Coupled abiotic-biotic cycling of nitrous oxide in tropical peatlands

Atmospheric nitrous oxide (N2O) is a potent greenhouse gas thought to be mainly derived from microbial metabolism as part of the denitrification pathway. Here, we report that in unexplored peat soils of Central and South America, N2O production can be driven by abiotic reactions (> 98 %) highly competitive to their enzymatic counterparts. Extracted soil iron positively correlated with in-situ abiotic N2O production determined by isotopic tracers. Moreover, we found that microbial N2O reduction accompanied abiotic production, essentially closing a coupled abiotic-biotic N2O cycle. Anaerobic N2O consumption occurred ubiquitously (pH 6.4-3.7), with proportions of diverse clade II N2O-reducers increasing with consumption rates. Our findings show denitrification in tropical peat soils is not a purely biological process, but rather a 'mosaic' of abiotic and biotic reduction reactions. We predict hydrological and temperature fluctuations differentially affect abiotic and biotic drivers and further contribute to the high N2O flux variation in the region.

Indicators of severity and accentuated personality traits in men with various forms of eczema

Annotation. The purpose of this work is to determine the features of indicators of severity and features of accentuated personality traits in men with various forms of eczema. On the basis of the Military Medical Clinical Center of the Central Region and the Department of Dermatology and Venereal Diseases with a postgraduate course in National Pirogov Memorial Medical University, Vinnytsya, a survey of men of the first adult age (22-35 years) with true (n=34, including 16 with mild and 18 with severe course) and microbial (n=38, including 28 with mild and 10 with severe course) eczema was conducted. The diagnosis of eczema was performed according to the nomenclature of ICD-10. All men with the help of personality questionnaires were assessed by the severity and features of accentuated personality traits by Shmishek. Statistical data processing was performed in the license package “Statistica 5.5” using non-parametric methods of evaluation of the obtained results. The control group of subjects revealed the following percentage distribution of types of accentuation: hyperthymic – in 37.80 %; stuck – in 1.22 %; emotional – in 1.22 %; pedantic – in 3.66 %; anxious – in 1.22 %; cyclothymic – in 10.98 %; demonstrative – in 3.66 %; excitable – in 7.32 %; dysthymic – in 0 %; exalted type – in 14.63 %. In patients with true eczema of mild course: hyperthymic – in 43.75 %; stuck – in 0 %; emotional – in 0 %; meticulous – in 0 %; anxious – in 0 %; cyclothymic – in 0 %; demonstrative – in 6.25 %; excitable – in 0 %; dysthymic – in 6.25 %; exalted type – 6.25 %. In patients with true eczema of severe course: hyperthymic – in 83.33 %; stuck – in 0 %; emotional – in 0 %; meticulous – 5.56 %; anxious – in 0 %; cyclothymic – in 0 %; demonstrative – in 5.56 %; excitable – in 0 %; dysthymic – in 0 %; exalted type – in 11.11 %. In patients with mild microbial eczema: hyperthymic – in 53.57 %; stuck – in 0 %; emotional – in 0 %; meticulous – in 7.14 %; anxious – in 0 %; cyclothymic – in 3.57 %; demonstrative – in 0 %; excitable – in 7.14 %; dysthymic – in 0 %; exalted type – in 7.14 %. In patients with severe microbial eczema: hyperthymic – in 40.00 %; stuck – in 0 %; emotional – in 0 %; meticulous – 10.00 %; anxious – in 0 %; cyclothymic – in 0 %; demonstrative – in 0 %; excitable – in 0 %; dysthymic – in 0 %; exalted type – 10.00 %. Thus, the active use in everyday practice of interviewing and psychological testing of character accentuation are the most important components of adequate assessment of psycho-emotional status of patients with various forms and severity of eczema, which opens prospects for psychoprophylaxis and finding the right ways of correction. Thus, in patients with different forms and severity of eczema, the predominance of accentuation of the nature of the hyperthymic type was established. This allows us to consider this type of accentuation as one of the important criteria for assessing the patient's motivation to see a dermatologist and adherence to treatment, to identify weaknesses in his character, to predict factors that can cause decompensation or psychogenic reactions accompanied by maladaptation.

Effect of Commercial Slow-Release Urea Product on in Vitro Rumen Fermentation and Ruminal Microbial Community Using RUSITEC Technique

Background The objectives of this study were to determine the effect of commercial slow-release urea (SRU) on in vitro fermentation characteristics, nutrient digestibility, gas production, microbial protein synthesis and bacterial community using rumen simulation technique (RUSITEC). The experiment was a completely randomized design with four treatments and four replications of each treatment. Treatments were: control diet (no SRU addition), control diet plus 0.28% SRU (U28), or plus 0.56% SRU (U56), and control diet that was modified for substituting with 0.35% SRU for equavelant soybean protein (MU35; dry matter [DM] basis). The experiment consisted of 8 days of adaptation and 7 days of data and sample collection. Rumen inoculum was obtained from three ruminally fistulated Angus cows fed the same diet to the substrate incubated. Results Digestibility of DM, organic matter (OM), crude protein (CP), fibre and starch was not affected, but daily production of gas (P < 0.07) and methane (P < 0.05) was quadratically changed with increasing SRU supplementation. The increase of SRU addition did not affect fermentation pH and total volatile fatty acid (VFA) production, whereas linearly (P < 0.01) decreased proportion of propionate, and linearly (P < 0.01) increased acetate to propionate ratio and ammonia nitrogen (N) concentration. The microbial N efficiency also linearly (P < 0.03) improved with increasing supplementation of SRU. In comparison with control diet, the dietary substitution of SRU for part of soybean meal increased (P < 0.05) the digestibility of DM, OM and CP and decreased (P < 0.02) the total gas production. The total VFA production and acetate to propionate ratio did not differ between control and MU35, whereas the proportion of butyrate was lower (P < 0.05) and that of branched-chain VFA was greater (P < 0.05) with MU35 than control diet. Total and liquid-associated microbial N production as well as ammonia N concentration were greater (P < 0.03) with MU35 than control diet. Observed OTUs, Shannon diversity index, and beta diversity of the microbial community did not differ among treatments. Taxonomic analysis revealed no effect of adding SRU on the relative abundance of bacteria at the phylum level, while at the genus level, the impact of SRU addition on microbial community was greater with MU35 either for liquid associate bacteria or feed particle-associated bacteria. Conclusions Supplementation of a dairy cow diet with SRU showed potential of increase in ammonia N concentration and microbial protein production, and change fermentation pattern to more acetate production. Adding SRU in dairy cow diet also showed beneficial effect on improving digestibility of OM and fibre. The results suggest that SRU can partially substitute soybean meal in dairy cow diet to increase microbial protein production without impairing rumen fermentation.

Long-Term Bare Fallow Soil Reveals The Temperature Sensitivity of Priming Effect of The Relatively Stabilized Soil Organic Matter

Priming plays an important role in modifying the decomposition of soil organic matter (SOM), but there are large uncertainties in the temperature effect on priming mainly due to the variation in SOM stability. Long-term bare fallow offers a unique opportunity to isolate the relatively stabilized SOM pool and study its properties. We tested the temperature effect on priming of the relatively stabilized SOM pool by incubating soil samples collected from a bare fallow (representing the relatively stabilized SOM) and its adjacent old field (containing both stabilized SOM and labile SOM) at 10 and 20°C for 815 days. We amended the soil samples with C4 maize leaves to distinguish the CO2 source released from the soils (formed under C3 vegetation) and the substrate added (i.e. maize leaves) based on the natural abundance of δ13C. In all cases, there was a positive priming effect on native SOM decomposition when fresh organic matter (maize leaves) was added. The temperature sensitivity of priming effect (calculated as the difference in SOM decomposition due to the addition of maize leaves) in the bare fallow soil and the old field soil was quite different: increasing temperature significantly enhanced the magnitude of priming effect in the bare fallow soil, whereas had no effect on the magnitude of priming effect in the old field soil. The increase of the amount of microbial biomass C by maize leaves application was higher in the bare fallow soil than in the old field soil. Furthermore, for maize leaves-treated soil, temperature increase significantly increased the rate of microbial N mining throughout the incubation in the bare fallow soil, but had minor effect on microbial N mining in the old field soil at the end of incubation. We conclude that the priming effect of the relatively stabilized SOM was sensitive to temperature increase, which may be mainly driven by greater microbial growth and microbial demand for N. This work highlights the vulnerability of stabilized SOM to priming effect under global warming and reveals the potential role of microbes in regulating soil C dynamics under future climate change.

Controls of microbial N cycling in agricultural grassland soils

&lt;p&gt;Fertilization experiments provide insights into elemental imbalances in soil microbial communities and their consequences for soil nutrient cycling. By addition of selected nutrients, other nutrients become deficient and limiting for soil microorganisms as well as for plants. In this study we focused on microbial nitrogen (N) cycling in a long-term nutrient manipulation experiment. In many soils, the rate-limiting step in N cycling is depolymerization of high-molecular-weight nitrogen compounds (e.g., proteins) to oligomers (e.g., peptides) and monomers (e.g., amino acids) rather than the subsequent steps of mineralization (ammonification) and nitrification. The aim of our study was to determine whether nutrient deficiency directly or indirectly &amp;#8211; via changes in plant carbon (C) inputs - affects soil microbial N processing.&lt;/p&gt;&lt;p&gt;We collected soil samples from a fertilization experiment, established in 1946 on a hay meadow close to Admont (Styria, Austria). The field experiment consisted of a full factorial combination of inorganic N, P, and K fertilization and a control with no fertilizers. Furthermore, liming (Ca-addition) and organic fertilizer application treatments (solid manure and liquid slurry) were established. In the experiment, plant biomass is harvested three times per year, inducing strong nutrient limitation in plots that have not received nutrient additions (fully deficient or deficient in a single element). We determined gross rates of microbial protein depolymerization, N-mineralization and nitrification via isotope pool dilution assays with &lt;sup&gt;15&lt;/sup&gt;N-labeled amino acids, NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;, and NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;. We hypothesized that N deficiency (lack of N fertilization) would stimulate microbial N mining (depolymerization), and reduce subsequent N mineralization and nitrification. In contrast, we expected that organic fertilization would alleviate microbial C and N limitations, reducing N depolymerization rates and increasing mineralization and nitrification.&lt;/p&gt;&lt;p&gt;Our results show that organically fertilized and limed soils have significantly lower gross protein depolymerization rates than plots receiving inorganic N. No significant differences were found comparing gross N-mineralization and gross nitrification rates across the different treatments. Given the higher rates of protein depolymerization in inorganically fertilized soils as compared to organically fertilized and limed soils, microbial N processes seem to be controlled by plant C input and/or soil pH rather than by direct soil nutrient availability. However, depolymerization of macromolecular N does not only supply N to the soil microbial community but also organic C. Thus, the reduced plant C input compared to fully fertilized soils may have caused microorganisms to increase their mining for a C-containing energy source, thereby increasing protein depolymerization rates. In summary, this study suggests that long term nutrient deficiency or nutrient imbalances may affect soil nutrient cycling indirectly by changing plant C inputs (via reduced primary production) and/or changing soil pH, rather than directly, by nutrient availability. This further indicates that soil microbial communities are rather C than nutrient limited.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Effects of barley and corn as sources of silage and grain on dry matter intake, ruminal fermentation, and total-tract digestibility in growing beef heifers

The objective of this study was to evaluate the use of barley (BS) or corn (CS) silage when fed with dry-rolled barley (BG), corn (CG), or an equal blend (BCG) of BG and CG for backgrounding cattle. Ruminally cannulated heifers (n=5) were assigned to an incomplete 6 × 6 Latin square design. Treatments contained either BS or CS in combination with BG, CG, or BCG. Samples were collected to determine DMI, ruminal fermentation, total-tract nutrient digestibility, and nitrogen balance. Interactions between cereal silage and cereal grain sources were detected for the molar proportions of propionate and butyrate where the magnitude of change with the type of cereal grain was increased in heifers fed CS relative to BS. Feeding CS increased estimated microbial N production (silage, P = 0.022) and fecal N excretion (silage, P = 0.042) over BS. Diets containing BG had greater DM, OM, starch, and GE digestibility values compared to CG, but values for BCG were not different (grain, P ≤ 0.043). Based on limited silage x grain interactions, use of CS in backgrounding diets may increase microbial N production relative to BS and dry-rolled CG may reduce apparent total-tract nutrient digestibility relative to dry-rolled BG.