Fatty acid biosynthesis during the life cycle ofDebaryomyces etchellsii

• Published in: Microbiology (Society for General Microbiology) Vol. 162; no. 7; pp. 1080 - 1090
• Main Authors: Arous, Fatma, Mechichi, Tahar, Nasri, Moncef, Aggelis, George
• Format: Journal Article
• Language: English
• Published: 01.07.2016
• Subjects: Debaryomyces
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.000298

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 ATPcitrate 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 super(+)-isocitrate dehydrogenase (NAD super(+)-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 super(+)-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.