the effect of sodium bicarbonate (NaHCO₃) in the growth media as an alternative carbon source to bubbling CO₂ into the cultures. The second part examined if NaHCO₃ could act as a lipid trigger in higher (10.0 g/L) concentrations. The microalgae species Dunaliella tertiolecta (Chlorophyta), Mayamaea spp. (Baciallariophyta) and Synechoccocus sp. (Cyanophyta) were grown with 0.0 g/L, 0.5g/L, 1.0 g/L, 2.0 g/L and 5.0 g/L dissolved NaHCO₃ in modified seawater (f/2) media. To investigate effects of NaHCO₃ on lipid accumulation, growth media cultures were divided into two - lipid phasell medias containing either 0.0g/L (non-boosted) or 10.0 g/L (boosted) NaHCO₃ treatments. Culture densities were determined using spectrophotometry, which showed both all three species are able to successfully grow in media ameliorated with these high NaHCO₃ concentrations. Highest growth phase culture densities occurred in NaHCO₃ concentrations of 2.0 g/L for D. tertiolecta and Mayamaea spp., and the 5.0 g/L treatment for Synechoccocus sp. Highest growth rates occurred in the 5.0 g/L NaHCO₃ concentration treatments for D. tertiolecta, Mayamaea spp., and Synechoccocus sp. (0.205 d-1 ±0.010, 0.119 d-1 ±0.004, and 0.372 d-1 ±0.003 respectively). As a lipid accumulation trigger two of the three species (D. tertiolecta and Mayamaea spp) had their highest end day oil indices in a 10.0 g/L treatment. Highest oil indices occurred in boosted 5.0 g/L Dunaliella tertiolecta and 2.0 g/L Mayamaea spp. (13136 ± 895 and 62844 ± 8080 respectively (relative units)). The results obtained indicate NaHCO₃ could be used as a photosynthetic carbon source for growth in all three species and a lipid trigger for D. tertiolecta and Mayamaea spp. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151333 |
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