Early Stages Of Incubation Research Articles

Ammonia Volatilization in Acidic Mine Soils Applied with Livestock Manure Compost and Liming Materials

To investigate the possibility of ammonia volatilization in mine lands limed, we conducted an incubation experiment with treating livestock manure compost as an organic fertilizer and dolomite and oyster shell as a liming material. For trapping ammonia volatilized, installing boric acid in a closed system was efficient, with a recovery of 101.2±3.7%. Treating compost and liming material increased soil pH to a range of 5.75-5.88 for a metal-mine soil and 6.02-6.06 for a coal-mine soil. Ammonium-N in soils decreased rapidly with time during early stage of incubation, but nitrate-N changed little. Accumulated ammonia volatilization during incubation was negligible, less than 0.3 mg N kg-1, and only 0.4-0.5% of ammonium-N was volatilized during incubation. Ammonium fixation by clay minerals and immobilization by soil microbes possibly account for the decrease in concentration of ammonium-N. From these results, we concluded that nitrogen loss by ammonium volatilization would be significantly low when acidic mine soils treated with livestock manure compost and liming materials were neutralized to slightly acidic condition. Cumulative ammonia volatilization in (a) metal and (b) coal mine soils after treating compost (Com), compost and dolomite (Com+Dol), and compost and oyster shell (Com+Oys).

Effects of Graphene on Bacterial Community Diversity and Soil Environments of Haplic Cambisols in Northeast China

Graphene is the thinnest and toughest two-dimensional nanomaterial yet discovered. However, it inevitably enters the biosphere, where it may pose potential risks to ecosystems. We investigated the impact of applied graphene concentrations on bacterial community diversity, physicochemical properties, and enzyme activities of Haplic Cambisols, the zonal soil of Northeastern China. Soils receiving 0, 10, 100, or 1000 mg kg−1 of graphene were incubated for 7, 15, 30, 60, or 90 days. Adding graphene significantly increased the community richness and diversity index of the bacterial community in Haplic Cambisols, as well as their abundances, but this impact varied with graphene concentration and incubation time. Compared with 0 mg kg−1 of graphene applied, soil bacteria abundance and diversity increased significantly during early stages of incubation (i.e., 7 and 15 days) under different concentrations of graphene, and was inhibited or remained unchanged by a longer incubation time, reaching a minima at 60 days but then following an upward trend. Graphene treatments influenced the bacterial community structure and metabolic function in Haplic Cambisols, and the bacterial community’s metabolic regulation mechanism varied with both incubation time and graphene concentration. The rank order of bacterial similarity in soils treated with graphene was 15 > 7 > 30 > 60 > 90 days. Throughout the incubation periods, except for a few unidentified bacteria, the relative abundances of Proteobacteria and Acidobacteria in the soil samples were the highest, with the number of Pseudomonas of Proteobacteria being particularly large. The rank order of bacterial abundance at the phylum level in Haplic Cambisols was 15 > 7 > 30 > 90 > 60 days. Graphene also influenced bacterial community diversity by affecting several key soil environmental factors, such as organic matter and hydrolytic nitrogen contents, as well as urease and catalase activities.

Mineralization of plant residues and native soil carbon as affected by soil fertility and residue type

Crop residue return is an effective and low-cost agricultural approach for soil organic carbon (SOC) sequestration. Yet, it is largely unknown to what extent the soil fertility and residue type affect the mineralization of maize (Zea mays L.) residue carbon (C) and the decomposition of native SOC. Therefore, a better understanding of the mineralization of C derived from residues and its priming on native SOC is crucial to accurate assessment of the benefits of crop residue returning in agricultural systems. A 360-day laboratory incubation experiment was carried out with a Cambisol of low and high fertilities amended with three types of 13C-labeled maize residues (root, stem, leaf). The abundance of 13C (δ13C) in the soil samples was measured during different incubation stages. The results showed that the total mineralization of residue C was significantly higher in the low fertility soil than in the high fertility soil, but there were no significant differences among residue types. For the high fertility soil, all the residue types induced a negative priming on native SOC mineralization during the early incubation stage, but a significant total positive priming by the end of incubation, whereas for the low fertility soil, there was no significant effect of residue return on SOC mineralization. The accumulated priming by the end of incubation did not vary across residue types. Moreover, the sum of mineralization of residue C and native SOC in the high fertility soil was 1.4 times as large as that in the low fertility soil. We conclude that mineralization of crop residue C and native SOC is affected by soil fertility rather than residue type.

Non-invasive characterization of chick embryo body and cardiac movements using near infrared light

Embryonic movements, body and cardiac activity, are important physiological phenomena for chick embryo development. Currently, there is no complete non-invasive method for simultaneously quantifying chick embryonic body motility and cardiac rhythm during incubation. This study investigates the use of a near infrared sensor to simultaneously monitor embryonic body and cardiac movements. Light brown chicken eggs (ROSS 308) were incubated for chick embryos activity signals measurement from day 6 to 19. Signal features (peak frequencies and signal energy) of chick embryo periodical activity were extracted to quantify both body and cardiac movements using fast Fourier transform and numerical integration. Two types of body movement were found throughout the whole incubation period. During the early stage of incubation, the movement was periodic; with the pattern differing between embryos. In the mid to late stages of incubation, movements were irregular and had a lower frequency compared to the periodic motion. Heart rates throughout the incubation period varied from 3.8 to 4.8 Hz, while heart beat strength sharply increased during incubation, peaking at day 13 to 14, and then subsequently subsiding. These results indicate that near infrared sensing, combined with signal processing, has the potential to monitor embryo motility and cardiac rhythm that could be used in developmental physiology, cardiovascular medicine and precision poultry production systems.

Tolerance of Sulfolobus SMV1 virus to the immunity of I-A and III-B CRISPR-Cas systems in Sulfolobus islandicus

ABSTRACTSulfolobus islandicus Rey15A encodes one Type I-A and two Type III-B systems, all of which are active in mediating nucleic acids interference. However, the effectiveness of each CRISPR system against virus infection was not tested in this archaeon. Here we constructed S. islandicus strains that constitutively express the antiviral immunity from either I-A, or III-B, or I-A plus III-B systems against SMV1 and tested the response of each host to SMV1 infection. We found that, although both CRISPR immunities showed a strong inhibition to viral DNA replication at an early stage of incubation, the host I-A CRISPR immunity gradually lost the control on virus proliferation, allowing accumulation of cellular viral DNA and release of a large number of viral particles. In contrast, the III-B CRISPR immunity showed a tight control on both viral DNA replication and virus particle formation. Furthermore, the SMV1 tolerance to the I-A CRISPR immunity did not result from the occurrence of escape mutations, suggesting the virus probably encodes an anti-CRISPR protein (Acr) to compromise the host I-A CRISPR immunity. Together, this suggests that the interplay between viral Acrs and CRISPR-Cas systems in thermophilic archaea could have shaped the stable virus-host relationship that is observed for many archaeal viruses.

Microbial Interactions With Dissolved Organic Matter Drive Carbon Dynamics and Community Succession.

Knowledge of dynamic interactions between natural organic matter (NOM) and microbial communities is critical not only to delineate the routes of NOM degradation/transformation and carbon (C) fluxes, but also to understand microbial community evolution and succession in ecosystems. Yet, these processes in subsurface environments are usually studied independently, and a comprehensive view has been elusive thus far. In this study, we fed sediment-derived dissolved organic matter (DOM) to groundwater microbes and continually analyzed microbial transformation of DOM over a 50-day incubation. To document fine-scale changes in DOM chemistry, we applied high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and soft X-ray absorption spectroscopy (sXAS). We also monitored the trajectory of microbial biomass, community structure and activity over this time period. Together, these analyses provided an unprecedented comprehensive view of interactions between sediment-derived DOM and indigenous subsurface groundwater microbes. Microbial decomposition of labile C in DOM was immediately evident from biomass increase and total organic carbon (TOC) decrease. The change of microbial composition was closely related to DOM turnover: microbial community in early stages of incubation was influenced by relatively labile tannin- and protein-like compounds; while in later stages the community composition evolved to be most correlated with less labile lipid- and lignin-like compounds. These changes in microbial community structure and function, coupled with the contribution of microbial products to DOM pool affected the further transformation of DOM, culminating in stark changes to DOM composition over time. Our study demonstrates a distinct response of microbial communities to biotransformation of DOM, which improves our understanding of coupled interactions between sediment-derived DOM, microbial processes, and community structure in subsurface groundwater.

Recalcitrant carbon controls the magnitude of soil organic matter mineralization in temperate forests of northern China

BackgroundThe large potential of the soil organic carbon (SOC) pool to sequester CO2 from the atmosphere could greatly ameliorate the effect of future climate change. However, the quantity of carbon stored in terrestrial soils largely depends upon the magnitude of SOC mineralization. SOC mineralization constitutes an important part of the carbon cycle, and is driven by many biophysical variables, such as temperature and moisture.MethodsSoil samples of a pine forest, an oak forest, and a pine and oak mixed forest were incubated for 387 days under conditions with six temperature settings (5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C) and three levels of soil moisture content (SMC, 30%, 60%, 90%). The instantaneous rate of mineralized SOC was periodically and automatically measured using a Li-Cor CO2 analyzer. Based on the measured amount of mineralized SOC, carbon fractions were estimated separately via first-order kinetic one- and two-compartment models.ResultsDuring the 387 day incubation experiment, accumulative mineralized carbon ranged from 22.89 mg carbon (C) ·g− 1 SOC at 30 °C and 30% SMC for the mixed forest to 109.20 mg C·g− 1 SOC at 15 °C and 90% SMC for the oak forest. Mineralized recalcitrant carbon varied from 18.48 mg C·g− 1 SOC at 30 °C and 30% SMC for the mixed forest to 104.98 mg C·g− 1 SOC at 15 °C and 90% SMC for the oak forest, and contributed at least 80% to total mineralized carbon.ConclusionsBased on the results of this experiment, the soil organic matter of the pure broadleaved forest is more vulnerable to soil microbial degradation in northern China; most of the amount of the mineralized SOC derived from the recalcitrant carbon pool. Labile carbon fraction constitutes on average 0.4% of SOC across the three forest types and was rapidly digested by soil microbes in the early incubation stage. SOC mineralization markedly increased with soil moisture content, and correlated parabolically to temperature with the highest value at 15 °C. No significant interaction was detected among these variables in the present study.

Responses of organic carbon mineralization and priming effect to phosphorus addition in paddy soils

To understand the coupled controlling of carbon (C) and phosphorus (P) on the minera-lization of soil organic carbon and amended substrates in paddy soil, we investigated the effects of P addition on the decomposition of organic carbon and its induced priming effect by using 13C isotope probing technique in microcosm. The results showed that P addition accelerated the release of CO2 but inhibited the release of CH4, leading to 53.1% reduction of total accumulated CH4 and 70.5% reduction of the 13CH4 derived from exotic glucose-13C. P addition altered the carbon distribution during the microbial turnover progress, with 3.6% of glucose-13C being transferred into the labile carbon pool, therein significantly increased potential of the mineralization rate of exogenous C. A transient negative priming effect was observed in the early stage of incubation. With time prolonging, the priming effect on CO2 emission (PECO2) generally increased and then decreased after a peak. The priming effect on CH4 emission (PECH4) kept increasing and finally fluctuated at a relative stable value until the end of the experiment (100 days). P addition increased PECO2 by 32.3% but reduced PECH4 by 93.4%. Results from the RDA and Pearson analysis showed that electric conductivity, oxidation-reduction potential and dissolved organic carbon significantly affected soil C mineralization. There were significantly negative correlations between available phosphorus (Olsen-P) and 13CH4, and between Olsen-P and PECH4. In conclusion, with the addition of exogenous organic matter, P application could reduce CH4 emissions and inhibit its priming effect, acce-lerate the mineralization of SOC, probably improve the nutrient supply, and thus enhance the avai-lability of organic C and promote C cycling in paddy soil.

Effects of labile carbon and phosphorus addition on N transformations with N‐ vs. non‐N‐fixing tree plantations

AbstractPhosphorus (P) is the primary factor limiting soil organic matter (SOM) decomposition and carbon (C) storage in the tropical P‐deficient plantations. However, the mineralization of SOM derived from N‐fixing and non‐N‐fixing plantations may respond differently to P addition within the laboratory‐ or field‐based incubation experiment. In this study, the effects of P addition (+P) combined with glucose (+Glu) on soil N mineralization within Eucalyptus urophylla (EU) and Acacia auriculiformis (AA) plantations were evaluated using a 60‐d laboratory aerobic incubation assay in subtropical China. The results showed that Glu addition significantly affected the net N mineralization and nitrification in both EU and AA plantations. In the 7th day incubation, +Glu treatment enhanced the N mineralization, whereas +Glu+P dramatically accelerated the N immobilization in EU plantation. However, +Glu+P treatment increased N mineralization while +Glu enhanced N immobilization in AA plantation, suggesting that P addition greatly affected the direction of N transformation within different plantations under the labile C input in the early stage of incubation. However, in the 15th day incubation, +Glu increased while +Glu+P greatly reduced the N immobilization in EU plantation. On the contrary, +Glu promoted while +Glu+P further accelerated the N immobilization in AA plantations, indicating that P addition had the contrasting effects on N immobilization within EU and AA plantations. After the 15th day incubation, Glu addition further facilitated the N immobilization in two plantations. Although +Glu increased the fungi and bacteria PLFA biomass, +Glu+P significantly increased F/B ratios, which may contribute to the direction and magnitude of N transformations in two plantations. However, in these two plantation forests with low soil P availability, single P addition would not significantly alter the N mineralization mediated by microbe in the laboratory incubation experiment without the labile C input. Therefore, the significant effects of P addition on the N mineralization or immobilization varied with the incubation stage and plantation types. We recommend that the P availability has profound implications on SOM decomposition and C sequestration in subtropical plantations.

Effects of technogenic pollutants on chicken embryos

Abstract Increasing interest in nanomaterials can be explained by their broad involvement in many fields of industry and medicine. It is known that carbon black and crysotile asbestos behave like nanosized objects. They are wide spread in environment and have close contact with living organisms. The aim of our study was to define the effects of carbon black and crysotile asbestos on structures of the developing organism. We used chicken embryos as a model for our study. Total amount of 77 eggs was divided in three groups: one control and two experimental with introduced carbon black and asbestos respectively. Researched materials were injected in the yolk on the third day of incubation and tissues for study were taken during early, middle and late stages of incubation. Histological and electron microscopy methods were used. Carbon black and asbestos introduction caused underdevelopment of embryos and vessels depletion in blood islands of the yolk sac. Asbestos slowed down angiogenesis. Soot particles caused integrity violation of vessels and led to extravasation. The manifestations of soot influence were damages to blood circulatory system and structural disorders on cellular level. Introduction of chrysotile asbestos mostly resulted in compensatoryadaptive reactions like increasing in hematopoiesis and transcytosis in endotheliocytes.

Sexing of chicken eggs by fluorescence and Raman spectroscopy through the shell membrane.

In order to provide an alternative to day-old chick culling in the layer hatcheries, a noninvasive method for egg sexing is required at an early stage of incubation before onset of embryo sensitivity. Fluorescence and Raman spectroscopy of blood offers the potential for precise and contactless in ovo sex determination of the domestic chicken (Gallus gallus f. dom.) eggs already during the fourth incubation day. However, such kind of optical spectroscopy requires a window in the egg shell, is thus invasive to the embryo and leads to decreased hatching rates. Here, we show that near infrared Raman and fluorescence spectroscopy can be performed on perfused extraembryonic vessels while leaving the inner egg shell membrane intact. Sparing the shell membrane makes the measurement minimally invasive, so that the sexing procedure does not affect hatching rates. We analyze the effect of the membrane above the vessels on fluorescence signal intensity and on Raman spectrum of blood, and propose a correction method to compensate for it. After compensation, we attain a correct sexing rate above 90% by applying supervised classification of spectra. Therefore, this approach offers the best premises towards practical deployment in the hatcheries.

Increased Incidence of Enterococcal Infection in Nonviable Broiler Chicken Embryos in Western Canadian Hatcheries as Detected by Matrix-Assisted Laser Desorption/Ionization-Time-of-Flight Mass Spectrometry.

The emergence of enterococcal infections in neonatal broiler chickens in the poultry industry has become common in many countries, including Canada. The objective of this study was to examine the bacterial infections in nonviable broiler chicken embryos in three western Canadian poultry hatcheries using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The pattern of embryo mortality that occurred during incubation and the breakout analysis results were similar in all three hatcheries. The majority of embryo mortality occurred during the late stage of incubation (35.08%), followed by the early stage of incubation (15.35%). The breakout analysis showed that 65.82% of swabs had at least one type of bacterial growth while 34.17% of swabs were negative for bacterial isolation. Of those 65.82% swabs with bacterial growth, 34.3% of swabs yielded a mixed bacterial population while 31.52% yielded one type of bacterial growth. The frequency of bacterial isolation from hatch debris (60%-75%) increased with the age of broiler breeders. MALDI-TOF MS was able to provide genus-level identification of 83.13% of isolates among all bacterial types isolated. MALDI-TOF MS identified Enterococcus and Escherichia coli isolates with 97.18% and 100% accuracy at species level, respectively, whereas Staphylococcus species were identified with 62.59% accuracy. The congruence between MALDI-TOF MS identification and 16S rRNA or cpn60 universal gene target sequencing was 100% or 90%, respectively. Of all bacteria isolated, Enterococcus species (29.71%) were the most prevalent, followed by E. coli (19.46%). About 56% of E. coli-infected samples were coinfected with Enterococcus species. Among all Enterococcus species isolated, Enterococcus faecalis (79.58%) was the most prevalent, followed by Enterococcus faecium (8.1%). Overall, our study showed that Enterococcus-associated embryo mortality was predominant in all three hatcheries investigated and suggests that MALDI-TOF MS technology can be applied to identify bacteria such as Enterococcus species isolated from poultry.

Exogenous Nitrogen Addition Reduced the Temperature Sensitivity of Microbial Respiration without Altering the Microbial Community Composition.

Atmospheric nitrogen (N) deposition is changing in both load quantity and chemical composition. The load effects have been studied extensively, whereas the composition effects remain poorly understood. We conducted a microcosm experiment to study how N chemistry affected the soil microbial community composition characterized by phospholipid fatty acids (PLFAs) and activity indicated by microbial CO2 release. Surface and subsurface soils collected from an old-growth subtropical forest were supplemented with three N-containing materials (ammonium, nitrate, and urea) at the current regional deposition load (50 kg ha-1 yr-1) and incubated at three temperatures (10, 20, and 30°C) to detect the interactive effects of N deposition and temperature. The results showed that the additions of N, regardless of form, did not alter the microbial PLFAs at any of the three temperatures. However, the addition of urea significantly stimulated soil CO2 release in the early incubation stage. Compared with the control, N addition consistently reduced the temperature dependency of microbial respiration, implying that N deposition could potentially weaken the positive feedback of the warming-stimulated soil CO2 release to the atmosphere. The consistent N effects for the surface and subsurface soils suggest that the effects of N on soil microbial communities may be independent of soil chemical contents and stoichiometry.

Impact of the Isolation Source on the Biofilm Formation Characteristics of Bacillus cereus.

The human pathogen and food spoiler Bacillus cereus can form biofilms that act as a persistent source of contamination, which is of public health concern. This study aimed to understand how the source of isolation might affect the behavior of biofilm formation. Biofilm formation abilities of 56 strains of B. cereus isolated from different environments, including human food poisoning, farm, and food, were determined. Crystal violet assay results revealed significant (p < 0.05) differences in biofilm formation abilities among the strains isolated from different sources only at an early stage of incubation. However, strain origin showed no impact on later stage of biofilm formation. Next, correlation of the group of isolates on the basis of their biofilm-forming abilities with the number of sessile cells, sporulation, and extracellular polymeric substance (EPS) formation was determined. The number of sessile cells and spores in biofilms was greatly influenced by the groups of isolates that formed dense, moderate, and weak biofilms. The contribution of extracellular DNA and/or proteins to EPS formation was also positively correlated with biofilm formation abilities. Our results that the source of isolation had significant impact on biofilm formation might provide important information to develop strategies to control B. cereus biofilm formation.

In situ synthesis of osteoconductive biphasic ceramic coatings on Ti6Al4V substrate by laser-microwave hybridization

Microwave heating is an efficient alternative approach for synthetic chemistry with many distinctive advantages of high heating rate, selective and homogeneous heating. In this study, a new laser-microwave hybridization method, which comprises laser micropatterning, microwave heating and in situ synthesis has been developed to produce titania/hydroxyapatite/tricalcium phosphate (TiO2/HA/TCP) composite coating on titanium alloy (Ti6Al4V) substrate. The composite coating with a fine porous network microarchitecture was selectively produced on the Ti6Al4V surface by laser ablation and alkaline treatment. Using TiO2 sol-gel and mixed powders of calcium carbonate (CaCO3) and dicalcium phosphate dihydrate (CaHPO4·2H2O), the composite coating synthesized at a temperature of 800°C in a short time of 20min exhibited homogeneous microstructure, strong hydrophilicity and good adhesion strength of 34MPa. The in vitro apatite-forming capability of the coating was examined by immersing the coated Ti6Al4V specimen into a simulated body fluid (SBF) for up to 7days. Biodissolution was observed in the early stage of incubation, followed by apatite precipitation. The quantity and size of the apatite globules increased over time. After 7days of immersion, the coating surface was nearly covered by a layer of bone-like apatite, showing a significant improvement of its osteoconductive property over the uncoated sample. The laser-microwave hybridization provides an efficient route to synthesize HA/TCP based coatings for bioactivity enhancement, and serves as an effective sterilization tool for implant materials.

Increasing Rates of Biochar Application to Soil Induce Stronger Negative Priming Effect on Soil Organic Carbon Decomposition

Although the understanding of biochar stability in soil has improved in recent years, there is a lack of knowledge about how both the soil and biochar carbon (C) mineralisations are affected as a function of biochar amount applied to soil. Thus, increasing amounts of biochar were added to a Quartzipsamment in order to evaluate its priming effect on soil organic carbon (SOC) decomposition. We hypothesised that biochar will increase negative priming on native SOC mineralisation as function of its application rate to soil. The biochar was produced from sugarcane straw through slow pyrolysis at 450 °C, and a laboratory incubation was conducted for 90 days with the following treatments: soil-alone (C3 source), biochar-alone (C4 source) and soil with biochar at rates equivalent to 0.4% (T1), 0.8% (T2) and 1.9% (T3) (w/w). In the first day of incubation, biochar amendment reduced soil C mineralisation rates from 58 to 88% compared to the soil-alone as a function of increasing biochar application rates. This reduction was mainly attributed to the mineralisation of easily available substrates from incomplete pyrolysis, which were preferentially used by soil micro-organisms at early stages of incubation. This effect, however, subsided after 7 days of incubation and it was not sufficient to induce co-metabolism of SOC decomposition, which were 43% (T1)–71% (T3) lower compared to the control (soil-alone) after 90 days of incubation. This was reflected in the priming effect data, which confirmed the hypothesis that increasing application rates of biochar to soil induce stronger negative priming on SOM mineralisation. The predicted size of recalcitrant biochar C pool varied from 98.8% (T1) to 99.9% (T3) of the total biochar C with respective mean residence time of 454 and 1539 years. It was concluded that increasing rates of biochar application to soil induce stronger negative priming effect on SOC due to the higher proportional quantity of biochar labile C and preferential utilisation of this easily available C source by micro-organisms. However, the size and long residence time of the recalcitrant C pool of biochar confirm its stability in soil, thus being considered an opportunity for C sequestration in OC-poor soils. Additionally, this study draws encouraging perspectives on the evaluation of sugarcane straw as a chemical feedstock and an alternative biofuel through pyrolysis, providing appreciable amounts of a renewable product with a great potential for carbon storage.

Excessive input of phosphorus significantly affects microbial Fe(III) reduction in flooded paddy soils by changing the abundances and community structures of Clostridium and Geobacteraceae

Microbial Fe(III) reduction can make an excellent contribution to the bioremediation of contaminated environments and potentially reduce methanogenesis. Excessive input of phosphorus (P) by P fertilizer application and eutrophied irrigation water might have a substantial influence on the process of microbial Fe(III) reduction in flooded paddy soils. To evaluate the effect of P application on microbial Fe(III) reduction, the responses of Clostridium and Geobacteraceae communities to different concentrations of P addition (CK: 0mmolPkg−1 soil; P1: 3.3mmolPkg−1 soil; P2: 20mmolPkg−1 soil) were investigated in anaerobically incubated paddy slurries. P addition significantly inhibited Fe(III) reduction during the early stage of incubation (from days 0 to 20). Compared with the CK treatment, the maximum Fe(III) reduction rate (Vmax) in treatments P1 and P2 remarkably decreased by 0.281 and 0.439mg·g−1·d−1, respectively. However, the addition of P had no significant effect on Fe(III) reduction during the later stage of incubation (after 20days). The abundances of Clostridium and Geobacteraceae were suppressed by P addition, and the suppression effect was more obvious with higher P concentration. P addition significantly changed the community structures of Clostridium and Geobacteraceae during the entire incubation. The communities of Clostridium and Geobacteraceae were closely correlated with the process of Fe(III) reduction. In conclusion, P addition could inhibit the microbial reduction of Fe(III) during the early stage of incubation by reducing the abundances and altering the community structures of Clostridium and Geobacteraceae, however, the inhibition could be eliminated with increased incubation time. This study demonstrates that soil microbial communities are sensitive to excessive P application, which can jointly impact relevant biogeochemical processes in flooded paddy soils.

Maize Stover Biochar Accelerated Urea Hydrolysis and Short-term Nitrogen Turnover in Soil

The study was carried to determine the labile carbon contents in biochar pyrolyzed under different temperatures and its effect on urea hydrolysis rate. Corn stovers were pyrolyzed at highest temperature of 300°C, 500°C and 700 °C to produce fresh biochar. Soil incubation experiment was conducted with biochar application rate of 0% and 2% with presence of urea. The results showed that biochars accelerated urea hydrolysis, and high temperature pyrolyzed biochar have more significant effect on soil pH enhances and acceleration of urea hydrolysis than biochar pyrolyzed at low temperature. Moreover, biochar produced at 300°C contains relative high concentration of labile carbon, and 43-64% of labile carbons were oxidized within 40 days incubation. The labile carbon in biochars also leaded microbes thrives and resulted in accelerate short-term N turnover. i.e. at early stage of incubation, fresh biochar increased mineralization of soil N by 79-449 mg•kg−1, and matured biochar by 30-61 mg•kg−1, but microbial immobilization effect was observed in fresh biochar-amended soil at the end of incubation. We concluded that aged biochar is suitable for simultaneous soil amendment with urea rather than newly produced biochar as it can promote available N accumulation in short time thus increase the risk of inorganic nitrogen leaching loss.

A potential mechanism for degradation of 4,5-dichloro-2-(n-octyl)-3[2H]-isothiazolone (DCOIT) by brown-rot fungus Gloeophyllum trabeum.

This study aims to investigate the biodegradation of 4,5-dichloro-2-(n-octyl)-3[2H]-isothiazolone (DCOIT) by a brown-rot fungus Gloeophyllum trabeum as well as the involved mechanism. In the present study, the retentions of DCOIT in treated Masson pine (Pinus massoniana) (MP) chips were determined periodically after incubation with G. trabeum. Then a Fenton-like reaction, known as the chelator-mediated Fenton (CMF) chemistry was used to degrade DCOIT that mimics the degradation pathway of DCOIT by typical brown-rot fungi, and the degradation intermediates were further analyzed. The results demonstrated that DCOIT was rapidly depleted in the early stages of incubation by G. trabeum. The CMF treatment was shown to oxidatively decompose DCOIT by producing reactive oxygen species. This evidence suggests that the CMF chemistry employed by brown-rot fungi contributes to the rapid depletion of DCOIT during G. trabeum exposure, although this does not rule out other possible mechanisms for the biodegradation of DCOIT. The new findings give new insights into the mechanism for the biodegradation of organic biocides, and potentially provide an efficient approach for the removal of organic pollutants in the contaminated water.

Great Powers-Africa Security Relations and War on Terrorism: Extrapolations from 'Operation Serval' in Mali

The terrorist insurgency in Mali was an international jigsaw and a litmus test for African security mechanism under Great Powers’ influence in recent times. The post-bin Ladin terrorist upsurge rekindled anxiety that the assassination of al-Qaeda leader Osama bin Ladin did not put an end to international terrorism and that Great Powers can intervene in African states under the guise of war on terrorism as French “Operation Serval” in Mali demonstrates. The paper’s objective is to empirically underscore the politico-economic motivations, strengths and weaknesses of Great Powers’ military intervention in Africa under the guise of war on terrorism. From the theoretical foundation of interdependence of nations, the author argued that intelligence-sharing at early warming stage of terrorist incubation matched with astute diplomatic efforts and respect for people’s rights remain more salutary and effective collective measures to nip on the bud external intervention against terrorism in sovereign states.