Details

Autor(en) / Beteiligte

• German, Donovan P
• Chacon, Stephany S
• Allison, Steven D
• Frey, SD

Titel

Substrate concentration and enzyme allocation can affect rates of microbial decomposition

Ist Teil von

• Ecology (Durham), 2011-07, Vol.92 (7), p.1471-1480

Ort / Verlag

Washington, DC: Ecological Society of America

Erscheinungsjahr

2011

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• A large proportion of the world's carbon is stored as soil organic matter (SOM). However, the mechanisms regulating the stability of this SOM remain unclear. Recent work suggests that SOM may be stabilized by mechanisms other than chemical recalcitrance. Here, we show that the mineralization rate of starch, a plant polymer commonly found in litter and soil, is concentration dependent, such that its decomposition rate can be reduced by as much as 50%% when composing less than ∼∼10%% of SOM. This pattern is largely driven by low activities of starch-degrading enzymes and low inducibility of enzyme production by microbial decomposers. The same pattern was not observed for cellulose and hemicellulose degradation, possibly because the enzymes targeting these substrates are expressed at constitutively high levels. Nevertheless, given the heterogeneous distribution of SOM constituents, our results suggest a novel low-concentration constraint on SOM decomposition that is independent of chemical recalcitrance. These results may help explain the stability of at least some SOM constituents, especially those that naturally exist in relatively low concentrations in the soil environment.