Light calcium carbonate improves pullulan biosynthesis by Aureobasidium pullulans under high concentration of sugar.

The effects of light calcium carbonate (CaCO3) on pullulan biosynthesis by Aureobasidium pullulans NCPS2016 were investigated. Light CaCO3 enhanced pullulan production by 12.4 % when added to the low concentration of fructose broth compared with K2HPO4. Pullulan production was further improved when increasing both the concentrations of light CaCO3 and fructose. Compared to K2HPO4, light CaCO3 improved the activities of UDP-glucose pyrophosphorylase, α-phosphoglucose mutase, UDP-glucosyltransferase, and glucosyltransferase relevant to pullulan biosynthesis, and the gene transcriptional levels of UDP-glucose pyrophosphorylase, α-phosphoglucose mutase, UDP-glucosyltransferase, and glucose kinase were enhanced. During 30-liter fermentation, 144.3 g/L of purified pullulan was produced from 200 g/L of fructose and 15 g/L of light CaCO3 within 168 h, with the yield and productivity of 0.72 g/g and 0.86 g/L/h respectively. This is the first report that light CaCO3 improves pullulan production significantly.

High pullulan biosynthesis from high concentration of glucose by a hyperosmotic resistant, yeast-like fungal strain isolated from a natural comb-honey.

A novel, yeast-like fungal strain, Aureobasidium melanogenum TN3-1, that was isolated from natural honey can actively transform 140.0 g/L of glucose into 110.29 ±â€¯2.17 g/L of pullulan during fermentation, whereas A. melanogenum P16 and TN1-2 converted 140.0 g/L of glucose into only 45.81 ±â€¯1.7 g/L and 48.7 ±â€¯2.6 g/L of pullulan, respectively. It was noted that most of the cells in the culture of the strain TN3-1 were arthroconidia, while all of the yeast-like fungal cells of A. melanogenum P16 cultivated under the same conditions were blastoconidia. The cell sizes, cell walls and the number of small vacuoles of A. melanogenum TN3-1 were also much larger, thicker and higher, respectively, than those of A. melanogenum P16. The glycerol, trehalose and glycogen content in the A. melanogenum TN3-1 cells was higher than that of the A. melanogenum P16 and TN1-2 cells.

Diversity of xerotolerant and xerophilic fungi in honey.

Fungi can colonize most of the substrata on Earth. Honey, a sugary food produced by bees (and other insects) has been studied little in terms of its fungal diversity. We have surveyed and evaluated the presence of xerotolerant and xerophilic fungi in a set of honey bee samples collected from across Spain. From 84 samples, a total of 104 fungal strains were isolated, and morphologically and phylogenetically characterized. We identified 32 species distributed across 16 genera, most of them belonging to the ascomycetous genera Aspergillus, Bettsia, Candida, Eremascus, Monascus, Oidiodendron, Penicillium, Skoua, Talaromyces and Zygosaccharomyces. As a result of this survey, eight new taxa are proposed: i.e. the new family Helicoarthrosporaceae, two new genera, Helicoarthrosporum and Strongyloarthrosporum in Onygenales; three new species of Eurotiales, Talaromyces affinitatimellis, T. basipetosporus, and T. brunneosporus; and two new species of Myxotrichaceae, Oidiodendron mellicola, and Skoua asexualis.