TY - JOUR

T1 - Microbial utilization of mineral-associated nitrogen in soils

AU - Turner, Stephanie

AU - Meyer-Stüve, Sandra

AU - Schippers, Axel

AU - Guggenberger, Georg

AU - Schaarschmidt, Frank

AU - Wild, Birgit

AU - Richter, Andreas

AU - Dohrmann, Reiner

AU - Mikutta, Robert

N1 - Funding information: We thank Roger Michael Klatt and Leo M. Condron for the help with preparation and realization of the sampling, Peter C. Almond, Duane A. Peltzer and Sarah J. Richardson for access to the sampling sites, Norman Gentsch and Norbert Bischoff for advice and discussion on setup and results of the incubation experiment and on analysis of gas measurements, Daria Frohloff and Gudrun Mengel-Jung for technical support with the DNA extraction, Florian Stange for discussion of the data and reading the manuscript, and Christian Siebenbürgen for help with graphical issues. The AOB standard for qPCR was kindly provided by the ‘Aquatic Geomicrobiology’ Group, University of Jena, Germany, and the Streptomyces strain for the chiA qPCR standard was kindly provided by the ‘Environmental Microbiology’ Group, TU Bergakademie Freiberg, Germany. Funding was provided by the German Research Foundation (DFG) [ MI 1377/5-2 to R.M. and SCHI 535/11-2 to A.S.].

PY - 2017/1

Y1 - 2017/1

N2 - In soils, a large portion of organic nitrogen (ON) is associated with minerals and thus, possibly stabilized against biological decay. We therefore tested if mineral-associated N is an important N source for soil microorganisms, and which soil parameters control its bioavailability. Microcosm experiments with mineral-associated organic matter, obtained as heavy fraction (HF) via density fractionation, and bulk soil from mineral topsoil of the Franz Josef chronosequence were conducted for 125 days. We examined the effects of O2 status, soil age (differences in mineralogical properties), as well as cellulose and phosphate additions on the turnover of mineral-associated N. Using a combination of activity measurements and quantitative PCR, microbial N transformation rates and abundances of N-related functional genes (amoA, narG, chiA) were determined. Similar or higher values for microbial N cycling rates and N-related functional abundances in the HF compared to bulk soil indicated that mineral-associated N provides an important bioavailable N source for soil microorganism. The turnover of mineral-associated N was mainly controlled by the O2 status. Besides, soil mineralogical properties significantly affected microbial N cycling and related gene abundances with the effect depending on the N substrate type (ON, NH4 + or NO3 −). In contrast, cellulose or phosphate addition hardly enhanced microbial utilization of mineral-associated N. The results of our microcosm study indicate that mineral-associated N is highly bioavailable in mineral topsoils, but effects of the mineral phase differ between N cycling processes.

AB - In soils, a large portion of organic nitrogen (ON) is associated with minerals and thus, possibly stabilized against biological decay. We therefore tested if mineral-associated N is an important N source for soil microorganisms, and which soil parameters control its bioavailability. Microcosm experiments with mineral-associated organic matter, obtained as heavy fraction (HF) via density fractionation, and bulk soil from mineral topsoil of the Franz Josef chronosequence were conducted for 125 days. We examined the effects of O2 status, soil age (differences in mineralogical properties), as well as cellulose and phosphate additions on the turnover of mineral-associated N. Using a combination of activity measurements and quantitative PCR, microbial N transformation rates and abundances of N-related functional genes (amoA, narG, chiA) were determined. Similar or higher values for microbial N cycling rates and N-related functional abundances in the HF compared to bulk soil indicated that mineral-associated N provides an important bioavailable N source for soil microorganism. The turnover of mineral-associated N was mainly controlled by the O2 status. Besides, soil mineralogical properties significantly affected microbial N cycling and related gene abundances with the effect depending on the N substrate type (ON, NH4 + or NO3 −). In contrast, cellulose or phosphate addition hardly enhanced microbial utilization of mineral-associated N. The results of our microcosm study indicate that mineral-associated N is highly bioavailable in mineral topsoils, but effects of the mineral phase differ between N cycling processes.

KW - Functional genes

KW - Microbial nitrogen cycling

KW - Mineral-associated organic matter

KW - Net N mineralization

KW - Priming

KW - Quantitative PCR

UR - http://www.scopus.com/inward/record.url?scp=84994012301&partnerID=8YFLogxK

U2 - 10.1016/j.soilbio.2016.10.010

DO - 10.1016/j.soilbio.2016.10.010

M3 - Article

AN - SCOPUS:84994012301

VL - 104

SP - 185

EP - 196

JO - Soil Biology and Biochemistry

JF - Soil Biology and Biochemistry

SN - 0038-0717

ER -