Purification and properties of intracellular fructosyl transferase fromAureobasidium pullulans

Intracellular frustosyl transferase was purified fromAureobasidium pullulans C-23 by ethanol fractionation, CM-Sephadex chromatography and preparative disc gel electrophoresis. It was shown to be homogeneous on disc polyacrylamide gel electrophoresis, with a molecular size of 190kDa. The pI value of the enzyme was about 3.7. The enzyme has aK _m value of 0.43 mM for sucrose and was optimally active at pH 5.0 and 60°C. The enzyme was stable from pH 2.5 to 12. It was almost completely inhibited by 5mM Hg²⁺ but was not significantly affected by other cations. The transferase was inactivated by treatment with the tryptophan-specific reagentN-bromosuccinimide and the tyrosine-specific reagent, I₂, suggesting that tryptophan and tyrosine residues are probably located at or near the active site of the enzyme.     

Polysaccharide production by Aureobasidium pullulans: factors affecting polysaccharide formation

Aureobasidium pullulans NRRL 6220 synthesized polysaccharide most actively in media containing sucrose, fructose or maltose with (NH₄)₂SO₄ (0.6 g/l) or ammonium acetate giving greatest yields of the polysaccharide. With (NH₄)₂SO₄ at 1.2 g/l, production of polysaccharide was decreased considerably. Polysaccharide production was highest with an initial pH of 6.5 while biomass formation was better below an initial pH of 5.5. Optimum phosphate concentration for polysaccharide production was 0.03 m.S.M. Badr-Eldin, H.G. El-Masry and O.A. Abd El-Rahman are with the Microbial Chemistry Department, National Research Center, Dokki, Cairo, Egypt; F.H.A. Mohamad is with the Chemical Engineering and Pilot Plant Department, National Research Center, Dokki, Cairo, Egypt. O.M. El-Tayeb is with the Microbiology Department, Faculty of Pharmacy, Cairo University, Egypt.     

Involvement of Branched Units at Position 6 in the Reactivity of a Unique Variety of β-D-Glucan from Aureobasidium pullulans to Antibodies in Human Sera

We recently determined the structure of a unique type of 1,3-β-D-glucan obtained from Aureobasidium pullulans (AP-FBG) and found that it reacted with the antibodies in human sera. The reactivity of AP-FBG to the antibodies was stronger than that of 1,3-β-D-glucan obtained Grifola frondosa (GRN) but weaker than that of 1,3-β-D-glucan from Candida albicans (CSBG). Here, we demonstrated that AP-FBG reacted to IgG antibodies, especially those of the subclasses IgG2, IgG1, and IgG3, in human sera. Moreover, the results of competitive enzyme-linked immunosorbent assays (ELISAs) using various glucan competitors showed that these IgGs recognized branched chains at position 6. This is the first study to report that the branched chains at position 6 of β-D-glucan strongly contribute to its recognition by antibodies in human sera. This high reactivity of AP-FBG to human IgG could be advantageous for the use of this glucan in medicine, e.g., as an immunostimulatory agent.     

Cloning,expression, and characterization of Aureobasidium melanogenum lipase in Pichia pastoris

cDNA of Aureobasidium melanogenum lipase comprises 1254 bp encoding 417 amino acids, whereas genomic DNA of lipase comprises 1311 bp with one intron (57 bp). The lipase gene contains a putative signal peptide encoding 26 amino acids. The A. melanogenum lipase gene was successfully expressed in Pichia pastoris. Recombinant lipase in an inducible expression system showed the highest lipase activity of 3.8 U/mL after six days of 2% v/v methanol induction. The molecular mass of purified recombinant lipase was estimated as 39 kDa using SDS-PAGE. Optimal lipase activity was observed at 35–37 °C and pH 7.0 using p-nitrophenyl laurate as the substrate. Lipase activity was enhanced by Mg²⁺, Mn²⁺, Li⁺, Ca²⁺, Ni²⁺, CHAPS, DTT, and EDTA and inhibited by Hg²⁺, Ag⁺, SDS, Tween 20, and Triton X-100. The addition of 10% v/v acetone, DMSO, p-xylene, and octanol increased lipase activity, whereas that of propanol and butanol strongly inhibited it.     

普鲁兰多糖应用现状研究

介绍了普鲁兰多糖的理化性质和生理功能,阐述了其在农产品、食品、环保、包装、医药、石油等领域的应用现状,并对其良好的市场前景进行了展望。     

Pullulan production from brewery wastes by Aureobasidium pullulans

The production of pullulan from brewery wastes by Aureobasidium pullulans in shake flask culture was investigated. The maximum pullulan concentration (6.0g/l) was obtained after 72h of fermentation. The external addition of nutrients into the spent grain liquor improved significantly the production of pullulan. In this case, the highest values of pullulan concentration (11.0±0.5g/l), pullulan yield (48.2±1.5%), and sugar utilization (99.0±0.5%) were obtained in the medium (pH 6.5–7.5) supplemented with K₂HPO₄ 0.5%, l-glutamic acid 1%, olive oil 2.5%, and Tween 800.5%.     

New exopolysaccharides produced by Aureobasidium pullulans grown on glucosamine

The polysaccharides produced by Aureobasidium pullulans, grown using glucosamine as the carbon source, were investigated by means of methylation analysis, affinity chromatography and NMR spectroscopy. The results indicated that, besides a small amount of pullulan, this micro-organism was capable of producing-in low yields-mixtures of at least two different complex polysaccharides containing mainly mannose and galactose. (1)H NMR spectra of two fractions obtained by lectin affinity chromatography indicated that one polymer was constituted exclusively of mannose residues while the other contained both galactofuranosyl and mannopyranosyl residues.     

Fungus propagules in plastids: the mycosome hypothesis

A stress-induced "mycosome" phase of Aureobasidium pullulans consisting of minute reproductive propagules that may revert directly to walled yeast cells is described. Mycosomes detected by light- and electron-microscopy reproduce within senescent plant plastids, and display three developmental pathways: wall-less cells (protoplasts), yeast cells, or membrane-bounded spherules that harbor plastids. Widespread in plant and algal cells, mycosomes are produced by both ascomycete and basidiomycete fungi. Electronic Publication     

The influence of moisture on the suppression of Pseudomonas syringae by Aureobasidium pullulans on an artificial leaf surface

Abstract Isolates of Aureobasidium pullulans which produce antibacterial metabolites were compared with non-antibiotic-producing isolates of Tremella foliacea and Trichosporon beigelii for their ability to inhibit growth of Pseudomonas syringae pv phaseolicola . The bacteria and fungi were co-inoculated on an artificial leaf surface under conditions of low and high water availability. Under conditions of excess moisture, antibiotic production gave no advantage to the Aureobasidium isolates, and all the yeasts were equally antagonistic. Under drier conditions the Aureobasidium isolates reduced the population of P. syringae by 96–99%, a result which was significantly different from that which occurred when the bacteria were co-inoculated with the other yeasts under these conditions. An antibacterial compound, similar to that produced in liquid culture by Aureobasidium , was detected in washings from the artificial leaf surface following growth of this species.