Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XIX
Written by Diana GROPOŞILĂ-CONSTANTINESCU, Ovidiu POPA, Narcisa BĂBEANU, Gabriela MĂRGĂRIT
Among hundreds species of yeasts and molds, only few are able to accumulate more than 25% lipids. The aim of our experiments was to select microorganisms with high potential of lipids producing (“oleaginous” microorganisms). Several strains of yeasts and molds were tested in order to determine their ability to produce and accumulate lipids. The strains were cultivated in Petri dishes on specific media. Evaluation of lipid accumulation was achieved by microscopic observations, through Sudan Black B dyeing technique. Preliminary tests in order to determine the capacity of lipid production were made by Soxhlet extraction, after batch fermentations on liquid media. The results showed that five strains of yeasts and molds, Yarrowia lipolytica, Hansenula anomala, Sacharomyces cerevisiae, Aspergillus niger and Trichoderma viridae, were the best lipid producers, which accumulated up to 40% of lipids in dry biomass. One of the key factors in achieving an economically attractive bioprocess is the conversion yield of the substrate into lipids. In this case, yeasts are superior to fungi with a conversion yield over 20%, in comparison with less than 18% for molds. Given these considerations, additional experiments will be conducted to optimize the conditions of lipid production with Yarrowia lipolytica.
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