Temperature-independent and -dependent expression of desaturase genes in filamentous cyanobacterium Spirulina platensis strain C1 (Arthrospira sp. PCC 9438)

Abstract

The alteration of the degree of unsaturated fatty acids in membrane lipids has been shown to be a key mechanism in the tolerance to temperature stress of living organisms. The step that most influences the physiology of membranes has been proposed to be the amount of di-unsaturated fatty acids in membrane lipids. In this study, we found that the desaturation of fatty acid to yield the di-unsaturated fatty acid 18:2(9,12), in Spirulina platensis strain C1, was not regulated by temperature. As shown by the fatty acid composition and gene expression patterns, the levels of 18:1(9) and 18:2(9,12) remained almost constant either when the cells were grown at 35³C (normal growth temperature) or 22 and 40³C. The expression of desC (v9) and desA (v12) genes, which are responsible for the introduction of first and second double bonds into fatty acids, respectively, was not affected by the temperature shift from 35 to 22³C or to 40³C. Only the expression and mRNA stability of the desD gene (v6) that is responsible for the introduction of a third double bond into fatty acids were enhanced by a temperature shift from 35 to 22³C, but not the shift from 35 to 40³C. The increase in the level of desD mRNA elevated the desaturation of fatty acid from 18:2(9,12) to 18:3(6,9,12) at 22³C. However, the increased level of 18:3(6,9,12) was observed after 36 h of incubation at 22³C, indicating a slow response to temperature of fatty acid desaturation in this cyanobacterium. These findings suggest that the desaturation of fatty acids might not be a key mechanism in the response to the temperature change of S. platensis strain C1. ß

Influence of desalinator wastewater for the cultivation of <i>Arthrospira platensis</i>. Fatty acids profile

“…However, these values are lower than those reported by Deshnium et al (2000), who found contents of 20% when cultivating A. platensis in Zarrouk medium at 35°C, and Xue et al (2002) who analyzed dehydrated Arthrospira. On the other hand, Tokus , oglu and Ünal (2003) Docosahexaenoic acid (C22:6) occurred only in the biomass cultivated in SWM.…”

Perfil de ácidos graxos de microalgas cultivadas com dióxido de carbono

“…Segundo Hoshida et al (2005), em cultivos com Nannochloropsis sp., o acúmulo de EPA foi incrementado pela elevação da concentração de CO 2 de 0,037 a 2,0%.…”

Combined effect of temperature and light intensity on growth and extracellular polymeric substance production by the cyanobacterium Arthrospira platensis

“…In 1981, the United States Food and Drug Administration (FDA) decided that A. platensis could legally be sold as a food supplement because of its ability to produce large quantities of valuable products such as phycocyanin (Estrada et al 2001) and ω-6 and ω-3 polyunsaturated fatty acids (Deshnium et al 2000;Cohen et al 1993). This cyanobacterium can also release soluble material known as extracellular polymeric substances (EPS) into the culture medium (Tseng and Zhao 1994;Nicolaus et al 1999).…”