First Week Of Incubation Research Articles

Repercussion of Controlled Decomposition Process on Carbon Dynamics and Quality Evaluation in Chicken Manure Pellets

An incubation experiment was conducted to determine the decomposition potential of the chicken manure pellets and to know the nutrient composition. The chicken manure pellets produced from the bedding material of commercially grown broiler farm was tested for decomposition rate through CO2 evolution and nutrient content. The rate of decomposition of poultry manure pellets (CO2 emission) was less during the first week of incubation and linearly enhanced during 2nd and 3rd week after incubation. The rate of emission of CO2 has been reached maximum (150 mg of CO2 per gram per day during the 4th week of incubation. The enhanced CO₂ evolution indicated addition of more organic matter content and balanced steady release of nutrients on incorporation in to soil.

Use of image analysis to assess radial growth of Passalora arachidicola and Nothopassalora personata on solid media

ABSTRACT Despite significant research on early and late leaf spot diseases of peanut, in vitro study of the respective causal agents, Passalora arachidicola and Nothopassalora personata, has been limited due to cultural challenges that make growth of these fungi difficult to quantify with traditional methods. Studies were conducted to evaluate the practicality of image analysis to assess radial growth and tissue volume by correlating these assessments to dry mass. Image analysis was also used to estimate radial growth rates for these fungi over time. Tissue area and volume were significantly correlated to dry mass for P. arachidicola in two separate experiments, and for N. personata when medium had been removed from tissues prior to dry mass assessments. Tissue area densities were the same for P. arachidicola and Pseudocercospora smilacicola, evaluated as a nonstromatal cercosporoid comparison, whereas tissue volume densities were greater for P. archidicola and N. personata than P. smilacicola. A quadratic relationship was observed between radial growth and incubation time for all isolates evaluated. Growth rates of P. arachidicola isolates were 2 to 4 times faster than N. personata during the first week of incubation and slowed over time. Growth rates of NP18R, a phenotype variant of N. personata, increased after neighboring colonies met and was nearly 2.5 times faster than the fastest rates observed for P. arachidicola. These experiments demonstrate that when fungal tissues are observable, image analysis is a useful assessment tool for P. arachidicola and N. personata. Care should be taken to monitor fungal phenotypic changes in these species because phenotype degeneration can affect growth rates.

Green turtle (Chelonia mydas) hatching success at Raine and Heron Islands

Raine Island, the world’s largest green turtle nesting location, has low nest hatching success. The main causes of this low hatching success are thought to be nest destruction by subsequent nesting females, and inundation of nests during high tides and storm surges. But even nests that are protected from nest destruction and inundation appear to have relatively low hatching success, with most of the embryo mortality occurring early in incubation. Here, I compare hatching success and developmental phase of embryo death of protected ‘dry’ nests from Raine Island (RI) with similar nests from Heron Island (HI), a nesting location previously reported as having high hatching success. Nests at both sites were sampled close to the peak time of nesting (December). Twenty-eight nests were sampled at RI and 14 nests at HI. Nest temperatures were cooler during the first week of incubation at HI (median 26.9°C) than at RI (median 30.1°C), but three-days-in-a-row maximum nest temperatures were higher at HI (median 36.0°C) than at RI (median 33.5°C). I found the hatching success of sampled nests at both locations was similar, ~70%, but most embryo death occurred early in incubation at RI (median 16.5%) compared to HI (median 3.8%), but late in incubation at HI (median 4.9%) compared to RI (median 0.2%).

Release and mobilization of Ni, Co, and Cr under dynamic redox changes in a geogenic contaminated soil: Assessing the potential risk in serpentine paddy environments

The release dynamics and mobilization of geogenic Ni, Co, and Cr in serpentine paddy soils under fluctuating redox conditions have not yet been well studied. Here we investigated the release dynamics of Cr, Co, and Ni and controlling factors (e.g., Fe, Mn, Mg, Cl−, PO43−, SO42−, and dissolved organic carbon (DOC)) in a geogenic-contaminated serpentine soil under wide range of redox potential (EH) changes. The effects of re-oxidation process have been also investigated. The soil was incubated for 28 days and EH was controlled from oxidation (+200 mV) to reduction (−200 mV) and re-oxidation (+240 mV) using a microcosm setup in duplicates. The slurry pH increased, along with decreasing EH. The average concentration of dissolved Co (17.1–23.6 μg L−1) decreased under low EH/high pH and vice versa. The average concentration of dissolved Cr decreased sharply from 624 μg L−1 to 54.4 μg L−1 with decreasing EH from +200 mV to 0 mV and the associated increase of pH from 7.8 to 8.5; then, it was constant around 24.5 μg L−1. Concentration of dissolved Ni was lower (73.5–84.6 μg L−1) under high EH at the first week of incubation; then, increased to 108.5 μg L−1 under low EH (−200 mV); thereafter, increased more at the end up to 124.5 μg L−1 at high EH (+240 mV), because of the pH decrease. A factor analysis identified that Cr and Co formed one group with Mn and Mg, while Ni was clustered together with Cl−, DOC, and SO42−. This indicates that the redox-induced release dynamic of Cr and Co was mainly governed by MnMg compounds, while the release of Ni was mainly affected by the aliphatic compounds of DOC and the redox chemistry of chlorides and sulfur in this soil. The re-oxidation increased the mobilization of Ni and Co and did not affect the release of Cr. These findings suggest that the redox-induced mobilization of geogenic Co, Ni, and Cr from soil to water in serpentine rice soils should be considered due to the high solubility and thus the associated bioavailability and potential environmental and human health risks, when such metal-enriched soils will be used for agricultural flood-dry cycle systems.

Experiments revealing the formation of refractory methylmercury pools in natural sediments and soils

Methylation and demethylation of mercury (Hg) are well recognized as processes controlling the concentrations of monomethylmercury (MeHg) in natural environments, and thus the pool of Hg available for biological uptake. In addition, studies have indicated the potential role of refractory MeHg pools (not readily available for demethylation) on the pool of MeHg in, for example, sediments and soils. These studies, however, remain scarce and often the role of refractory MeHg pools is overlooked. Here, we have conducted incubation experiments aiming to quantify refractory MeHg pools in contrasting environments. In our study, sediments (from lakes and brackish seawater sites) and soils (from forests and marshes) were incubated with isotopically enriched Hg tracers (Me201Hg and 198Hg) for up to 6 weeks. To follow the potential formation of refractory MeHg pools, %MeHg (fraction of Hg occurring as MeHg) after the first week of incubation for the added 198Hg and Me201Hg tracers, and ambient Hg was compared. The high %MeHg for the 198Hg tracer compared to the %MeHg of ambient Hg suggests a higher initial availability of added 198Hg in comparison to the ambient Hg in the sediments. For the soils, low %MeHg for the 198Hg tracer suggests low Hg methylation rates. The discrepancy observed between the sediments and soils can be explained by a higher availability of inorganic Hg in the sediments, as suggested by the Hg thermal fractional analysis conducted. The %MeHg steady state for the added Me201Hg tracer remained high (>17%) throughout the experiment, suggesting refractory pools of MeHg to be built-up in all tested sediments and soils. Together, the %MeHg for the added Hg tracers demonstrate that a significant fraction of the MeHg produced in sediments and soils is sequestered into refractory pools not readily available for demethylation. Furthermore, these results show that conditions favoring net methylation in sediments and soil could result in elevated concentrations of MeHg for a significant amount of time (months) even if the conditions favoring Hg net methylation are only temporary.

Sand characteristics do not influence hatching success of nests at the world’s largest green turtle rookery

Raine Island, located in the northern Great Barrier Reef, hosts the largest green turtle nesting aggregation in the world, but typically experiences low hatching success (20–60%, depending on the number of females visiting the island to nest). To determine whether the low hatching success of green turtle eggs at Raine Island might be explained by local sand characteristics, we investigated the physical properties of Raine Island sand and compared it to sand from other eastern coast Australian sea turtle nesting beaches that have high hatching success (>80%). We also measured the water, salt and organic material content of sand within nests at Raine Island to see whether any of these variables were correlated with the proportion of early embryo death or hatching success. The physical characteristics of Raine Island sand were similar to those of other eastern coast Australian nesting beaches, so it seems unlikely that inherent physical sand properties, water content, salt or organic matter explain the relatively low hatching success observed on Raine Island compared to other Australian green turtle nesting beaches. However, we found that nests that were inundated twice with seawater during spring high tides at the end of their first week of incubation experienced greater early development mortality and lower hatching success than did non-inundated nests, suggesting that embryos drowned during the inundation. Last, we found that hatching success declined towards the end of the nesting season, suggesting that the beach sand in the nesting areas of Raine Island changes in some way, and/or that egg quality decreases as the nesting season progresses.

Effects of Calcium Lactate on the Development of Chicken Embryos in a Shell-less Culture System up to Day Seventeen of Incubation.

This study examined the effects of calcium lactate on the development of chicken embryos in a shell-less culture system (cSLCS) up to the seventeenth day of incubation. In the presence of calcium lactate, a significant reduction in embryo viability was observed during the first week of incubation in cSLCS. On day 17 of embryo development, no significant difference was observed in the blood plasma calcium concentration or tibia bone density between cSLCS and intact control embryos, whereas the tibia length was significantly shorter in cSLCS embryos than in the intact control. These results suggest that calcium lactate supplementation in cSLCS supports bone formation in developing chicken embryos, but has adverse effects on the viability of embryos, particularly during the first week of embryo development.

Examining the Nutrient Exchange in All Incubation Periods in Chukar Partridges

Background: This study was conducted to examine the development of the embryo during incubation and the composition, amount and consumption of the egg nutrients among Chukars (Alectoris chukar). Methods: A total of 1210 eggs were carefully separated into their components (albumen, yolk, shell, amniotic-allantoic fluid and embryo) on day 0 (fresh), in the first (day 7), second (day 14) and third (day 21) weeks of incubation and on the hatching date. The moisture, crude protein, crude fat, carbohydrate, crude ash and energy level were determined in egg components. Result: The albumen, yolk, shell, fluid and embryo rates were calculated to be 53.62, 34.84, 11.53, 0.0 and 0.0% in fresh egg, 16.74, 33.49, 16.22, 31.76 and 2.06% in the first week of incubation, 15.65, 28.32, 15.58, 23.35 and 17.10% in the second week of incubation and 0.0, 23.33, 19.38, 0.0 and 57.29% in the third week of incubation, respectively. The hatching weight of the chick was 16.16 g. The nutrients of the yolk, albumen, fluid and shell proportionally varied significantly in different periods of incubation. According to the nutrient changes calculated based on the weight differences of egg components, carbohydrates were mostly used for nutrients during incubation. It was found that even though the nutrients in all the egg components were used in the different periods of incubation, egg yolk was an important source for the embryo throughout the incubation period.

Effect of high eggshell temperature during the early period of incubation on hatchability, hatch time, residual yolk, and first-week broiler performance1

During incubation, temperature is the main environmental condition affecting the hatchability and chick quality. The effect of high temperature after the first week of incubation to hatching has been widely investigated. However, very little is known during the early period of incubation. This study was conducted to investigate the effect of increased eggshell temperature ( EST ) during the first 6 embryonic d of incubation (E) on hatchability, hatch time, and first-week broiler performance. A total of 1,680 hatching eggs were divided randomly into 4 treatment groups were as follows: Control (37.8°C), High EST (38.6°C) from E0 to E3, E3 to E6, and E0 to E6. The EST was maintained at 37.8°C from E6 onward in all groups. Fertile hatchability was significantly better in eggs maintained at the control temperature (37.8°C EST through incubation) and at 38.6°C EST from E0 to E3 (High E0-E3) compared to eggs exposed to an EST of 38.6°C from E3 to E6 (HighE3-E6) and E0 to E6 (HighE0-E6) of incubation ( P < 0.05) due to decreased early embryonic mortality ( P < 0.05). The average hatch time differed among all treatments, with the earliest hatch time for HighE0-E6 followed by the HighE0-E3, HighE3-E6, and Control groups ( P < 0.01). Yolk free body mass ( YFBM ) and residual yolk sac ( RYS ) weight were not significantly affected by high EST (38.6°C) during the first 6 d of incubation. At 7 d of age, the HighE0-E3 and Control groups were found to have greater BW than the other 2 groups ( P < 0.05). No significant difference was found for feed consumption ( FC ), feed conversion ratio ( FCR ), or mortality among the treatments for 7 d ( P > 0.05). These results suggest that compared with the control condition, the exposure of eggs to 38.6°C EST from E0 to E6 or from E3 to E6 of incubation shortened the hatch time but decreased fertile hatchability and the first week BW ( P < 0.05). However, compared with the control temperature, increased EST during the first 3 d of incubation did not impact hatchability, percentage of second-grade chicks and first-week broiler performance ( P > 0.05), but chicks hatched earlier ( P < 0.05).

The Degradation of Glyphosate and Its Effect on the Microbial Community of Agro-Sod–Podzolic Soil under Short-Term Model Experiment Conditions

Under laboratory conditions, the decomposition of glyphosate with the formation of aminomethylphosphonic acid (AMPA) and its effect on the total abundance of bacteria and fungi as well as the number of copies of genes encoding the enzymes C–P lyase of α-proteobacteria (phnJ), acid and alkaline phosphatase (phoC and phoD) and Fe protein of nitrogenase (nifH) in agro-sod-podzolic soil (Epialbic Retisol) were determined. It was shown that when applying glyphosate in recommended doses (5–10 mg/kg), only 5–7% of the introduced herbicide were detected after 14 days, but when the dose was increased to 100 mg/kg, this value increased up to 23%. Decreasing the rate of the herbicide degradation was observed only during the first week of incubation and was accompanied by a decrease in the number of copies of the phoC, phoD, and nifH genes and an increase in the abundance of fungi. The obtained results indicate that glyphosate was mainly degraded by means of C–P bond breaking and the formation of phosphates, and also suggest possible inhibition of the nitrogen fixation process. It is shown that at an application dose of glyphosate of 100 mg/kg may lead to the accumulation of AMPA, the first metabolite of the herbicide degradation pathway, formed after the C–N bond break. Bioassay using wheat showed that when applying glyphosate at a dose of 100 mg/kg, an inhibition of plant development was observed: the length of the roots and the biomass of the shoots reduced by 60 and 20% compared to the control, respectively. Based on the data obtained, it was proposed to use the reduction in the content of copies of the phoC gene and the increase in the number of copies of ITS rRNA as indicators of the predominant decomposition of glyphosate through the sarcosine pathway. The decrease in the number of copies of ITS rRNA gene by 40% or more can be used as an indicator of the possibility of AMPA accumulation during glyphosate degradation.

Preliminary evaluation of application of a 3-dimensional network structure of siloxanes Dergall preparation on chick embryo development and microbiological status of eggshells

The spatial network structure of Dergall is based on substances nontoxic to humans and the environment which, when applied on solid surfaces, creates a coating that reduces bacterial cell adhesion. The bacteriostatic properties of siloxanes are based on a purely physical action mechanism which excludes development of drug-resistant microorganisms. The aims of the present study were to 1) evaluate a Dergall layer formed on the eggshell surface regarding the potential harmful effects on the chick embryo; 2) evaluate antimicrobial activity and estimate the prolongation time of Dergall's potential antimicrobial activity. Dergall at a concentration of 0.6% formed a layer on the eggshell surface. In vitro testing of the potential harmful effects of Dergall by means of a hen embryo test of the chorioallantoic membrane showed no irritation reaction at a concentration of 3% and lower. The hatchability of the groups sprayed with a Dergall water solution with a concentration of 0 to 5% was 89.1 to 93.8% for fertilized eggs (P > 0.05) but decreased to 63.7% (P < 0.05) in the group sprayed with a 6% concentration of the solution. This phenomenon was caused by embryo mortality in the first week of incubation. At the concentration of 0.6%, Dergall exhibited strong antibacterial properties against bacteria such as Staphylococcus aureus, Escherichia coli, Shigella dysenteriae, Shigella flexneri, and Salmonella typhimurium. For Streptococcus pyogenes, the highest antibacterial activity of Dergall was reported in the concentrations of 100 and 50%. For Pseudomonas aeruginosa, no antibacterial activity of Dergall was generally observed, but in vivo testing showed a strong decrease of all gram-negative bacteria growth. Moreover, a prolonged antimicrobial effect lasting until 3 D after disinfection was observed, which makes Dergall a safe and efficient disinfectant.

Early-stage macroporosity enhancement in calcium phosphate cements by inclusion of poly(N-vinylpyrrolidone) particles as a porogen

The incorporation of poly(DL-lactic-co-glycolic acid) (PLGA) particles into calcium phosphate cements (CPCs) is an effective strategy to enhance CPC macroporosity and degradation. However, bone regeneration is hindered until hydrolytic PLGA degradation starts a few weeks after implantation. Additionally, CPC and CPC/PLGA injectability and cohesion are suboptimal. In the current study, poly(N-vinylpyrrolidone) (PVP), a water-soluble polymer, was incorporated as a porogen in CPC and CPC/PLGA composites to enhance handling properties and early-stage macroporosity formation. Further, the effect of PVP molecular weight (Mw) and particle size was studied. The results showed that PVP incorporation increased both injectability and cohesion of the CPC pastes, especially with addition of high Mw PVP. Moreover, the in vitro degradation studies revealed that incorporation of PVP induced an initial mass loss during the first week of incubation. In combination with PLGA, small PVP particles induced a higher mass loss at an early stage than large PVP particles, but this effect was no longer apparent after 4 weeks of incubation. In contrast, the incorporation of low Mw PVP had a stronger effect on in vitro degradation in the long term compared to high Mw. Finally, the presence of PLGA porogens appeared to be necessary for adequate CPC degradation.

Nest Attendance Patterns in the American Alligator (Alligator mississippiensis)

The behavioral variation in alligator nest attendance has characterized the species as iconic in common lore and perplexed biologists for decades. Here, we quantify patterns in nest attendance among mothers as well as variation in such patterns throughout two nesting seasons. We employed camera traps controlled by circuit boards to capture time-lapse photographs of alligator nest areas for the duration of each nesting season. Data revealed a bimodal pattern of nest attendance over time that significantly varied across incubation days in both 2011 and 2012, and also differed between years. Nest attendance also differed among hours in the diel cycle, and this pattern was the same for both years. Nest visits were frequent immediately after the eggs were laid, and attendance behavior attenuated rapidly after the first week of incubation. Nest visitation then increased near the end of the incubation period with the largest portion of visits recorded during hatching and the maternal movement of hatchlings away ...

A preliminary investigation into the early embryo death syndrome (EEDS) at the world's largest green turtle rookery.

Raine Island hosts the largest nesting aggregation of green turtles in the world, but nest emergence success and hence recruitment of hatchlings off the beach appear to have significantly declined since the 1990s. Nests destroyed by subsequent nesting turtles, and nest failure due to flooding account for most of the nest failure, but many nests still have poor hatch success even when undisturbed and flood-free. In undisturbed, flood-free nests that experience high mortality, embryos typically die at a very early stage of development, a phenomenon we term early embryo death syndrome (EEDS). Previous research indicates that EEDS is correlated with the number of females nesting at Raine Island during a nesting season. Here, we monitor nest temperature and oxygen (PO2) and carbon dioxide (PCO2) partial pressures during the first week after nest construction to discover if they are associated with EEDS. Our investigation found that the proportion of early embryo death was greatest in two nests that experienced the highest nest temperature, lowest PO2 and highest PCO2 during the first week of incubation suggesting that these variables either by themselves or in combination may be the underlying cause of EEDS. These two nests were located adjacent to maturing nests, so the high temperature and more extreme PO2s and PCO2s are most likely to be caused by the combined metabolism of embryos in the mature nests. Although this conclusion is based on just two nests and needs to be substantiated in future studies, it would appear that the laying of new nests in the close location to mature nests could be a significant cause of hatch failure at high density nesting sea turtle rookeries around the world.

Caracterización de mortalidad embrionaria en pollos de engorde

Objetivo. El propósito de este estudio fue caracterizar la incidencia de mortalidad embrionaria (ME) en huevos de estirpes Ross 308 en una empresa de Santander, Colombia. Materiales y métodos. Se realizó un estudio de cohorte prospectivo en el cual se siguieron durante la incubación, por medio de ovoscopía y embriodiagnóstico, 4 grupos de huevos provenientes de reproductoras de 4 edades diferentes. Se reporta el porcentaje de infertilidad, de malformaciones, malposición, huevos fisurados y contaminados. Resultados. La ME general alcanzó 16.08% IC95%(14.69; 17.60) y fue diferente entre los grupos de edad (p&lt;0.001); esta fue mayor para los huevos de reproductoras de 64 semanas con 27.66% IC95% (23.92; 31.99) y menor para las de 47 semanas con 8.84% IC95% (6.97; 11.22). En la primera semana de incubación murió el 57.53% de los embriones y se presentó el pico de muerte entre los días 1 y 3; la segunda semana murió el 38.42%, con un máximo de muertes entre el día 19 y 21. Conclusiones. Este estudio, es el primero de su naturaleza para la zona y la estirpe y permitió confirmar el comportamiento bifásico de la ME aunque existen variaciones en los picos de mortalidad atribuidas posiblemente a las diferencias de las condiciones de producción propias de las empresas.

Slowing the Mold Growth on Stored Corn: The Effects of Vinegar, Baker’s Yeast, and Yogurt on Corn Weight Loss

There are many methods for preserving grain, most of them chemical. The application of chemical preservatives, such as strong acids or antifungal chemicals, has negative effects on farm storage facilities, animals, and humans. Biologically and environmentally friendly inhibitors can reduce the growth of harmful fungi and molds while also having nutritional benefits. In this study, three substances were used to study mold growth on corn kernels. Vinegar, baker’s yeast, and yogurt were applied to corn. Tap water was used as a control. Prior to adding these three substances the corn was steeped to reach a 30% moisture level and stored in Ziploc- plastic bags at room temperature (approximately 25C). Bags were weighed once a week and weight losses were recorded. Weight loss after four weeks was highest in the water treatment and lowest in the baker’s yeast treatment. Both the yogurt and baker’s yeast treatment were associated with more weight loss during the first week than the other two treatments, weight loss being a measure of mold growth. However, the baker’s yeast and yogurt treatments were associated with the least amount of weight loss during the last two weeks of incubation. Vinegar was very successful at preventing weight loss during the first week of incubation but the corn lost weight at a rate similar to that of the control during the following three weeks. In conclusion, biological treatments were as successful as chemical treatments in slowing down mold growth in corn after four weeks of incubation.

Is biochar-manure co-compost a better solution for soil health improvement and N2O emissions mitigation?

Land application of compost has been a promising remediation strategy for soil health and environmental quality, but substantial emissions of greenhouse gases, especially N2O, need to be controlled during making and using compost of high N-load wastes, such as chicken manure. Biochar as a bulking agent for composting has been proposed as a novel approach to solve this issue, due to large surface area and porosity, and thus high ion exchange and adsorption capacity. Here, we compared the impacts of biochar-chicken manure co-compost (BM) and chicken manure compost (M) on soil biological properties and processes in a 120-d microcosm experiment at the soil moisture of 60% water-filled pore space. Our results showed that BM and M addition significantly enhanced soil total C and N, inorganic and KCl-extractable organic N, microbial biomass C and N, cellulase enzyme activity, abundance of N2O-producing bacteria and fungi, and gas emissions of N2O and CO2. However, compared to the M treatment, BM significantly reduced soil CO2 and N2O emissions by 35% and 27%, respectively, over the experimental period. The 15N-N2O site preference, i.e., difference between 15N-N2O in the center position (δ15Nα) and the end position (δ15Nβ), was ∼17‰ for M and ∼26‰ for BM during the first week of incubation, suggesting that BM suppressed N2O from bacterial denitrification and/or nitrifier denitrification. This inference was well aligned with the observation that soil glucosaminidase activity and nirK gene abundance were lower in BM than M treatment. Further, soil peroxidase activity was greater in BM than M treatment, implying soil organic C was more stable in BM treatment. Our data demonstrated that the biochar-chicken manure co-compost could substantially reduce soil N2O emissions compared to chicken manure compost, via controls on soil organic C stabilization and the activities of microbial functional groups, especially bacterial denitrifiers.

Short-term biochar application induced variations in C and N mineralization in a compost-amended tropical soil.

To mitigate food shortage due to global warming, developing sustainable management practices to stabilize soil organic matter (SOM) and sequester more carbon (C) in the cultivated soils is necessary, particularly in subtropical and tropical areas. A short-term (56days) incubation experiment was conducted to evaluate the influences of rice husk biochar (RHB) and manure compost (MC) application on C mineralization and nitrogen (N) immobilization in a sandy loam soil. The RHB was separately incorporated into the soil at application rates of 2 and 4% (w/w) either with or without 1% (w/w) compost. Our results displayed that macroaggregates (≥2mm) were obviously increased by 11% in soil amended with RHB+MC at the end of incubation. In addition, the experimental results presented that the C mineralization of the soil rapidly increased during the first week of incubation. However, the co-application of compost with biochar (RHB+MC) revealed that CO2 emission was significantly decreased by 13-20% compared to the soil with only MC. In addition, the mineralized N in the soil was lower in RHB+MC-amended soil simultaneously than only MC-amended soil, indicating that biochar addition induced N immobilization. The physical protection of compost by its occlusion into aggregates or adsorption on surface of RHB as proved by the micromorphological observation was the main reason for lower C and N mineralization in soil amended with RHB+MC. Overall results revealed that RHB+MC treatment can decrease the decomposition of compost and sequester more C in the tropical agricultural soils.

Metatranscriptomic Analysis Reveals Unexpectedly Diverse Microbial Metabolism in a Biogeochemical Hot Spot in an Alluvial Aquifer.

Organic matter deposits in alluvial aquifers have been shown to result in the formation of naturally reduced zones (NRZs), which can modulate aquifer redox status and influence the speciation and mobility of metals, affecting groundwater geochemistry. In this study, we sought to better understand how natural organic matter fuels microbial communities within anoxic biogeochemical hot spots (NRZs) in a shallow alluvial aquifer at the Rifle (CO) site. We conducted a 20-day microcosm experiment in which NRZ sediments, which were enriched in buried woody plant material, served as the sole source of electron donors and microorganisms. The microcosms were constructed and incubated under anaerobic conditions in serum bottles with an initial N2 headspace and were sampled every 5 days for metagenome and metatranscriptome profiles in combination with biogeochemical measurements. Biogeochemical data indicated that the decomposition of native organic matter occurred in different phases, beginning with mineralization of dissolved organic matter (DOM) to CO2 during the first week of incubation, followed by a pulse of acetogenesis that dominated carbon flux after 2 weeks. A pulse of methanogenesis co-occurred with acetogenesis, but only accounted for a small fraction of carbon flux. The depletion of DOM over time was strongly correlated with increases in expression of many genes associated with heterotrophy (e.g., amino acid, fatty acid, and carbohydrate metabolism) belonging to a Hydrogenophaga strain that accounted for a relatively large percentage (~8%) of the metatranscriptome. This Hydrogenophaga strain also expressed genes indicative of chemolithoautotrophy, including CO2 fixation, H2 oxidation, S-compound oxidation, and denitrification. The pulse of acetogenesis appears to have been collectively catalyzed by a number of different organisms and metabolisms, most prominently pyruvate:ferredoxin oxidoreductase. Unexpected genes were identified among the most highly expressed (>98th percentile) transcripts, including acetone carboxylase and cell-wall-associated hydrolases with unknown substrates (numerous lesser expressed cell-wall-associated hydrolases targeted peptidoglycan). Many of the most highly expressed hydrolases belonged to a Ca. Bathyarchaeota strain and may have been associated with recycling of bacterial biomass. Overall, these results highlight the complex nature of organic matter transformation in NRZs and the microbial metabolic pathways that interact to mediate redox status and elemental cycling.

Formation of Carbonate Nanoglobules by a Mixed Natural Culture under Hypersaline Conditions

The present study demonstrated formation of Ca and P rich nanoglobules by a mixed natural halophilic population enriched from hypersaline lake sediments in laboratory culture experiments. Nanoglobules consisting of complex mixture of Ca, P, O, and C with minor amount of Mg occurred in the external envelop of bacterial cell in the first week of incubation at various Mg+2/Ca+2 ratios and salinity at 30 °C. Unlike the control experiments (e.g., non-viable cells and without cells), later aggregation and transformation of nanoglobules caused the precipitation of calcium and/or magnesium carbonates in variable amount depending on the Mg+2/Ca+2 ratios of the medium after 37 days of incubation. By showing the nucleation of carbonates on bacterial nanoglobules closely associated with the cell surfaces of mixed natural population this study emphasis that formation of nanoglobules may not be specific to a microbial strain or to activity of a particular microbial group. Formation of carbonate nanoglobules under various conditions (e.g., Mg+2/Ca+2 ratios, salinity) with the same halophilic culture suggest that the although metabolic activity of bacteria have an influence on formation of nanoglobules the mineralogy of nanoglobules may be controlled by the physicochemical conditions of the precipitation solution and the rate of mineral precipitation.