The chemistry of mould tissue

Abstract

THE cells walls of fungi lack the structure exhibited by those of higher plants, and at the same time are markedlyinert towards the action of most reagents and stains. Many histological investigators, towards the close of the last century, occupied themselves with speculating on the nature ofthe cell-wall constituents. Tests for the usual structural constituents of plants were indefinite. Most of the workers assumed cellulose to be present, though so altered by combination or infiltration with other materials as to be difficult of characterisation. Several names were given to the cell-wall substance, the most general being "fungus cellulose." A chemical examination of this substance was made by Winterstein [1894; 1895] who showed it to be chitinous in nature. His investigations were mainly on material from higher fungi and his analysis showed about 3-6 to 3-9 % nitrogen in his preparations. From Boletus edulis Sch6ll [1908] obtained, by exhaustive extractions with hot 10 % KOH solution, a material which he described as pure chitin, yielding on hydrolysis 78 % of crystalline hexosamine hydrochloride. He concluded that the cell-walls of this organism are either composed of pure chitin or of chitin in very loose combination with a nitrogen-free carbohydrate. Later Sumi [1929] obtained chitin from the walls of spores of Aspergillus oryzae. He considered it to be present there in association with other substances. Proskuriakow [1926] has prepared from Boletus, Agaricus and Polyporus, by repeated extraction with 10 % NaOH followed by treatment with a solution of potassium permanganate, prepara- tions of high nitrogen content (6.1-6-3 %). The actual amount of such material in the fungi is apparently small, since the yield from Agaricus was 5 % and from Polyporus 3-5 %. Takata [1929] by similar means obtained from Aspergillus oryzae 3-18 % of "chitin" containing 6-37 % N.