Galhano, VictorSantos, H.Geraldes, Ana MariaFigueiredo, Daniela R.Crespí, AntónioGomes-Laranjo, JoséPeixoto, Francisco P.2011-03-312011-03-312010Galhano, V.; Santos, H.; Geraldes, A.M.; Figueiredo, D.R., Crespi, A.; Gomes-Laranjo, J.; Peixoto, F (2010). Fatty acid characterization of cyanobacterial strains isolated from Vela lake and Mondego river rice fields. In XV Congresso Ibérico de Limnologia. Ponta Delgadahttp://hdl.handle.net/10198/3851t is know that particular groups of cyanobacteria are characterized by particular lipid patterns that can be used as their biological markers. The present study examined the fatty acid composition of nostocacean heterocystous cyanobacterial strains isolated from Central-western Portuguese freshwater shallow water bodies, namely Vela Lake and rice fields from Mondego River Basin. Morphological characterization showed that strains from Vela Lake belonged to Aphanizomenon gracile (strains uADFA16 and uADFA18), Aphanizomenon flos-aquae (strain uADFA15) and Anabaena cf. solitaria (strain uADFA14) species, whereas rice field strains belonged to Anabaena cylindrica (strain uTAD_A212) and Nostoc muscorum (strain uTAD_N213). generally, biochemical characterization inferred from lipid analysis showed that the predominant fatty acid methyl esters (FAMEs) in the lipids of the strains were palmitic, oleic and α-linolenic, with trace amounts of myristic and C20 polyunsaturated FAMEs. Palmitic acid contente in uADFA16 was 2.4 and 2.6 times higher than in uTAD_A212 and uTAD_N213, respectively. Surprisingly, the two Aph. gracile strains had different FAME composition and the high concentration of myristic acid in uADFA14 could be indicative of some hepatoxicity. The comparison of quantitative and qualitative FAME composition of the strains isolated from the two different habitats could explain the close chemotaxonomic relationship between the strains uTAD_A212 and uTAD_N213, both isolated from rice paddies. The same approach could be applied to the strains uADFA14 and uADFA18 isolated from the Vela Lake ecosystem. Principal component statistical analysis of variability of fatty acids belonging to the six genera is reported. To our knowledge, there is almost no information about lipid composition in freshwater cyanobacterial species living in different habitats in Portugal. Therefore, this limnological study is a contribution to our investigation on diazotrophic cyanobacteria in the framework of a comprehensive colaboration program concerning the taxonomy, phylogenetic relationships and toxicological effects of pesticides and other xenobiotics on freshwater cyanobacteria.engconference object