Screening of oleaginous microalgae and assessment of its oil producing capability

Abstract:

[Objective] The purposed of this study is to obtain some microalgae with fast growth and high oil producing ability. In addition, the effects of different culture methods on microalgae growth characteristics such as biomass, oil producing capacity and carbon consumption, and the adaptation of strains to pH were studied.[Methods] The method of phosphoric acid-vanillin reaction and Nile Red staining was used for obtaining some oleaginous microalgae. At the same time, different culture methods such as photoautotrophy, heterotrophy and mixotrophy, were studied by using GC-MS technique.[Results] Two strains of H and Z₈, which could produce 1.14±0.05 g/L and 1.33±0.10 g/L total lipid, respectively, were obtained. According to the results of morphological observations and 18S rDNA analysis, strains H and Z₈ had the highest homology with Chlorolobion braunii and Desmodesmus intermedius, so the strains were identified as Chlorolobion braunii H and Desmodesmus intermedius Z₈. Furthermore, H and Z₈ belonged to the growth coupling type based on the results of the kinetic model. There was no significant difference in the total lipid and biomass between H and Z₈ when the pH value was between 6.0 and 9.0 (P<0.05). The percentage of C16 and C18 fatty acids in total fatty acid from the strains H and Z₈ was more than 90%. The biomass from mixotrophy was better than heterotrophy, but it was more conducive to lipid accumulation under heterotrophic conditions. Furthermore, the strains of H and Z₈ have a wide pH adaptability.[Conclusion] These results indicate that the two strains are excellent potential lipid-producing strains.