Production of metabolites with antioxidant and emulsifying properties by antarctic strain Sporobolomyces salmonicolor AL1.

The Sporobolomyces salmonicolor AL(1) Antarctic strain was cultivated and two bioproducts were obtained: exopolysaccharide and biomass. The biologically active substances ergosterol, torularhodin, torulene, ß-carotene and CoQ(10) were extracted from the biomass and were quantified as follows: ergosterol 5.2 ± 0.2 mg/g, torularhodin 458.3 ± 24.5 µg/g, torulene 273.7 ± 14.5 µg/g, ß-carotene 129.2 ± 7.3 µg/g and coenzyme Q(10) (CoQ(10)) 236.1 ± 12.1 µg/g. Their antioxidant activity was estimated according to the cathode voltammetry method. The most pronounced antioxidant activity (according to trolox) was exhibited by ß-carotene 3.78, followed by CoQ(10) 3.60, both of them being the main contributors to the total extract activity of 3.19. The biologically active metabolites in combination with exoglucomannan as emulsifier were used for the creation of model emulsion systems characterised by great stability. The absorption of UVA rays by the model emulsions was studied.

Synthesis and characterization of an exopolysaccharide by antarctic yeast strain Cryptococcus laurentii AL100.

An exopolysaccharide-producing Antarctic yeast strain was selected and identified as Cryptococcus laurentii AL100. The physiological properties of the strain and its ability to utilize and biotransform different carbon sources (pentoses, hexoses, and oligosaccharides) into exopolysaccharide and biomass were investigated. Sucrose was chosen as a suitable and accessible carbon source. The biosynthetic capacity of the strain was studied in its dynamics at different sucrose concentrations (20, 30, 40, and 50 g/L) and temperatures (22 and 24 °C). The maximum biopolymer quantity of 6.4 g/L was obtained at 40 g/L of sucrose, 22 °C temperature and 96-h fermentation duration. The newly synthesized microbial carbohydrate was a heteropolysaccharide having the following monosaccharide composition: arabinose, 61.1%; mannose, 15.0%; glucose, 12.0%; galactose, 5.9%; and rhamnose, 2.8%. It was characterized by polydispersity of the polymer molecule, 60% of it having molecular mass of 4200 Da. The exopolysaccharide demonstrated good emulsifying and stabilizing properties with regard to oil/water emulsions and a pronounced synergistic effect with other hydrocolloids such as xanthan gum, guar gum, and alginate.

Synthesis of coenzyme Q10 and beta-carotene by yeasts isolated from antarctic soil and lichen in response to ultraviolet and visible radiations.

The effect of different doses of visible (Vis), ultraviolet-capital A, Cyrillic (UVA), and mixed light (UVA + Vis) upon coenzyme Q(10) (CoQ(10)) and beta-carotene synthesis and biomass yield by the Sporobolomyces salmonicolor AL(1), Cryptococcus albidus AS(55), Cryptococcus laurentii AS(56), and C. laurentii AS(58) strains isolated from Antarctic samples was investigated. The beta-carotene concentration in the red strain biomass increased by 52% under irradiation with 11 J/cm(2) Vis, and the CoQ(10) concentration rose by 37% in relation to the control quantity obtained through dark cultivation. Under irradiation with 6 J/cm(2) UVA, the S. salmonicolor AL(1) strain synthesized 15% more beta-carotene; C. albidus AS(55), 22%; C. laurentii AS(56), 44%; and C. laurentii AS(58), 35% in relation to the control quantity. Irradiation with a low UVcapital A, Cyrillic + Vis dose significantly stimulated beta-carotene biosynthesis by the strains of the Cryptococcus genus (87%, 138%, and 100%), whereas S. salmonicolor AL(1) increased the beta-carotene content to a smaller degree (55%). Higher doses of all three irradiation types inhibited beta-carotene accumulation. Vis suppressed CoQ(10) biosynthesis in the Cryptococcus strains, whereas UVcapital A, Cyrillic and UVcapital A, Cyrillic + Vis inhibited it in all four strains. The S. salmonicolor AL(1) strain pre-treated with 0.02 J/cm(2) UVA synthesized twice as much CoQ(10) and beta-carotene when cultivated in the presence of Vis light in an 11-J/cm(2) dose.