Effect of the exogenous lipids of complex media on the fatty acid composition of mycelial microorganisms

The effect of exogenous lipid sources on the composition of fatty acids was studied in actinomycetes of the Streptomyces genus and in fungi belonging to the genera Blakeslea, Cunninghamella and Penicillium. The following sources of exogenous lipids were used: soybean and maize flour, sunflower by-products, chicken droppings, maize extract, yeast extract, peptone, sperm whale fat, sunflower and palm oil. The composition of fatty acids in total extracted lipids of the studied mycelial microorganisms was shown to reflect two processes: lipid synthesis de novo and assimilation of exogenous fatty acids. This fact ought to be taken into account both in the chemotaxonomic interpretation of fatty acid composition and in practical recommendations for the utilization of microbial lipids. It is of particular interest to study the physiological role of exogenous lipid metabolism in the cells of microorganisms.     

Stability of the fatty acid composition of actinomycetes

The stability of fatty acid composition of total extractable lipids was studied in Streptomyces cultures. The type of fatty acid composition typical of the Streptomyces genus remains stable when the actinomycetes were grown as submerged cultures in various synthetic media: saturated fatty acids with methyl branching in the chain predominated in all of the cases, and fatty acids with an uneven number of carbon atoms in the chain prevailed in most of the cases. Fatty acids with the anteiso structure predominated among the acids with a branched chain, amounting to more than a half of the latter and reaching sometimes 50% of the total fatty acid content. Methyl branchings were located in the anteiso position in fatty acids with an uneven number of carbon atoms, and in the iso position in fatty acids with an even number of carbons. Unsaturated fatty acids were found as a minor component.     

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Unusual fatty acid composition of cerebrosides from the filamentous soil fungus Mortierella alpina

The cerebrosides produced by the soil filamentous fungus Mortierella alpina strain KG-1/95 account for about 13% of the total polar lipids extractable from lyophilised cells with chloroform/methanol mixtures. By means of 1H NMR and (13)C NMR spectroscopy, matrix-assisted laser-desorption ionisation mass spectrometry, and chemical degradation experiment, they have been shown to be 1-O-beta-D-glucopyranosyl-2-N-(2'-D-hydroxyalkanoyl)-9-methylsphinga-4(E),8(E)-dienines, the fatty acid composition of which is unusual and consists of 2-hydroxytridecanoic (4%), 2-hydroxytetradecanoic (60%), 2-hydroxypentadecanoic (20%), and 2-hydroxyhexadecanoic (16%) acids.     

Synthesis of Biologically Active Lipids by the Fungus Mucor lusitanicus 306D Grown on Media with Various Composition

Growth and lipogenesis of the fungusMucor lusitanicus306D, producing -linoleic acid, was studied under various conditions of nitrogen and carbon nutrition. Media containing food-industry wastes, such as maize extract, molasses, and protein hydrolysate, were used. The content of -linoleic acid was higher when carbohydrates (glucose and molasses) were used as carbon sources and urea was used as a nitrogen source. At a high glucose concentration (100 g/l), fed batch cultivation ensured high contents of -linoleic acid in lipids (1 g/l). After extraction of lipids, the fungus biomass was 42% protein, containing all essential amino acids. A defatted biomass was shown to be effectively assimilated by minks.     

Effect of exogenous sterols on the growth and fatty acid composition of the oomycetePythium debaryanum

Exogenous ergosterol and cholesterol were found to affect the growth and lipogenesis of the oomycete fungusPythium debaryanum, which is unable to synthesize de novo steroid compounds. These sterols stimulated the growth of the fungus during its submerged cultivation in glucose-peptone medium. This was accompanied by the shortening of the lag phase, the lengthening of the period of active growth, and by a 3.7-or 4.3-fold increase in the maximum biomass in response to the addition of ergosterol or cholesterol, respectively. In the presence of ergosterol, the cellular content of polyenoic fatty acids increased, and the relative content of eicosapolyenoic fatty acids reached 31.4% of the total amount of fatty acids in cells. Conversely, cholesterol decreased the cellular content of polyenoic acids, and the relative content of eicosapolyenoic acids fell to 19.6% of the total amount of fatty acids. It may be inferred that exogenous sterols enhance the yield of pharmacologically active polyenoic acids because of the growth stimulation.     

Effect of Vitamin E and Its Analogues Having Various Molecular Structures on the Growth and Lipid Composition of Pythium debaryanum

The effect of exogenously added vitamin E and its synthetic analogues (the hydrophilic form of vitamin E and chromans C₁₃and C₁) at a concentration of 9.86 × 10^–5M on the growth, lipogenic activity, and the fatty acid composition of the eicosapolyenoic acid–synthesizing oomycete Pythium debaryanumwas studied. The effect was found to depend on the molecular structure of particular compounds. For instance, vitamin E and chroman C₁₃stimulated fungal growth, whereas chroman C₁inhibited it. The hydrophilic form of vitamin E enhanced the lipogenic activity of the oomycete. The studied compounds, which possess antioxidant activity, did not exert any noticeable effect on the content of eicosapolyenoic acids and the degree of the unsaturation of fungal lipids.