Screening of microbial lipases and evalutaion of their potential to produce glycerides with high gamma linolenic acid concentration

Gamma-linolenic acid (GLA, 18:3, cis- 6,9,12-octadecatrienoic acid), an important compound in n-6 eicosanoid family biosynthesis, occurs in the lipids of a few plant and microbial sources. This study focused on the screening of microbial strains with suitable lipase activity for enrichment of GLA by selective hydrolysis of the borage oil (21.6 percent of GLA/total fatty acids). Firstly, 352 microrganisms were tested for their lipolytic capacity using screening techniques on agar plates containing borage oil, strains were then selected and screened for their activity (U/mg) using both submerged fermentation (SmF) and solid state fermentation (SSF). The rate of hydrolysis and the selective preference of these hydrolytic enzymes towards fatty acids, with a special focus on enrichment of GLA were studied and compared with those obtained by two commercially-available lipases. Only one of the lipases tested during this study displayed selectivity, discriminating the GLA during the hydrolysis reaction. Using the enzymatic extract from Geotrichum candidum as a biocatalyst of the reaction, it was possible to obtain a percentage of 41.7 percent of GLA in acylglycerols fraction when the borage oil was treated in a fixed-bed reactor for 24 hours at 30ºC.

Exclusión del ácido alfalinolénico de la dieta de la rata durante varias generaciones. I. Efecto en la reproducción y crecimiento postnatal / Exclusion of alpha-linolenic acid from diets for rats during several generations. I. Effect on reproduction and postnatal growth

The effects of a dietary alphalinolenic acid (18: 3w3) deficiency on reproduction and post natal growth in rats during 3 successive generations were studied. Female rats received respectively a diet with sunflower oil at 10 (deficient diet) or a diet with soya oil at 10 (control diet). The results showed that in our experimental conditions deficient diet affects: fecundity, fertility, post natal growth and cause a high rates of perinatal mortality from birth to post partum day 3: Perinatal mortality increased with successive gestation from 14.6 to 18.6 compared with the survival of control. The fatty acid composition of placenta phospholipids and milk lipids reflected the nature of the dietary oil. The possibility that 18: 3w3 might function in a way different from the EFA role of 18: 2w6 in reproduction at least in rats has been discussed.