Characterization of a Robust and pH-Stable Tannase from Mangrove-Derived Yeast Rhodosporidium diobovatum Q95

Tannase plays a crucial role in many fields, such as the pharmaceutical industry, beverage processing, and brewing. Although many tannases derived from bacteria and fungi have been thoroughly studied, those with good pH stabilities are still less reported. In this work, a mangrove-derived yeast strain Rhodosporidium diobovatum Q95, capable of efficiently degrading tannin, was screened to induce tannase, which exhibited an activity of up to 26.4 U/mL after 48 h cultivation in the presence of 15 g/L tannic acid. The tannase coding gene TANRD was cloned and expressed in Yarrowia lipolytica. The activity of recombinant tannase (named TanRd) was as high as 27.3 U/mL. TanRd was purified by chromatography and analysed by SDS-PAGE, showing a molecular weight of 75.1 kDa. The specific activity of TanRd towards tannic acid was 676.4 U/mg. Its highest activity was obtained at 40 °C, with more than 70% of the activity observed at 25–60 °C. Furthermore, it possessed at least 60% of the activity in a broad pH range of 2.5–6.5. Notably, TanRd was excellently stable at a pH range from 3.0 to 8.0; over 65% of its maximum activity remained after incubation. Besides, the broad substrate specificity of TanRd to esters of gallic acid has attracted wide attention. In view of the above, tannase resources were developed from mangrove-derived yeasts for the first time in this study. This tannase can become a promising material in tannin biodegradation and gallic acid production.

Lipid and β-Carotene Production by Rhodosporidium diobovatum Cultured with Different Carbon to Nitrogen Ratios

Background: In food industry, carotenoids are used as food colorants conferring yellow to red color. This research was designed to study on lipid and β-carotene production by Rhodosporidium diobovatum cultured with different Carbon to Nitrogen (C/N) ratios. Methods: R. diobovatum was cultured in a medium containing 40 g/l glucose (as the carbon source) and different C/N ratios (20, 50, and 80), which were established by adding different amounts of (NH4)2SO4 (3.78, 1.51, and 0.94 g/l) as the source of nitrogen. High performance liquid chromatography, gas chromatography, and microplate reader were used to determine the glucose concentration, lipid production, and β-carotene concentration, respectively. Data were analyzed using IBM SPSS statistics (v. 24). Results: Cultures with a C/N ratio of 50 produced the greatest amount of lipids during 120 h pi. However, lipid synthesis in the first 48 h pi was very low for all three C/N ratios. Analyses of the lipid composition revealed that oleic acid and linoleic acid were the dominant (60%) fatty acids. Cultures with a C/N ratio of 50 also produced the greatest amount of β-carotene. Conclusion: R. diobovatum in the C/N of 50 culture medium resulted in greater concentrations of lipid and β-carotene. Defining the optimum C/N ratio will enable development of optimized bioprocess engineering parameters

Taxonomical position of pigmented yeast isolated from Antarctic ecosystems

Aim. To determine species composition and taxonomic position of extremotolerant Antarctic yeast. Methods. The objects of research were yeast from Antarctic soils and phytocenosis, which are stored in the Collection of Extremophilic Microorganisms at the Institute of Microbiology and Virology of the National Academy of Sciences of Ukraine, Kiev. Yeast were grown on malt wort (рН 5.0–5.5, temperature 18–20°С). Isolation of genomic DNA was performed using a commercial kit DNA-sorb; amplification of DNA preparations – use of primers NL1 and NL4; phylogenetic analysis – construction of dendrograms showing the position of the studied strains among closely related and typical species. Results. The analysis have shown a high percentage of similarity (98.4–99.9 %) of 18S rRNA genes sequences of yeast Antarctic strains and yeast sequences from the database GenBank. It was found that yeast strains belonged to phylum Basidiomycota (genera Rhodosporidium, Rhodotorula) and Ascomycota (genus Exophiala). Conclusions. As it was shown by phylogenetic analysis, red yeast S33, S48, S182 clustered with Rhodotorula mucilaginosa; S14 – with Rhodosporidium diobovatum and can be attributed to these species. Extremotolerant black yeast S10, S36 and S237 refer to the species Exophiala nigra. Keywords:Antarctica, extremotolerant yeast, phylogenetic analysis, species composition.

Lipid and carotenoid synthesis by Rhodosporidium diobovatum, grown on glucose versus glycerol, and its biodiesel properties

Relationships between lipid and carotenoid synthesis by Rhodosporidium diobovatum were investigated for cell cultures in nitrogen-limited medium (GMY) containing equimolar amounts of carbon of glucose or glycerol. The cultures were also supplemented with additional substrate at 120 h postinoculation (pi) and during a fed-batch experiment. Growth of R. diobovatum on glucose resulted in higher yields of triacyglycerides (TAGs) and carotenoid than when grown on glycerol, even though the cultures contained equimolar amounts of carbon. After the addition of fresh substrate at 120 h pi, total carotenoid concentrations were significantly different from the concentrations measured at 120 h pi in both glucose and glycerol cultures, with no concomitant increase in lipid concentrations, suggesting that carotenoid synthesis is linked to exponential-phase growth, while lipid synthesis is linked to stationary phase. We also compared the calculated properties of biodiesel that could be made with TAGs derived from R. diobovatum with properties of biodiesel made from TAGs of other oleaginous yeasts, microalgae, vegetable oils, and animal fats. This study shows that R. diobovatum can be an effective strain for production of neutral lipids containing high percentages of oleic acid, palmitic acid, and linoleic acid, as well as carotenoids.