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Hu G.,CAS Shenyang Institute of Applied Ecology | Hu G.,University of Chinese Academy of Sciences | He H.,CAS Shenyang Institute of Applied Ecology | Zhang W.,CAS Shenyang Institute of Applied Ecology | And 6 more authors.
Soil Biology and Biochemistry | Year: 2016

Developing an understanding of the transformation kinetics of amino acids in soil is of fundamental importance to probe into the stabilization and decomposition processes central to soil organic matter (SOM) cycling. Considering the transitional function of amino acids in SOM turnover, substrate availability controls the formation and decomposition of soil amino acids critically. However, compared to broad knowledge on free amino acid turnover, how the changing bio-availability of carbon (C) and nitrogen (N) influences the accumulation and turnover of proteinaceous amino acids in soil is not well understood. Therefore, a laboratory experiment was conducted in which soil samples were incubated and supplemented weekly with glucose and 15N-labeled inorganic N as either ammonium (NH4+) or nitrate (NO3-). The concentrations of soil amino acids, differentiated into the newly synthesized (15N-labeled) and endogenous (unlabeled) portion, were temporally quantified by an isotope-based high-performance liquid chromatography/mass spectrometric technique.During the incubation, extraneous substrates were rapidly immobilized into soil amino acids as important metabolic constituents. However, the dynamics and maintenance of soil amino acids were determined by changing C and N availability during microbial proliferation rather than static stoichiometry of available substrates. The significantly greater amount of de-novo synthesized amino acids in treatments with NH4+ addition than NO3- addition confirmed that microorganisms preferred the reduced N than the oxidized form due to significantly lower energy and C requirements. The decomposition of endogenous amino acids during the later stages of the incubation indicated that amino acids could partly meet microbial C and energy demand, but the capacity to get decomposed was independent on N species. Therefore, higher rate of extraneous N immobilization in glucose plus NH4+ treatment was closely associated with the net accumulation of amino acids; whereas the formation of new proteinaceous amino acids after weekly additions of glucose plus NO3- was eventually offset by the loss of the endogenous portion, resulting in apparently unchanged amounts of amino acids in the microcosms.Under the two incubation conditions with available C and N addition, both the intrinsic C percentage in molecules and the biosynthetic pathways have minor influence on the turnover pattern of HCl hydrolyzed amino acids. However, the transformation of individual amino acids was significantly correlated throughout the entire incubation. These findings suggested that the turnover of soil amino acids in proteinaceous form was critically interrelated instead of being controlled by the transformation pathways of different free amino acids. Compared to the NH4+ supply, the addition of NO3- enhanced the decomposition of glycogenic amino acid while reduced the degradation of most of ketogenic amino acids, possibly suggesting the important regulating strategy of energy yield on microbial speciation of the N forms. © 2016 Elsevier Ltd.


Zhang B.,CAS Shenyang Institute of Applied Ecology | Zhang B.,University of Chinese Academy of Sciences | Liang C.,University of Wisconsin - Madison | He H.,CAS Shenyang Institute of Applied Ecology | And 2 more authors.
PLoS ONE | Year: 2013

Altitudinally-defined climate conditions provide specific vegetation types and soil environments that could influence soil microbial communities, which in turn may affect microbial residues. However, the knowledge is limited in terms of the degree to which microbial communities and residues present and differ along altitude. In this study, we examined the soil microbial communities and residues along the northern slope of Changbai Mountain, China using phospholipid fatty acid (PLFA) and amino sugar analysis, respectively. Soil samples were taken from five different vegetation belts defined by climates. Principal component analysis (PCA) revealed substantial differences in soil microbial community composition among study sites, appeared to be driven primarily by soil pH and C/N ratio on the first principal component (PC1) which accounted for 50.7% of the total sample variance. The alpine tundra was separated from forest sites on the second principal component (PC2) by a signifiscantly higher amount of fungal PLFA (18:2ω6,9). Soil pH and C/N ratio were also correlated with the ratios of Gram-positive to Gram-negative bacteria (Gm+/Gm-), glucosamine to galactosamine (GluN/GalN), and glucosamine to muramic acid (GluN/MurA). Both total PLFAs and amino sugars were positively correlated with soil organic carbon, inorganic nitrogen, available phosphorus and potassium. We concluded that soil pH and C/N ratio were the most important drivers for microbial community structure and amino sugar pattern, while substrate availability was of great importance in determining the concentrations of microbial communities and residues. These findings could be used to facilitate interpretation of soil microbial community and amino sugar data derived from measurements in latitude or managed forests. © 2013 Zhang et al.


Lu H.,CAS Shenyang Institute of Applied Ecology | Lu H.,Zhejiang University | He H.,CAS Shenyang Institute of Applied Ecology | Zhao J.,Huazhong Agricultural University | And 8 more authors.
Plant and Soil | Year: 2013

Background: Inorganic fertilizer is one of the most important anthropogenic inputs which influences soil nutrient turnover in agricultural ecosystems. However, as the key process involved in the maintenance, transformation and stability of soil nitrogen (N), the incorporation and allocation of fertilizer N between different soil organic N (SON) fractions in a growing season remains largely unknown. Methods: In this study, a field experiment was conducted in triplicate of micro-plots and a total of 200 kg N ha-1 (15 N-labeled (NH4)2SO4, 98 atom %) was applied as a basal dressing and two top dressings, at jointing and filling stages, respectively, to a maize crop during one growing season. The distribution and seasonal dynamics of fertilizer N in different SON fractions (i.e., amino acids, amino sugars, hydrolyzable ammonium N and acid insoluble-N) were measured by liquid/gas chromatography-mass spectrometry (LC/GC-MS) and element analysis-combustion-isotope ratio mass spectrometry (EA-C-IRMS) techniques. Path analysis was used to evaluate the transformation processes between organic N fractions derived from fertilizer and N supply strategy in soil-plant system. Results: The accumulation of fertilizer-derived N in different organic fractions was season-specific. At jointing stage, preferential enrichment of 15 N was found in soil amino acids plus amino sugars, indicating the active biological immobilization of basal dressing fertilizer N. Nevertheless, there is still a small proportion of fertilizer N stabilized in the acid insoluble fraction. The accumulation of the residual fertilizer N in hydrolyzable ammonium N reached a maximum at filling stage and then declined significantly, implying the rapid release of the fertilizer N remained in mineral forms. The contents of amino acids changed slightly, but they played a very important role in mediating SON transformation. Conclusion: The hydrolyzable ammonium N was a temporary pool for rapid fertilizer N retention and simultaneously was apt to release N for crop uptake in the current season. In contrast, the amino acids could serve as a transitional pool of available N in the soil-crop system, while the acid insoluble fraction was as a stable pool of fertilizer N. Importantly, there is an interim shift among different pools to maintain soil N turnover; hence N in the amino acid fraction mediates N supply and the depolymerization of SON constituents controls the proceeding of fertilizer N cycling in the soil-plant system. © 2013 Springer Science+Business Media Dordrecht.


Zhang W.,CAS Shenyang Institute of Applied Ecology | Han Y.-J.,CAS Shenyang Institute of Applied Ecology | Han Y.-J.,University of Chinese Academy of Sciences | He H.-B.,CAS Shenyang Institute of Applied Ecology | And 3 more authors.
Chinese Journal of Applied Ecology | Year: 2012

A soil incubation test was conducted to study the quantitative changes of three amino sugars(glucosamine, muramic acid, and galactosamine) derived from microbes under drying and wetting cycle, and to analyze the relative contribution of soil bacteria and fungi to the turnover of soil organic matter by using the measured glucosamine/muramic acid ratio. Under continuous wetting, the degradation of bacteria-derived muramic acid was faster than that of fungi-derived glucosamine, and the degradation rate of galactosamine was the lowest. Drying and wetting cycle altered the degradation characteristics of the three amino sugars. As compared with that under continuous wetting, the degradation rate of bacteria-derived muramic acid at the prophase of drying and wetting was faster than that of fungi-derived glucosamine, and, with the increasing frequency of drying and wetting cycle, the degradation rate of fungi-derived glucosamine was faster than that of bacteria-derived muramic acid. These results indicated that drying and wetting cycle changed the course of the microbial transformation of soil amino sugar-derived nitrogen.


Zhang W.,CAS Shenyang Institute of Applied Ecology | Zhang X.-D.,CAS Shenyang Institute of Applied Ecology | Zhang X.-D.,National Field Observation and Research Station of Shenyang Agroecosystems | He H.-B.,CAS Shenyang Institute of Applied Ecology | And 2 more authors.
Chinese Journal of Ecology | Year: 2010

This paper summarized the research progress in the effects of drying/wetting cycles on the mineralization, transformation, and losses of soil nitrogen, and on the soil aggregate structure, swelling-shrinking characteristics, microbial activity, and microbial community. It was indicated that soil drying/wetting cycles could affect the mineralization and losses of soil nitrogen, and the transformation of soil nitrogen was closely related to the soil aggregate structure, swellingshrinking characteristics, microbial activity, and microbial community. The future research directions were also proposed, with the focus on the relationships between soil nitrogen transformation and soil physical and microbial characters, especially the microbial transformation of fertilizer nitrogen, so as to provide theoretical references for the further study of soil nitrogen transformation processes and mechanisms.


Lu H.,CAS Shenyang Institute of Applied Ecology | Lu H.,University of Chinese Academy of Sciences | He H.,CAS Shenyang Institute of Applied Ecology | Zhang X.,CAS Shenyang Institute of Applied Ecology | Zhang X.,National Field Observation and Research Station of Shenyang Agroecosystems
Advanced Materials Research | Year: 2012

Fertilizer applications to soil are widely known to be the most important anthropogenic sources to influence soil N turnover in agricultural ecosystems. More information is required on the relationships between soil organic N (SON) forms in order to predict the maintenance, transformation and stability of soil N. Accordingly, 15N-labeled (NH 4) 2SO 4 (totally 200 kg N/ha) was applied to a maize crop throughout the entire growing period to investigate the distribution and the dynamics of fertilizer-derived N in hydrolyzable-NH 3 fraction by measuring the labeled N in them. The accumulation of 15N in hydrolyzable-NH 3 fraction was time-dependent although the total N concentration changed only slightly. The transformation of the residual fertilizer N to hydrolyzable-NH 3- 15N was maximal during the silking and grain filling stages, suggesting the fertilizer N was immobilized at an early stage during the growing period. The rapid decrease of 15N in hydrolyzable-NH 3 pool indicated that hydrolyzable-NH 3- 15N was a temporary pool for fertilizer N retention and was able to release fertilizer N for uptake by the current crop. © (2012) Trans Tech Publications, Switzerland.

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