Additional Nitrogen Source Research Articles

Nitrogen fertilizers activate siderophore production by the common scab causative agent Streptomyces scabiei.

Streptomyces scabiei is the causative agents of common scab on root and tuber crops. Life in the soil imposes intense competition between soil-dwelling microorganisms and we evaluated here the antimicrobial properties of S. scabiei. Under laboratory culture conditions, increasing peptone levels correlated with increased growth inhibitory properties of S. scabiei. Comparative metabolomics showed that production of S. scabiei siderophores (desferrioxamines, pyochelin, scabichelin and turgichelin) increased with the quantity of peptone thereby suggesting that they participate in growth inhibition. Mass spectrometry imaging further confirmed that the zones of secreted siderophores and growth inhibition coincided. Moreover, either the repression of siderophore production or the neutralization of their iron-chelating activity both led to increased microbial growth. Replacement of peptone by natural nitrogen sources regularly used as fertilizers such as ammonium nitrate, ammonium sulfate, sodium nitrate, and urea also triggered siderophore production in S. scabiei. The observed effect is not mediated by alkalinization of the medium as increasing the pH without providing additional nitrogen sources did not induce siderophore production. The nitrogen-induced siderophore production also inhibited the growth of important plant pathogens. Overall, our work suggests that not only the iron availability but also the nitrogen fertilizer sources could significantly impact the competition for iron between crop-colonizing microorganisms.

High-throughput genetics enables identification of nutrient utilization and accessory energy metabolism genes in a model methanogen.

Archaea are widespread in the environment and play fundamental roles in diverse ecosystems; however, characterization of their unique biology requires advanced tools. This is particularly challenging when characterizing gene function. Here, we generate randomly barcoded transposon libraries in the model methanogenic archaeon Methanococcus maripaludis and use high-throughput growth methods to conduct fitness assays (RB-TnSeq) across over 100 unique growth conditions. Using our approach, we identified new genes involved in nutrient utilization and response to oxidative stress. We identified novel genes for the usage of diverse nitrogen sources in M. maripaludis including a putative regulator of alanine deamination and molybdate transporters important for nitrogen fixation. Furthermore, leveraging the fitness data, we inferred that M. maripaludis can utilize additional nitrogen sources including ʟ-glutamine, ᴅ-glucuronamide, and adenosine. Under autotrophic growth conditions, we identified a gene encoding a domain of unknown function (DUF166) that is important for fitness and hypothesize that it has an accessory role in carbon dioxide assimilation. Finally, comparing fitness costs of oxygen versus sulfite stress, we identified a previously uncharacterized class of dissimilatory sulfite reductase-like proteins (Dsr-LP; group IIId) that is important during growth in the presence of sulfite. When overexpressed, Dsr-LP conferred sulfite resistance and enabled use of sulfite as the sole sulfur source. The high-throughput approach employed here allowed for generation of a large-scale data set that can be used as a resource to further understand gene function and metabolism in the archaeal domain.IMPORTANCEArchaea are widespread in the environment, yet basic aspects of their biology remain underexplored. To address this, we apply randomly barcoded transposon libraries (RB-TnSeq) to the model archaeon Methanococcus maripaludis. RB-TnSeq coupled with high-throughput growth assays across over 100 unique conditions identified roles for previously uncharacterized genes, including several encoding proteins with domains of unknown function (DUFs). We also expand on our understanding of carbon and nitrogen metabolism and characterize a group IIId dissimilatory sulfite reductase-like protein as a functional sulfite reductase. This data set encompasses a wide range of additional conditions including stress, nitrogen fixation, amino acid supplementation, and autotrophy, thus providing an extensive data set for the archaeal community to mine for characterizing additional genes of unknown function.

Metabolomic Profiling and Biological Investigation of the Marine Sponge-Derived Fungus Aspergillus sp. SYPUF29 in Response to NO Condition.

Marine-derived fungi are assuming an increasingly central role in the search for natural leading compounds with unique chemical structures and diverse pharmacological properties. However, some gene clusters are not expressed under laboratory conditions. In this study, we have found that a marine-derived fungus Aspergillus sp. SYPUF29 would survive well by adding an exogenous nitric oxide donor (sodium nitroprusside, SNP) and nitric oxide synthetase inhibitor (L-NG-nitroarginine methyl ester, L-NAME) in culture conditions. Moreover, using the LC-MS/MS, we initially assessed and characterized the difference in metabolites of Aspergillus sp. SYPUF29 with or without an additional source of nitrogen. We have found that the metabolic pathway of Arginine and proline metabolism pathways was highly enriched, which was conducive to the accumulation of alkaloids and nitrogen-containing compounds after adding an additional source of nitrogen in the cultivated condition. Additionally, the in vitro anti-neuroinflammatory study showed that the extracts after SNP and L-NAME were administrated can potently inhibit LPS-induced NO-releasing of BV2 cells with lower IC50 value than without nitric oxide. Further Western blotting assays have demonstrated that the mechanism of these extracts was associated with the TLR4 signaling pathway. Additionally, the chemical investigation was conducted and led to nine compounds (SF1-SF9) from AS1; and six of them belonged to alkaloids and nitrogen-containing compounds (SF1-SF6), of which SF1, SF2, and SF8 exhibited stronger activities than the positive control, and showed potential to develop the inhibitors of neuroinflammation.

Production of Amylase by Solid State Fermentation Using Agricultural Waste

This study presents a comprehensive investigation into the production of amylase, a crucial enzyme with wide-ranging industrial applications, using locally sourced substrates from Kachchh, Gujarat. The research employed the Bacillus licheniformis strain and substrates such as coconut, rice husk, wheat bran, paddy straw, and maize straw. The study found paddy straw to be the most promising substrate for amylase production. The research also systematically optimized various process parameters for amylase production in Solid-State Fermentation (SSF) using the One Variable at a Time (OVAT) method. These parameters included incubation period, temperature, inoculum level, additional carbon sources, starch concentrations, additional nitrogen sources, initial pH, different mineral salt ions, initial moisture level, and surfactants. The results showed that the optimal conditions for maximum amylase yield were an incubation period of 48 hours, an incubation temperature of 35°C, an inoculum level of 10%, starch as the additional carbon source, a starch concentration of 2.5%, yeast extract as the additional nitrogen source, an initial pH of 7, NaCl as the mineral salt, an initial moisture level of 75%, and Tween 80 as the surfactant. This research provides a reliable and sustainable approach to enzyme production, offering valuable insights for the optimization of the solid-state fermentation process for maximum amylase production.

Nanoarchitectonics of porous carbon derived from urea-impregnated microporous triazine polymer in KOH activator for adsorptive removal of sulfonamides from water

A microporous covalent-organic polymer (triazine polymer, referred to as MCTP), was synthesized and subsequently carbonized, after loading urea and KOH (serving as an additional nitrogen source and activator, respectively), through high-temperature pyrolysis. This process resulted in materials named KUCDCs, which exhibited high porosity and a broader range of pore sizes compared to carbon materials produced without the addition of urea and KOH, referred to as CDC. KUCDCs, CDC, and commercially available activated carbon (AC) were evaluated for their ability to remove sulfonamide drugs, sulfamethoxazole (SMX) and sulfachlorpyridazine (SCP), from aqueous solution. Among these materials, KUCDC-800, which was carbonized at a temperature of 800 °C, demonstrated superior adsorption performances for sulfonamides, attributed to its high porosity, nitrogen content, and presence of surface oxygen groups. The adsorption capacities for SMX and SCP on KUCDC were notably higher than those on AC and MDC, with maximum capacities (Q0) of 619 and 554 mg/g for SMX and SCP, respectively. Notably, KUCDC-800 stands out as a recyclable adsorbent with the highest reported Q0 for SMX to date under near-neutral conditions. The exceptional performance of KUCDC in adsorbing SMX could be explained by its high porosity and surface functionalities for hydrogen bonding interactions with the adsorbate.

A supported Ni2 dual-atoms site hollow urchin-like carbon catalyst for synergistic CO2 electroreduction

Dual-atoms catalysts (DACs), while inheriting the advantages of maximum atom utilization ratio and excellent selectivity of single-atom catalysts (SACs), can better enhance the catalytic activity through the synergy of adjacent atoms. Therefore, DACs are considered to be very potential catalysts for CO2 to CO conversion. Its catalytic activity is greatly influenced by the coordination environment and morphology. Here, hollow urchin-like NiNC catalysts (Ni-NC(HU)-x, x = 100, 50, 25, 0) were synthesized using urchin-like nickel particles as template. By adjusting the amount of additional nitrogen source, the percentage content of pyridinic-N was adjusted as well as further affecting the coordination environment. Among them, Ni-NC(HU)-50, which had the highest content of pyridinic-N, formed a dual-atoms coordination structure and had the best catalytic performance that the CO Faradaic efficiency (FECO) reached 97.2 % at −0.9 V vs. reversible hydrogen electrode (RHE) and sustained above 95 % within 50 h. In-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations showed that Ni-NC(HU)-50 exhibited the best performance of CO2 reduction reaction (CO2RR) by lowering the *COOH formation free energy barrier and its favorable dual desorption mechanism of *COL and *COB.

Fungus-mediated preparation of porous carbon based on wheat straw: Efficient removal of chromium and enhanced electrochemical properties

Herein, a lignocellulose-degrading fungus (Irpex lacteus) was used to solidly ferment wheat straw to enhance its performance by improving its native structure and introducing an additional nitrogen source. Subsequently, the fungal-mediated wheat straw porous carbon (IL-WSPC-700) was prepared by the NaOH-activated etching method. The results of the characterization confirmed that the fungal treatment could successfully disrupt the natural structure of the wheat straw, resulting in better etching during the subsequent alkali activation process. The IL-WSPC-700 exhibited a larger specific surface area (3452.42 m2 g−1) with more micropores, which positively impacted the adsorption of heavy metal Chromium (Cr, the oxidation number was 6) by the material, and the highest adsorption capacity (678.41 mg g−1) was observed at pH value = 1. In addition, the electrode prepared by IL-WSPC-700 had a high specific capacitance of 310.7 F g−1 at 1 A g−1 current density and maintained 95.83 % of the specific capacitance after 5000 cycles in the two-electrode system. The above experiments confirmed the success of the fungal treatment strategy, IL-WSPC-700 had excellent adsorption and electrochemical performances. This study is an attempt to design and prepare adsorbents and electrode materials using microbial hypha and agricultural wastes. It could provide a reference for the preparation of high-performance materials via the synergistic effect of microbial assistance and alkali etching.

Ethanol Production from a Mixture of Waste Tissue Paper and Food Waste through Saccharification and Mixed-Culture Fermentation

This study focused on the co-fermentation of food waste and tissue paper to produce ethanol, which will eliminate the need for additional nitrogen sources and nutrients, thereby reducing production costs. In response to the inhibitory effect of the high concentrations of glucose present in mixed-substrate hydrolysates on xylose fermentation, a co-fermentation process using Saccharomyces cerevisiae and Candida shehatae was proposed. This approach reduced the fermentation time by 24 h, increased the xylose utilization rate to 88%, and improved the ethanol yield from 41% to 46.5%. The impact of external conditions and corresponding optimization were also analyzed in this process. The optimum conditions were a 1:3 ratio of Saccharomyces cerevisiae to Candida shehatae, a pH of 5, and shaking at 150 r/min, and by employing dynamic temperature control, the ethanol production was increased to 21.98 g/L. Compared to conventional processes that only use Saccharomyces cerevisiae, this method enhanced the ethanol yield from 41% to 49%.

The Nitrogen Content in the Fruiting Body and Mycelium of Pleurotus Ostreatus and Its Utilization as a Medium Component in Thraustochytrid Fermentation.

Following the idea of a circular bioeconomy, the use of side streams as substitutes for cultivation media (components) in bioprocesses would mean an enormous economic and ecological advantage. Costly compounds in conventional media for the production of the triterpene squalene in thraustochytrids are the main carbon source and complex nitrogen sources. Among other side streams examined, extracts from the spent mycelium of the basidiomycete Pleurotus ostreatus were best-suited to acting as alternative nitrogen sources in cultivation media for thraustochytrids. The total nitrogen (3.76 ± 0.01 and 4.24 ± 0.04%, respectively) and protein (16.47 ± 0.06 and 18.57 ± 0.18%, respectively) contents of the fruiting body and mycelium were determined. The fungal cells were hydrolyzed and extracted to generate accessible nitrogen sources. Under preferred conditions, the extracts from the fruiting body and mycelium contained 73.63 ± 1.19 and 89.93 ± 7.54 mM of free amino groups, respectively. Cultivations of Schizochytrium sp. S31 on a medium using a mycelium extract as a complex nitrogen source showed decelerated growth but a similar squalene yield (123.79 ± 14.11 mg/L after 216 h) compared to a conventional medium (111.29 ± 19.96 mg/L, although improvable by additional complex nitrogen source).

Cr5.7Si2.3P8N24-A Chromium(+IV) Nitridosilicate Phosphate with Amphibole-Type Structure.

The first nitridic analog of an amphibole mineral, the quaternary nitridosilicate phosphate Cr5.7Si2.3P8N24 was synthesized under high-pressure high-temperature conditions at 1400 °C and 12 GPa from the binary nitrides Cr2N, Si3N4 and P3N5, using NH4N3 and NH4F as additional nitrogen source and mineralizing agent, respectively. The crystal structure was elucidated by single-crystal X-ray diffraction with microfocused synchrotron radiation (C2/m, a=9.6002(19), b=17.107(3), c=4.8530(10) Å, β=109.65(3)°). The elemental composition was analyzed by energy dispersive X-ray spectroscopy. The structure consists of vertex-sharing PN4-tetrahedra forming zweier double chains and edge-sharing (Si,Cr)-centered octahedra forming separated ribbons. Atomic resolution scanning transmission electron microscopy shows ordered Si and Cr sites next to a disordered Si/Cr site. Optical spectroscopy indicates a band gap of 2.1 eV. Susceptibility measurements show paramagnetic behavior and support the oxidation state Cr+IV, which is confirmed by EPR. The comprehensive analysis expands the field of Cr-N chemistry and provides access to a nitride analog of one of the most prevalent silicate structures.

Cr5.7Si2.3P8N24—A Chromium(+IV) Nitridosilicate Phosphate with Amphibole‐Type Structure

AbstractThe first nitridic analog of an amphibole mineral, the quaternary nitridosilicate phosphate Cr5.7Si2.3P8N24 was synthesized under high‐pressure high‐temperature conditions at 1400 °C and 12 GPa from the binary nitrides Cr2N, Si3N4 and P3N5, using NH4N3 and NH4F as additional nitrogen source and mineralizing agent, respectively. The crystal structure was elucidated by single‐crystal X‐ray diffraction with microfocused synchrotron radiation (C2/m, a=9.6002(19), b=17.107(3), c=4.8530(10) Å, β=109.65(3)°). The elemental composition was analyzed by energy dispersive X‐ray spectroscopy. The structure consists of vertex‐sharing PN4‐tetrahedra forming zweier double chains and edge‐sharing (Si,Cr)‐centered octahedra forming separated ribbons. Atomic resolution scanning transmission electron microscopy shows ordered Si and Cr sites next to a disordered Si/Cr site. Optical spectroscopy indicates a band gap of 2.1 eV. Susceptibility measurements show paramagnetic behavior and support the oxidation state Cr+IV, which is confirmed by EPR. The comprehensive analysis expands the field of Cr−N chemistry and provides access to a nitride analog of one of the most prevalent silicate structures.

Coproduction of inulinase and invertase by Galactomyces geotrichum in whey-based medium and evaluation of additional nutrients

The purpose of this research was to evaluate the suitability of whey as an effective medium for the coproduction of inulinase and invertase by an oleaginous yeast Galactomyces geotrichum and to investigate the effects of some additional carbon and nitrogen sources. The nutritional factors and composition of the medium have a great impact on the production pathways of microbial enzymes. To deepen the research, a Taguchi design was employed to quickly scan the best conditions. First, the cheese whey was partly deproteinized and investigated as the sole medium for the yeast. The next step was performed to study the effects of inulin, sucrose and lactose as carbon sources and ammonium sulfate, yeast extract and casein as nitrogen sources. All analyses (Taguchi and ANOVA) were performed using Minitab software. Whey-based medium without any additional carbon and nitrogen sources gave inulinase and invertase activities as 54.6 U/mL and 47.4 U/mL, respectively. Maximum inulinase activity was obtained as 77.9 U/mL using inulin as the carbon source without any nitrogen source. The highest I/S ratio was found as 2.08. On the other hand, the highest invertase activity was carried out as 50.85 U/mL in whey-based medium using lactose as carbon source without any additional nitrogen source. This is the first report about partly deproteinized whey-based medium utilization for simultaneous inulinase and invertase production by G. geotrichum TS-61. Moreover, the effects of carbon and nitrogen sources were investigated in detail.

Kinetics of bacterial cellulose formation in soybean-boiled wastewater medium during fermentation utilizing real-time image processing

The bacterial cellulose (BC) fermentation is affected by environmental growth conditions such as pH, temperature, and turbidity. During the fermentation, a real-time image processing method was applied to observe the BC growth by using soybean-boiled wastewater and coconut water as a mixture. Cellulose will be produced and discharged into the medium throughout the fermentation process to form BC sheets, which will gradually become visible. The purpose of this study is to investigate the correlation between the growth parameters of BC and to analyze the formation of BC kinetically, using the Gompertz model on medium without additional nitrogen source and medium with additional nitrogen sources during the fermentation process. The strongest correlation result was found between time and thickness of BC formed without an additional nitrogen source, and with sodium glutamate as the nitrogen source. The Gompertz model equation was suitable for predicting the kinetics of BC formation time and thickness based on the available data. Both mediums exhibited three clusters that represented the adaptation stage, the exponential stage, and the stationary stage during the fermentation process. The addition of a nitrogen source to the medium resulted in thicker BC sheets compared to the medium without this addition.

Transition metal nitride/sulfide nanoparticles attached to nitrogen-doped carbon nanotubes synthesized by modified black powder detonation for efficient overall water splitting

To overcome the energy crisis, the rational construction of efficient electrolytic water catalysts is urgently required. Herein, an innovative proposal was presented for the preparation of self-supported electrolytic water catalysts on nickel foam (NF) substrates using modified black powder (BP) detonation method. The transient high temperature of the controlled detonation can obtain a variety of highly active catalytic components. First, carbon nanotubes (CNTs) were immobilized on NF by electroplating nickel to improve the pore utilization and electrical conductivity of NF. The unique hollow channel structure and extensive surface area of CNTs facilitated the attachment of the active catalysts. The introduction of Co metal salt not only controlled the reaction degreed effectively but also served as an effective transition metal source. With sulfur (S) source in BP and the additional nitrogen (N) source, the detonation successfully produced nano Co5.47N and Ni3S2. Nanocrystals Co5.47N and Ni3S2 along with N-doped CNTs, acquired via transient high-temperature reaction, were abound in defects. Consequently, the obtained sample exhibited excellent catalytic activities for both hydrogen evolution and oxygen evolution reactions. A remarkable overall water-splitting was achieved at a voltage of 1.52 V at 10 mA cm−2 in a two-electrode water electrolysis system.

Optimization of cultural parameters for lipase production by indigenous stenotrophomonas sp. And pseudomonas aeruginosa isolated from lipid-rich environments

The present study aims to identify prospective lipase-producing bacteria and optimize different culture parameters to produce maximum lipase. A total of 37 lipase-positive bacteria were isolated from lipid-rich environments. Among them, strains S1N-2 and S10P-1 were found to have potential and were molecularly identified as Stenotrophomonas species ICMM10 and Pseudomonas aeruginosa BA7823, respectively. For maximum lipase production, the optimum pH was 7 and the temperature was 37ºC. Using these conditions, the isolates were grown on media with additional carbon and nitrogen sources along with different inoculum concentrations. The maximum amount of lipase produced by Stenotrophomonas sp. ICMM10 was 136.47 ± 1.63 U/ml, which is 5-fold higher than before. Pseudomonas aeruginosa BA7823 produced a maximum lipase of 96.33 ± 0.21 U/ml, which was about 9-fold higher than before. These results would provide useful information about lipase production by indigenous isolates, which may be employed as a potential bacterial lipase source of biotechnological interest. Bangladesh J. Bot. 52(4): 979-988, 2023 (December)

The effect of additional nitrogen source on iron phthalocyanine-based nanocarbon catalysts for oxygen reduction reaction in acidic media

The focus in the development of catalysts doped with transition metals aims to replace platinum group metal catalysts in fuel cells. However, these non-precious metal catalysts exhibit limited performance in acidic environment for the oxygen reduction reaction (ORR) due to issues such as metal agglomeration and the subsequent loss of active sites. Herein, we synthesised catalysts doped with iron and nitrogen on a composite material consisting of carbide-derived carbon (CDC) and graphene (G), employing an additional nitrogen source dicyandiamide (DCDA), denoted as FeN-CDC/G/DCDA. Our physico-chemical analysis unveiled that the inclusion of DCDA was effective in mitigating metal agglomeration during the synthesis process and increasing the presence of Fe-Nx sites in the catalysts. Notably, the FeN-CDC/G/DCDA catalyst exhibited enhanced ORR activity in acid media with half-wave potential (E1/2) of 0.76 V, surpassing the performance of the FeN-CDC/G catalyst, which had an E1/2 value of 0.70 V. Furthermore, the rotating ring-disk electrode results indicated a reduced formation of hydrogen peroxide when employing the FeN-CDC/G/DCDA catalyst. The findings from this study represent a significant step towards the development of efficient catalysts for fuel cells, underscoring the pivotal role of additional nitrogen doping and its positive impact on the ORR performance.

Enhanced production of L-serine in Escherichia coli by fermentation process optimization and transcriptome sequencing

In this study, the performance of Escherichia coli fermentation for L-serine production was improved by fermentation process optimization and transcriptomic analysis. The induction point, induction temperature, dissolved oxygen level and nitrogen source addition in the fed batch fermentation were studied separately to determine the optimal fermentation process. And transcriptome sequencing was applied to the fermentation process to reveal the key metabolic pathways affecting L-serine production. The results showed that the highest titer of L-serine reached 45.66 g/L with a yield of 0.39 g/g when the induction point, induction temperature, dissolved oxygen level and nitrogen source addition were OD600 = 15, 39 ℃, 40% and 10%, respectively. Transcriptome sequencing results showed that cysteine and methionine metabolism were closely related to L-serine synthesis, and the addition of L-cysteine to the medium promoted cell growth and sustained accumulation of L-serine.

Towards anaerobic digestate valorization to recover fertilizer nutrients: Elaboration of technology and profitability analysis

The study aimed to develop a technology for creating granular fertilizers, containing amino acids, based on food waste digestate. Pork hemoglobin (Ntot: 14.9 ± 1.5%, C: 47.2 ± 4.7%) served as an additional source of nitrogen and organic carbon. The proposed method comprises four unit processes: (1) chemical hydrolysis of raw materials with a mixture of sulfuric (VI) acid and phosphoric (V) acid, (2) neutralization with solid potassium hydroxide and correction of the composition with minerals (sulfate salts of copper, manganese, zinc and iron), (3) granulation with a mixture of biomass combustion, potato starch and peat, and (4) drying the granules. The prepared formulation meets the requirements of European Parliament Regulation 2019/1009 and is classified as PFC 1(B)(I): solid organo-mineral fertilizer (N: 4.49 ± 0.45%, C: 35.0 ± 3.50%, P2O5: 2.83 ± 0.57%, K2O: 4.78 ± 0.96%). The forms of nutrients were determined in accordance with current PN-EN standards. The effect of amino acid fertilizer on cucumber plants (Cucumis sativus, W. Legutko) was studied in 10-day germination tests under normal, salinity and drought conditions. It was noted that a low dose of the preparation under normal conditions had a stimulating effect on root development, while higher supplementation positively affected the aboveground parts of the plants. Under drought conditions, plants accumulated higher amounts of free amino acids, particularly glutamic acid, arginine, glycine, phenylalanine, serine and tryptophan. A significant portion of the study focused on the economic analysis, which included financial calculations for the production of the proposed fertilizer, an evaluation of profitability, and a sensitivity analysis.

Macrogenomic analysis of the effects of aqueous-phase from hydrothermal carbonation of sewage sludge on nitrogen metabolism pathways and associated bacterial communities during composting

The effects of aqueous phases (AP) formed from hydrothermal carbonation of sewage sludge (with or without rice husk) as moisture regulators of nitrogen metabolism pathways during composting are currently unclear. Macrogenomic analyses revealed that both APs resulted in notably changes in bacterial communities during composting; increased levels of nitrogen assimilation, nitrification, and denitrification metabolic pathways; and decreased levels of nitrogen mineralization metabolic pathways. Genes associated with nitrogen assimilation and mineralization accounted for 34–41% and 32–40% of the annotated reads related to nitrogen cycling during composting, respectively, representing them as the most abundant nitrogen metabolism processes. The gudB and norB were identified as key genes for nitrogen mineralization and nitrous oxide emission, respectively. This research offers a better understanding of the effects of additional nitrogen sources on nitrogen metabolism pathways during composting.

Magnetized algae catalyst by endogenous N to effectively trigger peroxodisulfate activation for ultrafast degraded sulfathiazole: Radical evolution and electron transfer

An innovative Fe–N co-coupled catalyst MN-2 was prepared from waste spirulina by co-pyrolysis as a highly active carbon-based catalyst for the activation of peroxydisulfate (PDS) for the degradation of sulfathiazole (ST). The protein-rich raw material Spirulina provided sufficient N during the pyrolysis process, thus achieving N doping without an additional nitrogen source, optimizing the interlayer structure of the biochar material and effectively inhibiting the leaching of the ligand metal Fe. MN-2 showed highly efficient catalytic activity for peroxydisulfate (PDS), with a degradation efficiency of 100% for ST within 30 min and a kinetic constant (kobs) reached 0.306 min−1, benefiting from the excellent adsorption ability of MN-2 forming MN-2-PDS* complexes and the electron transfer process generated by Fe3+ and Fe2+ cycling, oxygen-containing functional groups. The effects of PDS dosage, initial pH and coexisting anions on the oxidation process were also investigated. Free radical quenching, electron paramagnetic resonance and electrochemical measurements were employed to explain the hydroxyl (·OH) and sulfate (SO4·−) as the dominant active species and the electron transfer effect on the removal of ST. MN-2 maintained a ST removal rate of 84% after four recycling experiments, showing a high reusability performance. This work provides a simple way to prepare magnetized N-doped biochar, a novel catalyst (MN-2) for efficient activation of PDS for ST degradation, and a feasible method for removing sulfanilamide antibiotics in water environment.