Abstract
Trace gas uptake by microorganisms controls the oxidative capacity of the troposphere, but little is known about how this important function is affected by changes in soil microbial diversity. This article bridges that knowledge gap by examining the response of the microbial community-level physiological profiles (CLPPs), carbon dioxide (CO2) production, and molecular hydrogen (H2) and carbon monoxide (CO) oxidation activities to manipulation of microbial diversity in soil microcosms. Microbial diversity was manipulated by mixing nonsterile and sterile soil with and without the addition of antibiotics. Nonsterile soil without antibiotics was used as a reference. Species composition changed significantly in soil microcosms as a result of dilution and antibiotic treatments, but there was no difference in species richness, according to PCR amplicon sequencing of the bacterial 16S rRNA gene. The CLPP was 15% higher in all dilution and antibiotic treatments than in reference microcosms, but the dilution treatment had no effect on CO2 production. Soil microcosms with dilution treatments had 58%-98% less H2 oxidation and 54%-99% lower CO oxidation, relative to reference microcosms, but did not differ among the antibiotic treatments. These results indicate that H2 and CO oxidation activities respond to compositional changes of microbial community in soil.
Highlights
Soil is a heterogeneous environment where aboveground biomass, void surrounding aggregates, and uneven water availability shape various nutrient, physical, and chemical gradients (Lehmann et al 2008; Vos et al 2013; Young and Crawford 2004)
The relative H2 and carbon monoxide (CO) oxidation activities of each dilution and antibiotic treatment were significantly lower than the 100% activity displayed by the reference microcosms (Figure 1A-B)
These results showed that the soil dilution and antibiotic treatments affected the generalist processes involved in CO2 production and community level physiological profiles (CLPPs) differently than the specialist functions responsible for trace gas oxidation in soil
Summary
Soil is a heterogeneous environment where aboveground biomass, void surrounding aggregates, and uneven water availability shape various nutrient, physical, and chemical gradients (Lehmann et al 2008; Vos et al 2013; Young and Crawford 2004). Direct manipulation of microbial diversity is a way to determine how a particular function is responding to changes in diversity This can be done by assembling an artificial microbial population, or by reducing the inherent diversity with fumigation or dilution to extinction methods. Application of these methods has shown that the productivity of the function is differently impacted depending on whether specialized functions, such as recalcitrant carbon degradation (Maron et al 2018) and denitrification (Philippot et al 2013), or a broad function, such as carbon dioxide (CO2) production (Langenheder et al 2006) and labile carbon degradation (Baumann et al 2013), is examined
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