DECOMPOSITION OF WHEAT STRAW AND RELATED-COMPOUNDS BY FUNGI ISOLATED FROM STRAW IN ARABLE SOILS

Eight fungi, isolated from straw decomposing in soil were tested for their ability to degrade lignin, cellulose, phenolic acids and intact straw lengths. Fusarium culmorum. Trichoderma viride and Chaetomium globosum could each degrade cellulose but not lignin. Five basidiomycete isolates (a Typhula sp. and four unidentified isolates R38. W54. N45 and N46) degraded both substrates. All of the fungi decomposed p-coumaric and ferulic acid except for T. viride and Typhula sp. which showed little or no activity against ferulic acid. F. culmorum and T. viride decomposed only ca 20% of the intact straw lengths. The other six fungi all caused more straw decay. Weight losses from straw in excess of 20% appear to depend on the presence of lignin-modifying or -degrading organisms. Whilst C. glubosum does not degrade lignin it has been shown to demethoxylate lignin and thus gain access to "protected" polysaccharides. Typhula sp. R38, W54, N46 and N45. all lignin-degrading basidiomycetes. were compared with 11 other basidiomycete isolates for their ability to decay intact straw: weight losses ranged from 21-45% after 84 days. The significance of such organisms to straw decay in soil has not been recognized previously. © 1990.