Aspen Bibliography

Decomposition of heterogeneous substrates; an experimental investigation of a hypothesis on substrate and microbial properties

Document Type

Article

Journal/Book Title/Conference

Soil biology and biochemistry

Volume

22

Issue

2

First Page

161

Last Page

167

Publication Date

1990

Abstract

The production-to-assimilation ratio (microbial efficiency) of a microorganism feeding on a substrate depends both on the organism and the substrate. An experiment was set up to investigate whether the microbial efficiency can be defined as the product of a microbial property (an efficiency factor) and a substrate property (substrate quality). By following changes in carbon and organic nitrogen content of birch, aspen and spruce wood, which were degraded by either the brown-rot fungus Poria oleracea or the white-rot fungus Phanernchaete chrysosporium over a 130 day period, we showed that this seems to be the case. It was also found that the substrate quality decreased in the order birch > aspen > spruce. which corresponded to increasing lignin concentrations. However, aspen and spruce appeared much closer in quality than birch and aspen although the latter two are much closer in lignin concentrations. For any given substrate P. oleracea had a microbial elliciency which was ca 50% higher than that of Ph. rhrysosporium. In addition, the experiment showed that when both nitrate and ammonium were available as N sources Ph. chrysosporium preferentially used nitrate whereas P. oleracea started using nitrate only when all ammonium in the growth medium had been exhausted.

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