Libération des acides gras par autolyse enzymatique des triglycérides des graines oléoprotéagineuses

Abstract

Fatty acids produced by chemical hydrolysis of the plant lipids are starting materials for the industry of biocarburants, biolubricants, plastics, detergents and also as adjuvants in commercial preparation of herbicides. However the actual process used for industrial production of fatty acids from plant lipids are highly pollute and energy consuming. In this work we tested a new process of fatty acid production involving genetically modified plants. Using tobacco as a model plants we introduced a genetic construct containing a lipase gene (from the yeast Geotrichum candidum) under the control of a seed specific promoter (promotor AtEm1) from Arabidopsis thaliana. This promotor would allow the expression of the lipase gene in the embryo axis of the seeds while lipids reserves accumulate in the oilbodies in the cotyledon. Thus in vivo the lipids would be separated from the enzyme by tissular compartmentation. Upon grinding it is assumed that contact between the lipase and the lipids would result in fatty acid production. Several transformants were produced by Agrobacterium tumefaciens infection, some of them expressing the lipase gene, Three of them (clones 2, 19 and 43) showed a significant lipase activity and were retained for future researches. When seeds of clone 43 were ground in a buffer, fatty acids were produced as it was postulated. However the fatty acid yield was low and some transformants showed a defect in compartmentation of the lipase accumulation. New constructs involving modification of the AtEm1 promotor or other new promoters are planed before introduction of the genetic construct into agronomically interesting plants such as rape and/or sunflower. Moreover improvements of the enzymatic reaction conditions are needed. The reaction could occurred inside a multifunctional reactor performing both lipid hydrolysis and rapid extraction of the produced fatty acids.