The effect of resource quantity and resource stoichiometry on microbial carbon-use-efficiency

Abstract

The carbon-use-efficiency (CUE) of microorganisms is an important parameter in determining ecosystem-level carbon (C) cycling; however, little is known about how variance in resources affects microbial CUE. To elucidate how resource quantity and resource stoichiometry affect microbial CUE, we cultured four microorganisms - two fungi (Aspergillus nidulans and Trichoderma harzianum) and two bacteria (Pectobacterium carotovorum and Verrucomicrobium spinosum) - under 12 unique C, nitrogen (N) and phosphorus (P) ratios. Whereas the CUE of A. nidulans was strongly affected by C, bacterial CUE was more strongly affected by mineral nutrients (N and P). Specifically, CUE in P. carotovorum was positively correlated with P, while CUE of V. spinosum primarily depended on N. This resulted in a positive relationship between fungal CUE and resource C : nutrient stoichiometry and a negative relationship between bacterial CUE and resource C : nutrient stoichiometry. The difference in the direction of the relationship between CUE and C : nutrient for fungi vs. bacteria was consistent with differences in biomass stoichiometry and suggested that fungi have a higher C demand than bacteria. These results suggest that the links between biomass stoichiometry, resource demand and CUE may provide a mechanism for commonly observed temporal and spatial patterns in microbial community structure and function in natural habitats.

C:N:P stoichiometry and nutrient limitation of the soil microbial biomass in a grazed grassland site under experimental P limitation or excess

“…It is likely that the species composition of the microbial biomass would differ in 0_0 from the other treatments due to the change in CNP stoichiometry. Since fungal biomass contains relatively more C than bacterial biomass, it is suggested that fungi might have a higher C-demand than bacteria, while bacteria are more constrained by nutrient ratios (Keiblinger et al 2010). We found only a weak correlation between the CFE and SIR measurements of C mic , and variation was particularly large in the high P-fertiliser treatments (15_15, 30_0, 30_30).…”

Soil labile organic carbon and carbon-cycle enzyme activities under different thinning intensities in Chinese fir plantations

“…For example, Bolat (2014) and found thinning increased labile organic carbon, but decreases have been reported in other studies (Schilling et al, 1999;Hassett and Zak, 2005). In addition, because seasonal variations in soil temperature and aboveground vegetation might affect the ability or strategy of microbial decomposers to efficiently use SOC, the thinning effect on labile SOC and enzymatic activities may vary seasonally (Balser and Wixon, 2009;Liptzin and Silver, 2009;Keiblinger et al, 2010;Zhou et al, 2012).…”

Effect of warming and drought on grassland microbial communities

“…Plant biomass data at the site also suggest that because of the lack of moisture, NPP (net primary production) was decreased relative to controls . The potential reduction in labile carbon and nitrogen entering the rhizosphere could also be a partial cause for the decline of microbial phyla such as Verrucomicrobia who are known to be heterotrophs (Hedlund et al, 1997) and are sensitive to nitrogen ratios (Keiblinger et al, 2010). An analysis of the effect of warming on community structure showed no significant difference despite the effect on abundance.…”