Aimin Ma

Identification and antioxidant activity of melanin isolated from Hypoxylon archeri, a companion fungus of Tremella fuciformis

Melanin produced by Hypoxylon archeri, a companion fungus of Tremella fuciformis, was purified from the submerged culture medium and designated as HM. Ultraviolet‐visible and FTIR spectra of the purified HM showed significant similarities with those of the synthesized melanin derived from tyrosine. Thus, the HM melanin was identified to be derived from the precursor molecule of tyrosine or dihydroxyphenylalanine (DOPA).

Comparing the sugar profiles and primary structures of alkali-extracted water-soluble polysaccharides in cell wall between the yeast and mycelial phases from Tremella fuciformis

To gain insights into dimorphism, cell wall polysaccharides from Tremella fuciformis strains were obtained from alkali-extracted water-soluble fractions PTF-M38 (from the mycelial form), PTF-Y3 and PTF-Y8 (from the yeast form) of T. fuciformis strains were used to gain some insights into dimorphism study. Their chemical properties and structural features were investigated using gel permeation chromatography, gas chromatography, UV and IR spectrophotometry and Congo red binding reactions. The results indicated that the backbones of PTF-M38, PTF-Y3 and PTF-Y8 were configured with α-linkages with average molecular weights of 1.24, 1.08, and 1.19 kDa, respectively. PTF-M38 was mainly composed of xylose, mannose, glucose, and galactose in a ratio of 1:1.47:0.48:0.34, while PTF-Y3 and PTF-Y8 were mainly composed of xylose, mannose and glucose in a ratio of 1:1.65:4.06 and 1:1.21:0.44, respectively. The sugar profiles of PTF-M38, PTF-Y3 and PTF-Y8 were also established for further comparison. These profiles showed that all three polysaccharides contained the same sugars but in different ratios, and the carbon sources (xylose, mannose, glucose, and galactose) affected the sugar ratios within the polysaccharides.

Effects of Environmental Factors on Dimorphic Transition of the Jelly Mushroom Tremella Fuciformis

Abstract. Tremella fuciformis, a typical dimorphic fungus, displays two distinct morphological transitions: (i) yeast-pseudohyphae transition; (ii) yeast-hyphae transition. To understand the mechanism of its dimorphism, we initiated a study by investigating how environmental factors affect the yeast-to-pseudohypha transition, including pH value, temperature, carbon source, nitrogen source, cultural time, ethanol and inoculum size. Our studies showed that the optimal conditions for yeast-to-pseudohypha transition were as follows: incubating at 25 to 30°C for 3 to 7 days in media containing glucose as the carbon source, ammonium as the nitrogen source and 10 ml/L ethanol. Below a threshold of inoculum size (105 cells/L), the transition ratio fluctuated markedly, which made us propose that quorum sensing molecules contribute to the dimorphic behavior in T. fuciformis.

Characterization of the highly active fragment of glyceraldehyde-3-phosphate dehydrogenase gene promoter for recombinant protein expression in Pleurotus ostreatus

Developing efficient native promoters is important for improving recombinant protein expression by fungal genetic engineering. The promoter region of glyceraldehyde-3-phosphate dehydrogenase gene in Pleurotus ostreatus (Pogpd) was isolated and optimized by upstream truncation. The activities of these promoters with different lengths were further confirmed by fluorescence, quantitative real-time PCR and Western blot analysis. A truncated Pogpd-P2 fragment (795 bp) drove enhanced green fluorescence protein (egfp) gene expression in P. ostreatus much more efficiently than full-length Pogpd-P1. Further truncating Pogpd-P2 to 603, 403 and 231 bp reduced the eGFP expression significantly. However, the 403-bp fragment between -356 bp and the start codon was the minimal but sufficient promoter element for eGFP expression. Compact native promoters for genetic engineering of P. ostreatus were successfully developed and validated in this study. This will broaden the preexisting repertoire of fungal promoters for biotechnology application.

An Improved Total RNA Extraction Method for White Jelly Mushroom Tremella fuciformis Rich in Polysaccharides

Abstract An improved method for extracting high quality and quantity RNA from a jelly mushroom and a dimorphic fungus—Tremella fuciformis which is especially rich in polysaccharides, is described. RNA was extracted from T. fuciformis mycelium M1332 and its parental monokaryotic yeast-like cells Y13 and Y32. The A260/280 and A260/230 ratios were both approximately 2, and the RNA integrity number was larger than 8.9. The yields of RNA were between 108 and 213 μg/g fresh wt. Downstream molecular applications including reverse transcriptional PCR and quantitative real-time PCR were also performed. This protocol is reliable and may be widely applicable for total RNA extraction from other jelly mushrooms or filamentous fungi rich in polysaccharides.