title: Fatty acid biosynthesis during the life cycle of Debaryomyces etchellsii.
abstract: Fatty acid biosynthesis during the life cycle of the ascomycetous yeast Debaryomyces etchellsii cultivated on a non-fermentable substrate, i.e. glycerol, in nitrogen rich media (NRM) and nitrogen limited media (NLM) has been studied. Although considerable activities of key lipogenic enzymes, such as ATP citrate lyase (ACL) and malic enzyme (ME), were detected in vegetative cells during asexual proliferation (which occurred in the first growth stages in both NRM and NLM), lipid accumulation was restricted due to the high activities of NAD+-isocitrate dehydrogenase (NAD+-ICDH). A similar enzymatic profile has been found in ascii and free ascospores produced in NRM; thus lipid accumulation was low. On the contrary, very high activities of both ACL and ME and low activities of NAD+-ICDH were detected in ascii and free ascospores produced in NLM resulting in lipid accumulation. Neutral lipids (NL) were the predominant fraction of cellular lipids produced in vegetative cells and ascospores in both NRM and NLM. On the other hand, phospholipids (P) were the major polar lipids while glycolipids (G) were synthesized in low proportions. During transition from asexual to sexual phase, the percentage of NL increased with a significant decrease of P and, to a lesser extent, of G. High quantities of linoleic acid were found esterified in polar lipids, especially in P, during the vegetative stage of growth, while, with a few exceptions, during transition from asexual to sexual stage, linoleic acid concentration decreased markedly, mainly in P, while oleic acid concentration increased.
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia.|Unit of Microbiology, Department of Biology, University of Patras, Patras, Greece.
authors.forename: Fatma
authors.initials: F
authors.lastname: Arous
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia.
authors.forename: Tahar
authors.initials: T
authors.lastname: Mechichi
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia.
authors.forename: Moncef
authors.initials: M
authors.lastname: Nasri
authors.affiliation: Unit of Microbiology, Department of Biology, University of Patras, Patras, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Aggelis
mesh_terms: D001275:ATP Citrate (pro-S)-Lyase / Q000378:metabolism*; D005227:Fatty Acids / Q000096:biosynthesis*; D005990:Glycerol / Q000378:metabolism*; D006017:Glycolipids / Q000378:metabolism; D019787:Linoleic Acid / Q000378:metabolism; D050356:Lipid Metabolism / Q000502:physiology*; D008291:Malate Dehydrogenase / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D004718:Saccharomycetales / Q000254:growth & development / Q000378:metabolism*; D013170:Spores / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D006017:Glycolipids; D010743:Phospholipids; D019787:Linoleic Acid; D008291:Malate Dehydrogenase; C030574:malate dehydrogenase (decarboxylating); D001275:ATP Citrate (pro-S)-Lyase; D005990:Glycerol