Studies of fungi in pasture soils

Abstract

Fungi isolated from the surfaces of live roots or root debris were compared for their ability to use a range of compounds as carbon and energy sources. Most of the fungi had similar abilitie" but one isolate of Mortierella alpina was exceptional in not growing on xylose, sucrose, or pectin, and growing poorly on glucose. An isolate of Cladosporium sp. grew better on glucose than any of the others, and was the only one that grew poorly on starch. Paecilomyces carneus, a dominant isolate from debris, and several strains of Mortierella decomposed chitin readily; Gliocladium roseum did so less readily; and Trichoderma sporulosum and Humicola sp. only weakly. The four isolates of Fusarium oxysporum that were tested all attacked cellulose, but not equally readily. They differed more in their ability to produce celIulase than in their ability to grow on cellulose or disintegrate cellulose fibres. The four isolates of Fusarium oxysporum and one of Cylindrocarpon radicicola tolerated 4.6% of myrobalan tannin better than did other fungi. Several fungi used tannins as a carbon source.