The continent of Antarctica, as a combination of constantly low temperatures, strong winds, short summer season, and high solar radiation, is a highly extreme habitat suggesting appropriate conditions for growth of psychrophilic microorganisms. Five psychrophilic yeast strains were isolated from the samples taken from the region of the Bulgarian Base on Livingston Island, Antarctica: Cryptococcus laurentii AL 65 , Sporobolomyces salmonicolor AL 36 , Debaryomyces hansenii, Leucosporidium scotii and Rhodotorula glutinis, and their biomass yield and exopolysaccharides production were investigated. Best growth was observed for L. scotii and C. laurentii AL 65 , with 7.5 and 6.0 g/L biomass, respectively, and highest exopolysaccharide yield was established for L. scotii. Metabolic profiling revealed phylogenetically based diversity in the identified metabolic profiles. The proton nuclear magnetic resonance (1 H NMR) spectroscopy analyses of compounds extracted from the biomass of the strains revealed significant differences in the metabolites between individual yeast strains in our investigation including: among the amino acids alanine, valine, threonine, leucine and tyrosine; some organic acids such as gamma-aminobutyric acid, acetic acid, formic acid and others. Glucose was identified in all investigated strains. The highest diversity of compounds was observed in D. hansenii strain, division Ascomycota. The main compounds in the metabolic profile of Basidiomycota strains were sugars. The statistical analysis revealed significant differences in the studied metabolites among the yeast strains. This result suggests that, together with 16S rRNA gene and enzyme gene analyses, metabolite profiling could be also used as a marker for a phylogenetic distance in fungi evolution.

BACKGROUND Pollution by heavy metals poses serious environmental problems and is dangerous to human health, so considerable attention has been given to methods for their removal from industrial effluents. The need for highly effective biosorbents able to remove heavy metals from waste waters, even at the low concentrations which are still toxic for living organisms in ecosystems, is a topical problem. RESULTS In the present study, psychrophilic yeast strain Cryptococcus laurentii (AL65) was used to explore its potential for biosorption of metal ions. The accumulation of biomass was followed continuously in the context of bioreactor cultivation. An adsorption experiment of caustic pretreated biomass was conducted in batch mode with synthetic mixed solution in the pH range 4.7–7.0, and ion concentrations of individual metals were simultaneously determined by inductively coupled plasma ‐ optical emission spectrometry (ICP‐OES). Biosorption abilities were determined for 15 elements: the total amount of adsorbed ions was 68 mg g−1 dry biomass for 10 mg L−1 initial concentration of each element in the solution, and 113 mg g−1 for 20 mg L−1. The highest adsorption capacity was observed in the 20 mg L−1 solution for aluminium, chromium, indium, gallium, iron and bismuth in the range 12–16 mg g−1 dry biomass at an optimal pH of ≈5. CONCLUSION The results on the biosorption ability of Antarctic producer Cryptococcus laurentii (AL65) can be used in the optimization of technological processes for the removal of heavy metals from aqueous solutions. © 2019 Society of Chemical Industry

The 1 H and 13 C NMR spectra of the neo-clerodane diterpenoid scutecyprin were completely assigned by using a combination of 2D NMR experiments, which included 1 H-1 H COSY, HSQC, HMBC and NOESY sequences.

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