'Lazy' microbes lead buildup of organic material

A study from the University of Vienna and the International Institute of Applied System Analysis (IIASA) published in the journal Nature Communications explores the idea that "lazy" microbes -- those that rely on other microbes for digestive enzymes to digest plant material -- are responsible for the build-up of organic material in soil.

They achieve this by regulating the rate of decomposition and increasing the amount of microbial remains in the soil. The carbon and nitrogen stores in the soil are from leftover carbon dioxide and soluble inorganic nitrogen that did not decompose.

"It's a strategy we see all over nature," IIASA Evolution and Ecology Program Director Ulf Dieckmann said. "Cheaters are everywhere -- across many contexts. It's an evolutionarily successful strategy to save resources and thus become more competitive."

The study shows the presence of lazy microbes slows the decomposition of organic material, which then accumulates in the soil.

"This happens because the presence of microbial cheaters ultimately reduces the total amount of enzymes produced by the microbial community, while the total amount of microbial biomass stays about the same" Christina Kaiser, University of Vienna ecologist and IIASA guest researcher, said.

A model developed during Kaiser’s postdoctoral fellowship at IIASA helped in the study.

"The unique thing about this model is that it simulates the life and death of individual microorganisms in a tiny space, and can encompass the positive and negative influences between neighboring microbes," Kaiser said. "In contrast to a traditional soil decomposition model, our model can elucidate mechanisms that depend on social dynamics that emerge on the microbial community level, but are driven by individual interactions among microbes competing for food and space at the smallest scale."

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International Institute for Applied Systems Analysis Schloßpl. 1 Laxenburg, Niederösterreich - 2361

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