Biogeochemistry

, Volume 117, Issue 2–3, pp 473–490

Using microbial communities and extracellular enzymes to link soil organic matter characteristics to greenhouse gas production in a tidal freshwater wetland

  • Ember M. Morrissey
  • David J. Berrier
  • Scott C. Neubauer
  • Rima B. Franklin
Article

DOI: 10.1007/s10533-013-9894-5

Cite this article as:
Morrissey, E.M., Berrier, D.J., Neubauer, S.C. et al. Biogeochemistry (2014) 117: 473. doi:10.1007/s10533-013-9894-5

Abstract

To gain a more mechanistic understanding of how soil organic matter (OM) characteristics can affect carbon mineralization in tidal freshwater wetlands, we conducted a long-term in situ field manipulation of OM type and monitored associated changes in carbon dioxide (CO2) and methane (CH4) production. In addition, we characterized microbial community structure and quantified the activity of several extracellular enzymes (EEA) involved in the acquisition of carbon, nitrogen, and phosphorus. Treatments included a plant litter addition, prepared using naturally-senescing vegetation from the site, and a compost amendment, designed to increase the concentration of aged, partially humified, OM. Both types of OM-amended soils had CO2 production rates 40–50 % higher than unamended control soils, suggesting that the added OM had inherently higher quality and/or availability than the native soil OM. Rates of CO2 production were not correlated with microbial community structure or EEA except a modest relationship with cellulose breakdown via the Km of β-1,4-glucosidase. We interpret this lack of correlation to be a consequence of high functional redundancy of microorganisms that are capable of producing CO2. Rates of CH4 production were also influenced by OM quality, increasing by an order of magnitude with plant litter additions relative to compost-amended and control soils. Unlike CO2, rates of CH4 production were significantly correlated with the microbial community structure and with enzyme kinetic parameters (Vmax and Km) for both carbon (β-1,4-glucosidase, 1,4-β-cellobiosidase, and β-d-xylosidase) and nitrogen acquisition (leucyl aminopeptidase). The monophyletic nature of methanogenic archaea, combined with their reliance on a small select group of organic substrates produced via enzyme-mediated hydrolysis and subsequent bacterial fermentation, provides a basis for the strong links between microbial community structure, EEA, and CH4 production. Our results suggest that incorporating microbial community structure and EEA into conceptual models of wetland OM decomposition may enhance our mechanistic understanding of, and predictive capacity for, biogeochemical process rates.

Keywords

Microbial ecology Decomposition Anaerobic Methanogenesis Wetland restoration 

Supplementary material

10533_2013_9894_MOESM1_ESM.pdf (204 kb)
Representative enzyme saturation curves fit with the Michaelis–Menten equation (Reaction rate = Vmax*[S]/(Km + [S]) to calculate Km (μM substrate) and Vmax (pmole hr−1). Activity rates are per reaction well (each containing 0.5 mg soil), and Vmax values were later calculated per g soil OM. Information is provided on each curve including the sample treatment (column), coefficient of determination (r2) and enzyme kinetic parameters. Abbreviations for enzyme names (Y-axis) match those in the main document

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Ember M. Morrissey
    • 1
  • David J. Berrier
    • 1
  • Scott C. Neubauer
    • 1
    • 2
  • Rima B. Franklin
    • 1
  1. 1.Department of BiologyVirginia Commonwealth UniversityRichmondUSA
  2. 2.Baruch Marine Field LaboratoryUniversity of South CarolinaGeorgetownUSA

Personalised recommendations