The tolerance of cyanobacterium Cylindrospermopsis raciborskii to low-temperature photo-inhibition affected by the induction of polyunsaturated fatty acid synthesis.

Acyl-lipid desaturation introduces double bonds (unsaturated bonds) at specifically defined positions of fatty acids that are esterified to the glycerol backbone of membrane glycerolipids. Desaturation patterns of the glycerolipids of Cylindrospermopsis raciborskii, a filamentous cyanobacterium, were determined in cells grown at 35 degrees C and 25 degrees C. The lowering of the growth temperature from 35 degrees C to 25 degrees C resulted in a considerable accumulation of polyunsaturated octadecanoic fatty acids in all lipid classes. The tolerance to low-temperature photo-inhibition of the C. raciborskii cells grown at 25 degrees C and 35 degrees C was also compared. The lower growth temperature increased the tolerance of C. raciborskii cells. These results strengthen the importance of polyunsaturated glycerolipids in the tolerance to environmental stresses and may give a physiological explanation for the determinative role of C. raciborskii in algal blooming in Lake Balaton (Hungary).