مقاله ۲۰۰۳: پین زایی استرین های قارچ دکمه ای روی خاک پوششی دارا و فاقد میکروارگانیم های زنده

Primordia initiation of mushroom (Agaricus bisporus) strains on axenic casing materials.

Abstract

The mushroom (Agaricus bisporus) has a requirement for a "casing layer" that has specific physical, chemical and microbiological properties which stimulate and promote the initiation of primordia. Some of these primordia then may develop further into sporophores, involving differentiation of tissue. Wild and commercial strains of A. bisporus were cultured in axenic and nonaxenic microcosms, using a rye grain substrate covered by a range of organic and inorganic casing materials. In axenic culture, A. bisporus (commercial strain A15) was capable of producing primordia and mature sporophores on charcoal (wood and activated), anthracite coal, lignite and zeolite, but not on bark, coir, peat, rockwool, silica or vermiculite. Of six strains tested, only the developmental variant mutant, B430, produced rudimentary primordia on axenic peat-based casing material. However, none of these rudimentary primordia developed differentiated tissues or beyond 4 mm diameter, either on axenic casing material in the microcosms or in larger-scale culture. In larger-scale, nonaxenic culture, strain B430 produced severely malformed but mature sporophores in similar numbers to those of other strains. Typically, 3-6% of primordia developed into mature sporophores, but significant differences in this proportion, as well as in the numbers of primordia produced, were recorded between 12 A. bisporus strains.

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مقاله ۲۰۱۳: خالص سازی و توصیف خصوصیات پلی فنول اکسیدز از قارچ دکمه ای

Purification and Characterization of Polyphenol Oxidase from Agaricus Bisporus

ABSTRACT

A polyphenol oxidase (PPO) was isolated from Agaricus bisporus using ammonium sulfate precipitation, combined with DEAE–Sepharose Fast Flow chromatography and Phenyl Sepharose CL-4B chromatography. The molecular weight of the purified PPO was determined to be about 43 kDa with N-terminal sequence Ala-Thr-Asn-Ser-Gly-Thr-Leu-Ile-Ile-Phe by Edman degradation. The optimum temperature and pH for the PPO activity was 20 °C and pH 6.5-7.0. Moreover, it was stable at 30 °C and 40 °C over a 60 min pre-incubation time period. The K_m and V_max values of this PPO for catechol were 0.67 mM and 3333 U/ml min⁻¹, respectively. In addition, following the cross linking with PPO, the emulsifying activity index, foam capacity and foam stability of the whey proteins were evaluated to be modified. This work was useful to better understand PPO from A. bisporus, and may lead to its practical use in the future.

 نقش سی ترمینال لاکیز اری فور قارچ شاه صدف پلوروتوس ارینجی در تعیین ساختار آنزیم، خصوصیات کاتالیتیک و پایداری آن

Role of the C-terminus of Pleurotus eryngii Ery4 laccase in determining enzyme structure, catalytic properties and stability

The ERY4 laccase gene of Pleurotus eryngii is not biologically active when expressed in yeast. To explain this finding, we analysed the role of the C-terminus of Ery4 protein by producing a number of its different mutant variants. Two different categories of ERY4 mutant genes were produced and expressed in yeast: (i) mutants carrying C-terminal deletions and (ii) mutants carrying different site-specific mutations at their C-terminus. Investigation of the catalytic properties of the recombinant enzymes indicated that each novel variant acquired different affinities and catalytic activity for various substrates. Our results highlight that C-terminal processing is fundamental for Ery4 laccase enzymatic activities allowing substrate accessibility to the enzyme catalytic core. Apparently, the last 18 amino acids in the C-terminal end of the Ery4 laccase play a critical role in enzyme activity, stability and kinetic and, in particular biochemical and structural data indicate that the K532 residue is fundamental for enzyme activation. These studies shed light on the structure/function relationships of fungal laccases and will enhance the development of biotechnological strategies for the industrial exploitation of these enzymes.

پنجم اسفند ۱۳۹۱

مقاله ۲۰۱۲: افزایش عملکرد و انبار داری قارچ دکمه ای از طریق محلول پاشی قبل از برداشت با اسید آسکوربیک و کلرید کلسیم