The cell walls of Agaricus bisporus and Agaricus campestris fruiting body hyphae

Abstract

The hyphal walls of Agaricus bisporus and Agaricus campestris fruiting bodies were isolated and purified. Quantitative analyses revealed that these walls consisted mainly of carbohydrates (78.3-79.2%), lipids (9.9-10.1%), and proteins (8.7-10.2%). The major components of carbohydrate polymers were glucose, N-acetylglucosamine, and glucosamine. In addition, small quantities of galactose and mannose have been found. N-Acetylglucosamine and glucosamine were identified chemically and enzymatically, and also by infrared spectrum and X-ray diffraction analyses, as chitin and chitosan. Neutral polysaccharides include an alkali-soluble glucan with alpha (1-3) linkages and a beta (1-3)- and beta (1-6)-linked glucan. The lipid fractions in both hyphal walls contained precursors of melanin, this pigment being largely represented in Agaricus spore walls. Amino acids analyses indicate that structural wall proteins were very similar in both organisms. In electron micrographs of ultrathin sections of hyphae no distinct layering was apparent in contrast with spore walls of the same organism, which show two wide well-defined layers.

Relationship between the presence of wall mucilage and the cellular disruption method employed in Agaricus bisporus tertiary mycelium

“…The overall composition of hyphal cell walls of A. bisporus fruiting bodies has been reported before [10]. These walls were composed mainly of carbohydrate (more than 75%), protein and lipid making up the remainder in similar proportion.…”

“…Total neutral sugar content of whole walls, water-soluble polysaccharide and mucilage-free walls were determined by the anthrone method [3] using glucose as standard. The aminosugar content was estimated by the method of Chen and Johnson [2] on hydrolysates (6 N HC1 at 105°C for 6 h) after removal of the neutral sugars and amino acids according to Novaes-Ledieu and Garcia Mendoza [9]. Total protein was determined by the method of Lowry et al [7] on hot alkaline extracts (1 N NaOH, 2 h at 100°C) of walls and on water solubilized polysaccharide.…”

“…The hyphal suspensions (approx. 0.5 g fresh wt./ml) were submitted in the cold (4°C) to the action of one of the following: When the hyphal suspensions were completely disrupted, determined by phase-contrast microscopic examination, the walls were purified as previously described [10].…”

Chemical Analysis of the Lamella Walls of Agaricus bisporus Fruit Bodies

“…tuted the most abundant material, followed by amino sugars and proteins. An important amount of phenols (about 6%) associated with the lipid material [18] was found in these walls, as well as a significant quantity of ash. Carbohydrate analysis of the isolated walls and fractions showed that glucose was the main neutral sugar (about 85%) although lesser amounts of galactose, mannose, and xylose were also found ( Table 2).…”

Colloidal gold-complexed chitosanase: a new probe for ultrastructural localization of chitosan in fungi

“…Chitosan has been reported to occur in the cell walls of Phycomyces, Mucor, Zygorhynchus and Choanephora (Bartnicki-Garcia, 1968;Letourneau et al, 1976;Datema et al, 1977b). It also occurs in the spore and hyphal walls of Agaricus (Novaes-Ledieu & Garcia Mendoza, 1981), in spores of rust (Hadwiger & Line, 1981) and Saccharomyces (Briza et al, 1988), and in Fusarium hyphae and spores . In some Zygomycetes, it has been demonstrated that chitosan derives from N-deacetylation of nascent chitin by chitin deacetylase (Araki & Ito, 1988;Trudel & Asselin, 1990).…”