Fatty acid profile of the edible filamentous cyanobacterium Nostoc flagelliforme at different temperatures and developmental stages in liquid suspension culture

The fatty acid profile of Nostoc flagelliforme (strains FACHB838 and CCAP1453/33), an edible terrestrial cyanobacterium, at different temperatures (i.e., 15, 20, 25 and 30 °C) and developmental stages (hormogonia, filaments, seriate and aseriate) in liquid suspension culture was investigated. The cyanobacterial species could be classified as Type IIB according to the existing taxonomic system based on fatty acid profiling, due to the presence of C18:3 and the absence of C16:2 and C16:3 fatty acids. Within the temperature range investigated, the content of C18:3n3 increased at the expense of C18:2n3 as temperature decreased, while the fatty acid suites remained unchanged. The degree of fatty acid unsaturation also increased with decreasing temperature, with the highest being 1.28 and 1.37 at 15 °C for the strains FACHB838 and CCAP1453/33, respectively. With respect to the effect of developmental stages, there was a slight variation in fatty acids composition and contents in the two strains without changing the fatty acid suite. At the aseriate stage at 25 °C, the highest C18 fatty acid proportion amounted to 63.17 and 65.08% and the degree of fatty acid unsaturation peaked at 1.32 and 1.31 in the strains FACHB838 and CCAP1453/33, respectively, indicating more long chain unsaturated fatty acids were accumulated at this stage.