Studies on the co-metabolism of glucose and glycerol in the fungus Umbelopsis isabellina

Poly-Unsaturated Fatty Acids (PUFAs) from Cunninghamella elegans Grown on Glycerol Induce Cell Death and Increase Intracellular Reactive Oxygen Species

“…According to the contemporary literature, glycerol in general is not a very appropriate substate amenable to be used for most fungi (higher or lower) due to its poor uptake regulation. For most higher or lower fungi, growth and lipid production on glucose is significantly better than that on glycerol; for instance, the growth of fungi of the genera Aspergillus, Lentinula, Mucor, Morchella, etc., on glycerol was accompanied by lower dry biomass production compared to growth on glucose [27,29,42,43,49]. This is not the case with the growth of oleaginous yeasts (i.e., Rhodosporidium toruloides, Yarrowia lipolytica, Debaryomyces prosopidis, etc.)…”

“…This agrees with the results reported for several oleaginous Zygomycetes (e.g., Mucor sp., Rhizomucor pusillus, Umbelopsis isabellina, C. echinulata, etc.) cultivated on renewable sugar-or glycerol-based substrates under nitrogen-limited conditions [8,27,42,45,52]. Moreover, as mentioned in the previous paragraphs, Zygomycetes in general produce inside their cellular lipids mostly the γisomer of the FA linolenic (the GLA; ∆6,9,12 C18:3, belonging to the ω-6 series) instead of the αone (viz.…”

“…Prior to any other analysis being performed, immediately after performing the selection of the flask that would constitute the experimental point, the dissolved oxygen (DO) concentration was quantitatively determined using a selective electrode (OXI 96, B-SET, Weilheim, Germany), according to a previously published procedure [26]. Oxygen saturation remained in values >30% (v/v) during all growth phases for both microbial substrates used (glucose and glycerol), indicating that the trials had been carried out under fully aerobic conditions [26,27], as it is already an established knowledge that an important prerequisite for sufficient de novo lipid production process is growth under sufficiently aerobic conditions into the growth medium [1][2][3]5]. Immediately after removing the flask from the incubator, the pH value of the culture medium was measured for all experimental points and all trials, by using a selective Jenway 3020 pH meter (Jenway, London, UK).…”

“…1 cellulose filter paper (diameter: 45 mm, thickness: 180 µm, fiber cut-off: 11 µm) and were extensively washed with distilled water. Total dry cell weight (TDCW) was determined through measurement of the dry matter of mycelia after placement of the wet biomass at T = 80 ± 2 • C until a constant weight was achieved (most usually this happened within 30 ± 4 h) [27]. Total cellular lipid (L, g/L) was extracted from the dried mycelia with a mixture of chloroform/methanol 2/1 (v/v) according to the procedure explicitly described by Sarantou et al in 2021 [28], and was weighted after evaporation of the solvent.…”

“…Total cellular lipid (L, g/L) was extracted from the dried mycelia with a mixture of chloroform/methanol 2/1 (v/v) according to the procedure explicitly described by Sarantou et al in 2021 [28], and was weighted after evaporation of the solvent. Lipids were converted to methyl-esters in a two-step reaction using consecutively methanolic sodium and hydrochloric methanol, and the produced fatty acid methyl esters were analyzed by the means of GLC according to Dritsas and Aggelis [27]. Finally, glycerol and glucose were quantitatively determined with the aid of High Performance Liquid Chromatography (HPLC) analysis, as indicated in detail in André et al [29].…”