Pectinolytic ability of some mycorrhizal and saprophytic hymenomycetes.

Ectomycorrhizal fungi of the genus Boletus were able to use a restricted number of hexoses and disaccharides as single carbon sources. In the presence of a small amount of "start" glucose, induced growth occurred on a few additional carbohydrates. Even in the presence of "start" glucose, the ectomycorrhizal fungi could not utilize pectin, whereas certain litter-decomposing fungi grew rapidly using this compound as a carbon source. Only the litter-decomposers were able to use galacturonic acid, the monomer of pectic acid, as a carbon source. Possible mechanisms for the penetration and growth of ectomycorrhizal fungi into the middle lamellae of the root parenchyma are discussed.