Microbial community utilization of recalcitrant and simple carbon compounds: impact of oak-woodland plant communities

Abstract

Little is known about how the structure of microbial communities impacts carbon cycling or how soil microbial community composition mediates plant effects on C-decomposition processes. We examined the degradation of four (13)C-labeled compounds (starch, xylose, vanillin, and pine litter), quantified rates of associated enzyme activities, and identified microbial groups utilizing the (13)C-labeled substrates in soils under oaks and in adjacent open grasslands. By quantifying increases in non-(13)C-labeled carbon in microbial biomarkers, we were also able to identify functional groups responsible for the metabolism of indigenous soil organic matter. Although microbial community composition differed between oak and grassland soils, the microbial groups responsible for starch, xylose, and vanillin degradation, as defined by (13)C-PLFA, did not differ significantly between oak and grassland soils. Microbial groups responsible for pine litter and SOM-C degradation did differ between the two soils. Enhanced degradation of SOM resulting from substrate addition (priming) was greater in grassland soils, particularly in response to pine litter addition; under these conditions, fungal and Gram+ biomarkers showed more incorporation of SOM-C than did Gram- biomarkers. In contrast, the oak soil microbial community primarily incorporated C from the added substrates. More (13)C (from both simple and recalcitrant sources) was incorporated into the Gram- biomarkers than Gram+ biomarkers despite the fact that the Gram+ group generally comprised a greater portion of the bacterial biomass than did markers for the Gram- group. These experiments begin to identify components of the soil microbial community responsible for decomposition of different types of C-substrates. The results demonstrate that the presence of distinctly different plant communities did not alter the microbial community profile responsible for decomposition of relatively labile C-substrates but did alter the profiles of microbial communities responsible for decomposition of the more recalcitrant substrates, pine litter and indigenous soil organic matter.

Microbial community structure mediates response of soil C decomposition to litter addition and warming

“…6) reflecting previous knowledge regarding C substrate preferences, with fungi dominating litter decomposition and bacteria dominating soil decomposition (Strickland and Rousk, 2010;Gude et al, 2012). The higher soil-C assimilation of gram-positive bacteria relative to gram-negative bacteria is also consistent with previously published research confirming greater decomposition of soil-C by grampositive bacteria (Waldrop and Firestone, 2004;Gleixner, 2006, 2008;Bird et al, 2011). In this experiment temperature and litter addition most strongly impacted CO 2 production and microbial community structure (Figs.…”

Storage and stability of organic matter and fossil carbon in a Luvisol and Phaeozem with continuous maize cropping: A synthesis

“…Distinct microbial C sources used for the synthesis of PLFAs that are characteristic for Gram-positive and Gram-negative bacteria could not be identified. However, some mono-unsaturated PLFAs, that are characteristic for Gram-negative bacteria (Zelles, 1999), appeared to indicate a preferred substrate usage of plant material, whereas saturated PLFAs (iso, anteiso, and branched chain), typical components of Grampositives (Haack et al, 1994), seem to suggest a preference of these bacteria for SOM C. This would be in line with results from Waldrop and Firestone (2004), but further research is needed on that topic.…”

Contrasting effects of ammonium and nitrate inputs on soil CO2 emission in a subtropical coniferous plantation of southern China

“…PLFAs in soils indicate microbial biomass and fingerprint microbial community composition (Frostegard and Bååth 1996). Although the PLFA method relying on extraction and analysis of specific cell components cannot provide information about the physiological status or diversity of the microbial community (Roslev et al 1998), it is widely applied to investigate the effects of experimental N deposition in various forest and grassland ecosystems (Waldrop and Firestone 2004;van Diepen et al 2010). Briefly, 8 g of lyophilized soil was extracted using a single-phase chloroform-methanol-citrate buffer (1:2:0.8) system with the amount of citrate buffer corrected to account for existing soil water content (Ferre et al 2012;Zhang et al 2013a).…”