Gore, Matthew (2013-08). Growth Rate of Marine Microalgal Species using Sodium Bicarbonate for Biofuels. Master's Thesis.
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 (CO_(2)) gas into the media to provide a carbon source for photosynthesis, but this can be very inefficient releasing most CO_(2) back into the atmosphere. This research began by investigating the effect of sodium bicarbonate (NaHCO_(3)) in the growth media as an alternative carbon source to bubbling CO_(2) into the cultures. The second part examined if NaHCO_(3) 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 NaHCO_(3) in modified seawater (f/2) media. To investigate effects of NaHCO_(3) on lipid accumulation, growth media cultures were divided into two -lipid phase? medias containing either 0.0g/L (non-boosted) or 10.0 g/L (boosted) NaHCO_(3) treatments. Culture densities were determined using spectrophotometry, which showed both all three species are able to successfully grow in media ameliorated with these high NaHCO_(3) concentrations.
Highest growth phase culture densities occurred in NaHCO_(3) 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 NaHCO_(3) 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.