Investigating the inhibitory mechanism of methanogenesis during composting under the combined influence of amoxicillin and copper pollution.

This study investigated the effects of different levels of combined amoxicillin and copper (Cu) pollution on the methanogenesis of microbial communities during aerobic composting of dairy manure. Three groups were established: the control group (CK), a low-level combined pollution group (L), and a high-level combined pollution group (H). As the level of pollution increased, carbohydrate metabolism decreased during the thermophilic phase of composting, while signal translation increased. Compared with the initial phase, functional genes related to the acetoclastic pathway decreased significantly in abundance during the thermophilic phase, and cdh had the lowest relative abundance among acetoclastic pathway with a decrease of 81.52%, 81.88%, and 84.73% in groups CK, L, and H, respectively. The cumulative methane emissions in group H decreased by 31.56% and 9.23%, respectively, compared with those from groups CK and L. These results contribute to understanding the effects of combined amoxicillin and Cu pollution on methane emissions during composting.

National Greenhouse Gas Emission Reduction Potential from Adopting Anaerobic Digestion on Large-Scale Dairy Farms in the United States.

Waste-to-energy systems can provide a functional demonstration of the economic and environmental benefits of circularity, innovation, and reimagining existing systems. This study offers a robust quantification of the greenhouse gas (GHG) emission reduction potential of the adoption of anaerobic digestion (AD) technology on applicable large-scale dairy farms in the contiguous United States. GHG reduction estimates were developed through a robust life cycle modeling framework paired with sensitivity and uncertainty analyses. Twenty dairy configurations were modeled to capture important differences in housing and manure management practices, applicable AD technologies, regional climates, storage cleanout schedules, and methods of land application. Monte Carlo results for the 90% confidence interval illustrate the potential for AD adoption to reduce GHG emissions from the large-scale dairy industry by 2.45-3.52 MMT of CO2-eq per year considering biogas use only in renewable natural gas programs and as much as 4.53-6.46 MMT of CO2-eq per year with combined heat and power as an additional biogas use case. At the farm level, AD technology may reduce GHG emissions from manure management systems by 58.1-79.8% depending on the region. Discussion focuses on regional differences in GHG emissions from manure management strategies and the challenges and opportunities surrounding AD adoption.

Micro-positive pressure significantly decreases greenhouse gas emissions by regulating archaeal community during industrial-scale dairy manure composting.

In this study, the effects of micro-positive pressure formed by covering with a semipermeable membrane in the heating phase of dairy manure composting on greenhouse gas emissions and the mechanism of reducing methane emissions by the archaeal community were investigated. A large-scale experiment was conducted with semipermeable membrane-covered composting (SMC), forced aeration composting (FAC), and traditional static composting (TSC) groups. The results showed that the oxygen concentration and methanogen abundance were key factors in regulating methane emissions. In the heating phase of SMC, the micro-positive pressure could enhance the O2 utilization rate and heating rate, resulting in Methanobrevibacter and Methanobacterium greatly decreasing, and the abundance of mcrA decreased by 90.03%, while that of pmoA did not increase. Compared with FAC and TSC, the cumulative methane emissions in SMC decreased by 51.75% and 96.04%, respectively. Therefore, the micro-positive pressure could effectively reduce greenhouse gas emissions by inhibiting the growth of methanogens.

Determining the prevalence of Escherichia coli, Salmonella, and shiga toxin-producing Escherichia coli in manure of dairy lagoons.

AIM: The aim of this study was to determine the prevalence of microbial pathogens in manure of dairy lagoons in California. METHODS AND RESULTS: To determine pathogens in dairy manure stored in anaerobic lagoons of dairy farm, an extensive field study was conducted across California to sample manure from 20 dairy farms. Samples were analyzed to determine the prevalence of indicator Escherichia coli, Shiga toxin producing E. coli (STEC), Salmonella, and E. coli O157: H7. To test the E. coli, STEC, and Salmonella, we used agar culture-based method followed by polymerase chain reaction (PCR) method. In addition, a real- time PCR based method was used to determine the presence of E coli O157: H7. Study demonstrated that the prevalence of Salmonella in manure sample is lower than E. coli. The presence of Salmonella was found in 2.26% of the samples, and both the culture-based and PCR methods yielded comparable outcomes in detecting Salmonella. Moreover, ∼11.30% of the total samples out of the 177 were identified as positive for STEC by qPCR. CONCLUSION: These findings demonstrate that indicator E. coli are abundantly present in anaerobic lagoons. However, the presence of STEC, and Salmonella is substantially low.

Quantitative microbial risk assessment for ingestion of antibiotic resistance genes from private wells contaminated by human and livestock fecal sources.

We used quantitative microbial risk assessment to estimate ingestion risk for intI1, erm(B), sul1, tet(A), tet(W), and tet(X) in private wells contaminated by human and/or livestock feces. Genes were quantified with five human-specific and six bovine-specific microbial source-tracking (MST) markers in 138 well-water samples from a rural Wisconsin county. Daily ingestion risk (probability of swallowing ≥1 gene) was based on daily water consumption and a Poisson exposure model. Calculations were stratified by MST source and soil depth over the aquifer where wells were drilled. Relative ingestion risk was estimated using wells with no MST detections and >6.1 m soil depth as a referent category. Daily ingestion risk varied from 0 to 8.8 × 10-1 by gene and fecal source (i.e., human or bovine). The estimated number of residents ingesting target genes from private wells varied from 910 (tet(A)) to 1,500 (intI1 and tet(X)) per day out of 12,000 total. Relative risk of tet(A) ingestion was significantly higher in wells with MST markers detected, including wells with ≤6.1 m soil depth contaminated by bovine markers (2.2 [90% CI: 1.1-4.7]), wells with >6.1 m soil depth contaminated by bovine markers (1.8 [1.002-3.9]), and wells with ≤6.1 m soil depth contaminated by bovine and human markers simultaneously (3.1 [1.7-6.5]). Antibiotic resistance genes (ARGs) were not necessarily present in viable microorganisms, and ingestion is not directly associated with infection. However, results illustrate relative contributions of human and livestock fecal sources to ARG exposure and highlight rural groundwater as a significant point of exposure.IMPORTANCEAntibiotic resistance is a global public health challenge with well-known environmental dimensions, but quantitative analyses of the roles played by various natural environments in transmission of antibiotic resistance are lacking, particularly for drinking water. This study assesses risk of ingestion for several antibiotic resistance genes (ARGs) and the class 1 integron gene (intI1) in drinking water from private wells in a rural area of northeast Wisconsin, United States. Results allow comparison of drinking water as an exposure route for antibiotic resistance relative to other routes like food and recreational water. They also enable a comparison of the importance of human versus livestock fecal sources in the study area. Our study demonstrates the previously unrecognized importance of untreated rural drinking water as an exposure route for antibiotic resistance and identifies bovine fecal material as an important exposure factor in the study setting.

Microbial diversity in dairy manure environment under liquid-solid separation systems.

In dairy manure, a wide array of microorganisms, including many pathogens, survive and grow under suitable conditions. This microbial community offers a tremendous opportunity for studying animal health, the transport of microbes into the soil, air, and water, and consequential impacts on public health. The aim of this study was to assess the impacts of manure management practices on the microbial community of manure. The key novelty of this work is to identify the impacts of various stages of manure management on microbes living in dairy manure. In general, the majority of dairy farms in California use a flush system to manage dairy manure, which involves liquid-solid separations. To separate liquid and solid in manure, Multi-stage Alternate Dairy Effluent Management Systems (ADEMS) that use mechanical separation systems (MSS) or weeping wall separation systems (WWSS) are used. Thus, this study was conducted to understand how these manure management systems affect the microbial community. We studied the microbial communities in the WWSS and MSS separation systems, as well as in the four stages of the ADEMS. The 16S rRNA gene from the extracted genomic DNA of dairy manure was amplified using the NovoSeq Illumina next-generation sequencing platform. The sequencing data were used to perform the analysis of similarity (ANOSIM) and multi-response permutation procedure (MRRP) statistical tests, and the results showed that microbial communities among WWSS and MSS were significantly different (p < 0.05). These findings have significant practical implications for the design and implementation of manure management practices in dairy farms.

Biochar and Dairy Manure Amendment Effects on Cynodon dactylon Performance and Soil Properties.

Studies have determined the separate effects of biochar (BC) and manure application on forage species and soil, but few examined the effects of BCs made from different feedstock applied along with dairy manure. We compared the effect of wood- and manure-derived feedstock BC as well as dairy manure amendment application on Cynodon dactylon performance and soil properties in sandy loam and clay loam soils in a greenhouse pot study. Plant samples were assayed for herbage and root dry weight as well as herbage and root N and C percent and yield. Soil samples were assayed for macronutrients, micronutrients, metals, pH and conductivity. Data analyses involved variance analysis and Tukey's tests using R in RStudio (the IDE). In general, C. dactylon yields or mineral content were not affected by either manure or BC. However, an increase in the total herbage dry weight (30%) and in herbage N% (55%) was observed for clay loam and sandy loam soil, respectively, due to manure amendment application. There were no alterations in clay loam NO3-N and P due to any treatment; however, in sandy loam, these nutrients were not altered only when wood BC was applied. In sandy loam soil, NO3-N and P increased when manure BC along with dairy manure and when manure BC alone were applied, respectively. Thus, wood BC application should be considered to avoid these nutrient buildups when dairy manure is used as a soil amendment. This research shows a neutral (BC) or positive (dairy manure amendment) impact on C. dactylon performance. BC incorporation increases soil total C, showing potential for C sequestration. Long-term field trials could corroborate plant performance and soil parameters.

Hydrochar drives reduction in bioavailability of heavy metals during composting via promoting humification and microbial community evolution.

This study presented the effects of hydrochar on humification, heavy metals (HMs) bioavailability and bacterial community succession during composting. Results indicated that hydrochar addition led to elevated composting temperature, 7.3% increase in humic acid (HA), and 52.9% increase in ratio of humic acid to fulvic acid. The diethylene triamine pentacetic acid extractable Zn, Cu, Pb, and Ni were reduced by 19.2%, 36.3%, 37.8%, and 27.1%, respectively, in hydrochar-involved composting system. Furthermore, main mechanisms driving the reduced HMs bioavailability by hydrochar addition were revealed. The addition of hydrochar significantly modified the microbial community structure. Correlation analysis and microbial analysis demonstrated that relative abundance of bacterial groups connected with humification and HMs passivation were increased. Consequently, the HA formation was promoted and the HMs bioavailability were reduced through bacterial bioremediation and HA complexation. This study demonstrates the addition of hydrochar as a promising strategy to mitigate the HMs bioavailability during composting.

Anaerobic digestion of liquid dairy manure pretreated by the microwave-enhanced advanced oxidation process.

The microwave-enhanced advanced oxidation process (MW-AOP) was utilized for the treatment of liquid dairy manure, prior to anaerobic digestion (AD). A significant amount of soluble chemical oxygen demand (SCOD) was formed in the treated solution, but there was no or little increase in volatile fatty acid (VFA). In this study, up-flow anaerobic sludge blanket (UASB) reactors were used in both the conventional AD system and as the methane phase reactor in a two-phase anaerobic digestion (TPAD) system. Both AD systems were capable of operating at very short hydraulic retention times (HRTs) to as low as about 3 days, and very high methane production rates were achieved. However, much higher methane production was obtained in the TPAD system. The phase separation of the acidogenesis and the methanogenesis in the TPAD system not only increased methane production but also maintained reactor stability throughout the experimental period. Thus, the combination of MW-AOP treatment and TPAD appears to be an effective means of energy recovery from dairy manure.

Partial wet oxidation of dairy manure as a pretreatment process to produce acetic acid 'a Source Growth of Methanogens'.

Wet oxidation can be an effective process for the pretreatment of complex biomass such as lignocellulose. However, studies on the use of wet oxidation for treating solid waste such as dairy manure are limited. The use of partial wet oxidation to convert dairy manure into low molecular weight carboxylic acids as final products were investigated. This work focuses on the performance of the sub-critical wet oxidation treatment of dairy cattle manure as a conversion/pretreatment process to release matter from the lignocellulosic fraction rather than a destructive process. The operating conditions were controlled at the short residence time and optimal temperature in the presence of oxygen under a pressure of 120 psi. The thermal hydrolysis under wet oxidation significantly affected conversion manure slurry into organic acids. The concentration of acetic acid reached 1778 mg L-1, achieved at 190°C (60 minutes reaction time) as the reaction temperature increased within the range of 150°C-200°C, total organic carbon was reduced and monomers in the process liquids decreased. On the other hand, soluble COD in process liquids increased with an increment in reaction temperature. The results provide insights into technical options to pretreat dairy manure to improve biochemical conversion yield.

Optimization of Simultaneous Nutrients and Chemical Oxygen Demand Removal from Anaerobically Digested Liquid Dairy Manure in a Two-Step Fed Sequencing Batch Reactor System Using Taguchi Method and Grey Relational Analysis.

The technological development for efficient nutrient removal from liquid dairy manure is critical to a sustainable dairy industry. A nutrient removal process using a two-step fed sequencing batch reactor (SBR) system was developed in this study to achieve the applicability of simultaneous removal of phosphorus, nitrogen, and chemical oxygen demand from anaerobically digested liquid dairy manure (ADLDM). Three operating parameters, namely anaerobic time:aerobic time (min), anaerobic DO:aerobic DO (mg L-1), and hydraulic retention time (days), were systematically investigated and optimized using the Taguchi method and grey relational analysis for maximum removal efficiencies of total phosphorus (TP), ortho-phosphate (OP), ammonia-nitrogen (NH3-N), total nitrogen (TN), and chemical oxygen demand (COD) simultaneously. The results demonstrated that the optimal mean removal efficiencies of 91.21%, 92.63%, 91.82%, 88.61%, and 90.21% were achieved for TP, OP, NH3-N, TN, and COD at operating conditions, i.e., anaerobic:aerobic time of 90:90 min, anaerobic DO:aerobic DO of 0.4:2.4 mg L-1, and HRT of 3 days. Based on analysis of variance, the percentage contributions of these operating parameters towards the mean removal efficiencies of TP and COD were ranked in the order of anaerobic DO:aerobic DO > HRT > anaerobic time:aerobic time, while HRT was the most influential parameter for the mean removal efficiencies of OP, NH3-N, and TN followed by anaerobic time:aerobic time and anaerobic DO:aerobic DO. The optimal conditions obtained in this study are beneficial to the development of pilot and full-scale systems for simultaneous biological removal of phosphorus, nitrogen, and COD from ADLDM.

Physico-chemical assessment of on-farm bioconversion of organic waste in dairy farms in context to sustainability and circular bioeconomy.

On a milk-producing dairy farm, milk production is correlated with manure production and the number of cattle, and manure is widely used as a soil fertilizer. However, excessive dairy manure production is linked with greenhouse gas emissions and water quality issues. On-farm planning of manure storage and application to enhance soil nutrients are essential in a circular economy to reduce environmental impact, where manure is not landfilled and incinerated. Instead, it creates a nutrient resource for crops and soil. Dairy manure, which is rich in nutrients, is a valuable fertilizer that contains many nutrients such as nitrogen (N), organic matter (OM), phosphorous (P), Potassium (K) and micronutrients. In this work, a pilot field research was conducted between 2016 and 2018 in various parts of California, USA (San Joaquin Valley, Sacramento Valley, Shasta Cascade, and the North Coast of California) to assess physio-chemical characteristics of solid fractions of dairy manure among various dairy farms. A total of 156 samples were collected from the gut (n = 107) and toe (n = 49) of the manure piles across California for determining total solid (TS), volatile solid (VS), temperature, moisture content and carbon-nitrogen ratio (C: N). Here, using the observations of field study and analysis, we show that C: N, OM and MC of solid fractions of dairy manure vary significantly among dairy farms. The average C: N ratio of manure (26-32) among various regions was close to an ideal C: N value of 24:1 for soil microbes to stimulate nutrient release to crops. Manure pH ranged between 7.0 and 8.0, which was close to an optimal pH range for common crops (6.0-8.0). Moreover, considering less cost and surplus availability, manure will likely continue providing a cost-effective organic fertilizer resource compared to commercial chemical fertilizers.

Effect comparisons of different conditioners and microbial agents on the degradation of estrogens during dairy manure composting.

To investigate the degradation efficiency of conditioners and commercial microbial agents on estrogens (E1, 17α-E2, 17ß-E2, E3, EE2, and DES) in the composting process of dairy manure, seven different treatments (RHB-BF, OSP-BF, SD-BF, MR-BF, MR-FS, MR-EM, and MR-CK) under forced ventilation conditions were composted and monitored regularly for 30 days. The results indicated that the removal rates of estrogens in seven treatments ranged from 95.35% to 99.63%, meanwhile the degradation effect of the composting process on 17ß-Estradiol equivalent (EEQ) was evaluated, and the removal rate of ΣEEQ ranged from 96.42% to 99.72%. With the combined addition of rice husk biochar (RHB) or oyster shell powder (OSP) and bio-bacterial fertilizer starter cultures (BF), namely RHB-BF and OSP-BF obviously promoted the rapid degradation of estrogens. 17ß-E2 was completely degraded on the fifth day of composting in OSP-BF. Microbial agents have some promotional effect and enhances the microbial degradation of synthetic estrogen (EE2, DES). According to the results of RDA, pH and EC were the main environmental factors affecting on the composition and succession of estrogen-related degrading bacteria in composting system. As predominant estrogens-degrading genera, Acinetobacter, Bacillus, and Pseudomonas effected obviously on the change of estrogens contents. The research results provide a practical reference for effective composting of dairy manure to enhancing estrogens removal and decreasing ecological risk.

Response surface optimization of chemical coagulation for solid-liquid separation of dairy manure slurry through Box-Behnken design with desirability function.

Discharging livestock manure slurry without proper treatment causes various environmental and sociological problems. Chemical coagulation is a widely used and easily applicable method for treating such wastewater. However, the technique requires optimization to enhance coagulation efficiency while minimizing chemical usage. In this study, we propose an efficient, low-cost, and environmentally safe chemical coagulation method for solid-liquid separation of dairy manure slurry. Experiments were conducted in laboratory jar tests using dairy manure slurry to investigate the impact of coagulants, specifically polyaluminum chloride (PAC) and cationic polyacrylamide (CPAM), as well as pH, on the process of solid-liquid separation. Preliminary ranges of PAC, CPAM, and pH were estimated through single-factor experiments. Coagulation optimization and modeling were performed using the response surface methodology (RSM) with the Box-Behnken design (BBD), wherein the desired goal of each parameter was set to maximize solid-liquid separation efficiency while reducing chemical dosage to maintain residual aluminum (Al) concentrations below water quality standards. Numerical optimization predicted that the optimal dosages were 75 mg/L of PAC and 35 mg/L of CPAM at pH 7. Under these conditions, removal efficiencies of 99% for turbidity and 97% for chemical oxygen demand (COD) were achieved, with a minimal residual Al concentration of 0.045 mg/L. Positive zeta potential values in the treated water confirmed complete separation of negatively charged solids in the dairy manure slurry. The response values predicted by BBD aligned with the experimental results, and the analysis of variance (ANOVA) demonstrated the predictability and accuracy of the response models. Consequently, this study highlights the practical application of RSM with BBD in optimizing chemical coagulation using PAC and CPAM to achieve efficient solid-liquid separation in livestock wastewater while maintaining low residual Al concentrations.

Abiotic and Biotic Drivers of Soil Fungal Communities in Response to Dairy Manure Amendment.

Modern agriculture often relies on large inputs of synthetic fertilizers to maximize crop yield potential, yet their intensive use has led to nutrient losses and impaired soil health. Alternatively, manure amendments provide plant available nutrients, build organic carbon, and enhance soil health. However, we lack a clear understanding of how consistently manure impacts fungal communities, the mechanisms via which manure impacts soil fungi, and the fate of manure-borne fungi in soils. We assembled soil microcosms using five soils to investigate how manure amendments impact fungal communities over a 60-day incubation. Further, we used autoclaving treatments of soils and manure to determine if observed changes in soil fungal communities were due to abiotic or biotic properties, and if indigenous soil communities constrained colonization of manure-borne fungi. We found that manure amended soil fungal communities diverged from nonamended communities over time, often in concert with a reduction in diversity. Fungal communities responded to live and autoclaved manure in a similar manner, suggesting that abiotic forces are primarily responsible for the observed dynamics. Finally, manure-borne fungi declined quickly in both live and autoclaved soil, indicating that the soil environment is unsuitable for their survival. IMPORTANCE Manure amendments in agricultural systems can impact soil microbial communities via supplying growth substrates for indigenous microbes or by introducing manure-borne taxa. This study explores the consistency of these impacts on soil fungal communities and the relative importance of abiotic and biotic drivers across distinct soils. Different fungal taxa responded to manure among distinct soils, and shifts in soil fungal communities were driven largely by abiotic factors, rather than introduced microbes. This work demonstrates that manure may have inconsistent impacts on indigenous soil fungi, and that abiotic properties of soils render them largely resistant to invasion by manure-borne fungi.

Influence of Dairy Manure as Inoculum Source on Anaerobic Digestion of Swine Manure.

Inoculation is a widely used method to improve the efficiency of anaerobic digestion (AD) with a high organic load. This study was conducted to prove the potential of dairy manure as an inoculum source for AD of swine manure. Furthermore, an appropriate inoculum-to-substrate (I/S) ratio was determined to improve methane yield and reduce the required time of AD. We carried out 176 days of anaerobic digestion for five different I/S ratios (3, 1, and 0.3 on a volatile solid basis, dairy manure alone, and swine manure alone) of manure, using solid container submerged lab-scale reactors in mesophilic conditions. As a result, solid-state swine manure inoculated with dairy manure could be digested without inhibition caused by ammonia and volatile fatty acid accumulation. The highest methane yield potential was observed in I/S ratios 1 and 0.3, as 133 and 145 mL CH4·g-1-VS, respectively. The lag phase of swine manure alone was more extended, 41 to 47 days, than other treatments containing dairy manure, directly related to tardy startup. These results revealed that dairy manure can be used as an inoculum source for AD of swine manure. The proper I/S ratios leading to successful AD of swine manure were 1 and 0.3.

Nitrogen transformation processes catalyzed by manure microbiomes in earthen pit and concrete storages on commercial dairy farms.

Storing manure is an essential aspect of nutrient management on dairy farms. It presents the opportunity to use manure efficiently as a fertilizer in crop and pasture production. Typically, the manure storages are constructed as earthen, concrete, or steel-based structures. However, storing manure can potentially emit aerial pollutants to the atmosphere, including nitrogen and greenhouse gases, through microbial and physicochemical processes. We have characterized the composition of the microbiome in two manure storage structures, a clay-lined earthen pit and an aboveground concrete storage tank, on commercial dairy farms, to discern the nitrogen transformation processes, and thereby, inform the development of mitigation practices to preserve the value of manure. First, we analyzed the 16S rRNA-V4 amplicons generated from manure samples collected from several locations and depths (0.3, 1.2, and 2.1-2.75 m below the surface) of the storages, identifying a set of Amplicon Sequence Variant (ASVs) and quantifying their abundances. Then, we inferred the respective metabolic capabilities. These results showed that the manure microbiome composition was more complex and exhibited more location-to-location variation in the earthen pit than in the concrete tank. Further, the inlet and a location with hard surface crust in the earthen pit had unique consortia. The microbiomes in both storages had the potential to generate ammonia but lacked the organisms for oxidizing it to gaseous compounds. However, the microbial conversion of nitrate to gaseous N2, NO, and N2O via denitrification and to stable ammonia via dissimilatory nitrite reduction seemed possible; minor quantities of nitrate was present in manure, potentially originating from oxidative processes occurring on the barn floor. The nitrate-transformation linked ASVs were more prevalent at the near-surface locations and all depths of the inlet. Anammox bacteria and archaeal or bacterial autotrophic nitrifiers were not detected in either storage. Hydrogenotrophic Methanocorpusculum species were the primary methanogens or methane producers, exhibiting higher abundance in the earthen pit. These findings suggested that microbial activities were not the main drivers for nitrogen loss from manure storage, and commonly reported losses are associated with the physicochemical processes. Finally, the microbiomes of stored manure had the potential to emit greenhouse gases such as NO, N2O, and methane.

Whole genome characterization of thermophilic Campylobacter species isolated from dairy manure in small specialty crop farms of Northeast Ohio.

Introduction: With more public interest in consuming locally grown produce, small specialty crop farms (SSCF) are a viable and growing segment of the food production chain in the United States. Methods: The goal of this study was to investigate the genomic diversity of Campylobacter isolated from dairy manure (n = 69) collected from 10 SSCF in Northeast Ohio between 2018 and 2020. Results: A total of 56 C. jejuni and 13 C. coli isolates were sequenced. Multi-locus sequence typing (MLST) identified 22 sequence types (STs), with ST-922 (18%) and ST-61 (13%) predominant in C. jejuni and ST-829 (62%) and ST-1068 (38%) predominant in C. coli. Interestingly, isolates with similar genomic and gene contents were detected within and between SSCF over time, suggesting that Campylobacter could be transmitted between farms and may persist in a given SSCF over time. Virulence-associated genes (n = 35) involved in the uptake and utilization of potassium and organic compounds (succinate, gluconate, oxoglutarate, and malate) were detected only in the C. jejuni isolates, while 45 genes associated with increased resistance to environmental stresses (capsule production, cell envelope integrity, and iron uptake) were detected only in the C. coli isolates. Campylobacter coli isolates were also sub-divided into two distinct clusters based on the presence of unique prophages (n = 21) or IncQ conjugative plasmid/type-IV secretion system genes (n = 15). Campylobacter coli isolates harbored genes associated with resistance to streptomycin (aadE-Cc; 54%) and quinolone (gyrA-T86I; 77%), while C. jejuni had resistance genes for kanamycin (aph3'-IIIa; 20%). Both species harbored resistance genes associated with ß-lactam (especially, blaOXA-193; up to 100%) and tetracycline (tetO; up to 59%). Discussion/Conclusion: Our study demonstrated that Campylobacter genome plasticity associated with conjugative transfer might provide resistance to certain antimicrobials and viral infections via the acquisition of protein-encoding genes involved in mechanisms such as ribosomal protection and capsule modification.

Reduction and valorization of dairy manure by organic chelating acid-assisted hydrothermal process: Dewatering performance, energy recovery, and effluent toxicity.

Livestock manure with high moisture content is a challenge for management and further disposal. In this study, the organic chelating acid(EDTA)-assisted hydrothermal (EAHT) process was used to achieve dewatering, dry mass minimization, and volume reduction of dairy manure (DM). The hydrophobic modification of DM resulted in a 55% reduction in dry mass, and the specific resistance to filtration (SRF) showed a shift in dewatering performance from unfilterable to highly filterable. An investigation of the reaction mechanisms suggests that proteins and polysaccharides were released from the damaged extracellular polymeric substances (EPS) of the DM into effluent. The surface functional groups of the hydrochar were changed from hydrophilic to hydrophobic, which promotes the transformation of bound water to free water in the DM with enhanced dewatering performance. The obtained hydrochar at 17.5 mg/g EDTA dosage exhibited the highest calorific value (HHVdaf = 29.25 MJ/kg). The HHVdry of samples have little difference and approach that of anthracite coal (19.2-21.1 MJ/kg)After EAHT, the combustion safety of the hydrochar was improved, which is highly significant for its use as biofuel. The by-product effluent showed lower biological toxicity after EAHT than after HT. The findings of this study demonstrated that EAHT can be efficient in achieving DM reduction and energy recovery, which provides widespread agricultural and environmental application prospects.

Compaction effects on greenhouse gas and ammonia emissions from solid dairy manure.

Waste management practices of solid dairy manures were evaluated under controlled conditions to study gas transport and emission inside manure piles. Three applied stresses and three moisture contents were tested to represent manure conditions managed at various pile depths. A Fourier-transform infrared spectroscopy monitor measured concentrations of greenhouses gases [methane, carbon dioxide, and nitrous oxide] and ammonia as part of gas flux rate calculations. Results showed that carbon dioxide dominated the greenhouse gas emissions under all test conditions. Gas transfer, primarily diffusion, was facilitated by manure with high mechanical strength and high permeability. Gas emission rates reduced dramatically when moisture content increased in manure with high water holding capacity, while compaction treatments did not as strongly affect the gas emission rates. Results provide fundamental insights into management strategies for reducing gas emissions from solid dairy manure.