The Effects of Three Mineral Nitrogen Sources and Zinc on Maize and Wheat Straw Decomposition and Soil Organic Carbon

The incorporation of straw in cultivated ifelds can potentially improve soil quality and crop yield. However, the presence of recalcitrant carbon compounds in straw slow its decomposition rate. The objective of this study was to determine the effects of different nitrogen sources, with and without the application of zinc, on straw decomposition and soil quality. Soils were treated with three different nitrogen sources, with and without zinc： urea （CO（NH2）2）, ammonium sulfate （（NH4）2SO4）, and ammonium chloride （NH4Cl）. The combined treatments were as follows：maize （M） and wheat （W） straw incorporated into urea-, ammonium sulfate-, or ammonium chloride-treated soil （U, S, and C, respectively） with and without zinc （Z） （MU, MUZ, WU, WUZ;MS, MSZ, WS, WSZ;MC, MCZ, WC, WCZ, respectively）;straw with zinc only （MZ, WZ）;straw with untreated soil （MS, WS）;and soil-only or control conditions （NT）. The experiment consisted of 17 treatments with four replications. Each pot contained 150 g soil and 1.125 g straw, had a moisture content of 80%of the ifeld capacity, and was incubated for 53 days at 25°C. The rates of CO2-C emission, cumulative CO2-C evolution, total CO2 production in the soils of different treatments were measured to infer decomposition rates. The total organic carbon （TOC）, labile organic carbon （LOC）, and soil microbial biomass in the soils of different treatments were measured to infer soil quality. All results were signiifcantly different （P〈0.05） with the exception of the labile organic carbon （LOC）. The maize and wheat straw showed different patterns in CO2 evolution rates. For both straw types, Zn had a synergic effect with U, but an antagonistic effect with the other N sources as determined by the total CO2 produced. The MUZ treatment showed the highest decomposition rate and cumulative CO2 concentration （1 120.29 mg/pot）, whereas the WACZ treatment had the lowest cumulative CO2 concentration （1 040.57 mg/pot）. The addition of NH4Cl resulted in the highest total organic carbon （TOC） concentration （11.59 mg kg-1）. The incorporation of wheat straw resulted in higher microbial biomass accumulation in soils relative to that of the maize straw application. The results demonstrate that mineral N sources can affect the ability of microorganisms to decompose straw, as well as the soil carbon concentrations.

Influence comparison of N2 and NH3 nitrogen sources on AlN films grown by halide vapor phase epitaxy

A comparison of the nitrogen sources(N2 and NH3)influence on AlN films grown by high-temperature halide vapor phase epitaxy(HVPE)is reported.The x-ray rocking curves(XRCs)indicate that the full width at half maximum(FWHM)of(0002)plane for AlN films using N2 as nitrogen source is generally smaller than that using NH3.Optical microscope and atomic force microscope(AFM)results show that it is presently still more difficult to control the crack and surface morphology of AlN films with thicknesses of 5-10µm using N2 as the nitrogen source compared to that using NH3.Compared with one-step growth,two-step growth strategy has been proved more effective in stress control and reducing the density of threading dislocations for AlN epilayers using N2 as the nitrogen source.These investigations reveal that using N2 as nitrogen source in HVPE growth of AlN is immature at present,but exhibits great potential.

Influence of nitrogen sources on growth and mycotoxin production by isolates of Pyrenophora tritici-repentis from wheat

The fungus Pyrenophora tritici-repentis(Died.) Drechs. infects the leaves and kernels of wheat,causing tan spot and red smudge, respectively. Isolates of P. tritici-repentis have been reported to be both phytopathogenic and mycotoxigenic. This research investigates the influence of nitrogen sources on growth and production of mycotoxins by eight different isolates of P. tritici-repentis. A synthetic agar medium(SAM) was used with different nitrogen sources, both inorganic [(NH4Cl, NH4NO3and(NH4)2SO4)] and organic(L-alanine, L-histidine, and L-lysine), at a concentration of 37.5 mmol L-1. Individual isolates exhibited different growth rates that varied according to the nitrogen source added to the medium. The choice of nitrogen source also had a major effect on production of the mycotoxins emodin, catenarin and islandicin. The highest concentrations of emodin, 54.40 ± 4.46 μg g-1, 43.07 ± 23.39 μg g-1and28.91 ± 4.64 μg g-1of growth medium, were produced on the complex medium(V8-potato dextrose agar) by the isolates Alg-H2, 331-2 and TS93-71 B, respectively. A relatively high concentration of emodin also was produced by isolates Az35-5(28.29 ± 4.71 μg g-1of medium)and TS93-71B(27.03 ± 4.09 μg g-1of medium) on synthetic medium supplemented with L-alanine. The highest concentrations of catenarin(174.54 ± 14.46 μg g-1and 104.87 ±6.13 μg g-1of medium) were recorded for isolates TS93-71 B and Alg-H2 on synthetic medium supplemented with L-alanine and NH4 Cl, respectively. The highest concentration of islandicin(4.64 ± 0.36 μg g-1medium) was observed for isolate 331-2 in the presence of L-lysine. There was not a close relationship between mycelial growth and mycotoxin production by the fungal isolates. This is the first report on the influence of nitrogen sources on the production of mycotoxins by P. tritici-repentis.

Evidence of Oil Sources and Migration in Triassic-Jurassic Reservoirs in the South Tianhuan Depression of the Ordos Basin, China Based on Analysis of Biomarkers and Nitrogen-Bearing Compounds

The Ordos Basin is an important intracontinental sedimentary basin in western China for its abundant Mesozoic crude oil resources. The southern part of the Tianhuan Depression is located in the southwestern marginal area of this Basin, in which the Jurassic and Triassic Chang-3 are the main oil-bearing strata. Currently, no consensus has been reached regarding oil source and oil migration in the area, and an assessment of oil accumulation patterns is thus challenging. In this paper, the oil source, migration direction, charging site and migration pathways are investigated through analysis of pyrrolic nitrogen compounds and hydrocarbon biomarkers. Oil source correlations show that the oils trapped in the Jurassic and Chang-3 reservoirs were derived from the Triassic Chang-7 source rocks. The Jurassic and Chang-3 crude oils both underwent distinct vertical migration from deep to shallow strata, indicating that the oils generated by Chang-7 source rocks may have migrated upward to the shallower Chang-3 and Jurassic strata under abnormally high pressures, to accumulate along the sand bodies of the ancient rivers and the unconformity surface. The charging direction of the Jurassic and Chang-3 crude oils is primarily derived from Mubo, Chenhao, and Shangliyuan, which are located northeast of the southern Tianhuan Depression, with oils moving toward the west, southwest, and south. The results show that an integration of biomarker and nitrogen-bearing compound analyses can provide useful information about oil source, migration, and accumulation.

Low-Temperature Synthesis of Nano-AlN Based on Solid Nitrogen Source by Plasma-Assisted Ball Milling

Plasma-assisted ball milling was carried out on the Al+C3H6N6 system and Al+C_(4)H_(4)N_(4) system,respectively.The phase structure,functional groups and synthesis mechanism were analyzed by XRD and FT-IR,and the differences in the synthesis process of nano-AlN with different solid nitrogen sources were discussed.The results show that C3H6N6 has a stable triazine ring structure,and its chemical bond is firm and difficult to break,so AlN cannot be synthesized directly by solid-solid reaction at room temperature.However,there are a large number of nitrile groups(-CN)and amino groups(-NH_(2))in C_(4)H_(4)N_(4) molecules.Under the combined action of plasma bombardment and mechanical energy activation,C_(4)H_(4)N_(4) molecules undergo polycondensation and deamination,so that the ball milling tank is filled with a large number of active nitrogen-containing groups such as N=,≡N,etc.These groups and ball milling activated Al can synthesize nano-AlN at room temperature,with a conversion rate of 92%.SEM,DSC/TG analysis showed that the powder obtained by ball milling was formed by soft agglomeration of many fine primary particles about 50–80 nm.The surface morphology of the powder was loose and porous,and it had strong activity.After annealing at 800℃,the conversion rate of the Al+C_(4)H_(4)N_(4) system reached 99%.

Effects of Carbon and Nitrogen Additions on Soil Microbial Biomass Carbon and Enzyme Activities Under Rice Straw Returning

The effects of different amounts of carbon and nitrogen sources on the soil microbial biomass carbon,dissolved organic carbon and related enzyme activities were studied by the simulation experiment of rice straw returning to the field,and the mechanism of the decomposition of rice straw returning to the field was discussed.Completely randomized experiment of the two factors of the three levels was designed,and a total of nine treatments of indoor soil incubation tests were conducted.Full amount of rice straw was applied to the soil in this simulation experiment and different amounts of brown sugar and urea were added in the three levels of 0(no carbon source and nitrogen source),1(low levels of carbon and nitrogen sources)and 2(high levels of carbon and nitrogen sources),respectively.The results showed that the addition of different amounts of carbon and nitrogen sources to the rice straw could increase the soil carbon content.Compared with T0N0,the microbial biomass carbon of T2N2 was increased significantly by 170.48%;the dissolved organic carbon content of T1N2 was significantly increased by 58.14%and the free humic acid carbon contents of T0N2,T1N1 and T2N0 were significantly increased by 56.16%and 45.55%and 47.80%,respectively;however,there were no significant differences among those of treatments at later incubation periods.The addition of different carbon and nitrogen sources could promote the soil enzyme activities.During the incubation period,all of the soil enzyme activities of adding sugar and urea were higher than those of T0N0 treatment.Therefore,the addition of different amounts of carbon and nitrogen sources to rice straw returning could improve soil microbial biomass carbon content,dissolved organic carbon and soil enzyme activities.

Influences of dietary protein sources and crude protein levels on intracellular free amino acid profile in the longissimus dorsi muscle of finishing gilts

Background： The current study was carried out to determine effects of dietary protein source and crude protein（CP）level on carcass characteristics, meat quality, and muscle amino acid（AA） profile in finishing gilts. The experiment was designed as a 2 × 2 factorial arrangement with two sources of dietary proteins（cottonseed meal, CSM vs. soybean meal, SBM） and two levels of CP（12 % vs. 14 %, as-fed basis）. Seventy-two crossbred gilts（89.5 ± 0.9 kg） were allotted to one of four dietary treatments in a randomized complete block design for a period of 28 d. All diets were formulated to be isoenergetic and similar concentrations of standardized ileal digestible essential AA covering the nutrient requirements of pigs.Results： Growth, carcass characteristics and meat quality were not affected by dietary protein source nor crude protein level（P ＆gt; 0.10） except that average daily feed intake was increased by CSM diets（P = 0.03）. Gilts offered reduced protein diets had lower muscle p H45min（P 〈 0.05）. Neither dietary protein source nor crude protein level influenced N deposition. However, reduced protein diets decreased N intake, N excretion, and serum urea nitrogen content, whilst improved N efficiency（P 〈 0.01）. CSM diets increased N intake（P = 0.04）,but did not depress N efficiency. The concentrations of phenylalanine, tryptophan, cysteine and tyrosine（P 〈 0.05） of the longissimus muscle were decreased when gilts offered CSM diets, while muscle intracellular free valine concentration was increased（P = 0.03）. The gilts offered reduced protein diets had greater intracellular concentrations of free methionine, lysine, and total AA in muscle（P 〈 0.05）.Conclusion： These results suggest that CSM could replace SBM as a primary protein source in finishing pig diets in terms of performance, N efficiency, carcass characteristics, and meat quality, but decrease the concentrations of muscle specific AA. Furthermore, the reduced protein diet played an important role in increasing muscle intracellular concentrations of specific free amino acids（FAA）, and in reducing the relative ratios of specific FAA to lysine in longissimus dorsi muscle of pig, whose biological meaning needs further studies.

A NEW FACILE METHOD FOR THE SYNTHESIS OF AZACROWN ETHERS BY USING BENZYLSULFONAMIDE AS A SOURCE OF NITROGEN

Benzylsulfonamide was used as a source of nitrogen in the syn- thesis of azacrown ethers,and the cyclic intermediates were easily deben- zylsulfonylated by treating with CaF_2/H_2SO_4 to afford the azacrown ethers.

Characteristics and Culture Conditions of a Bioflocculant Produced by Penicillium sp.

Objective To study the characteristics of a bioflocculant named MBF7 produced by Penicillum strain HHE-P7 and the effects of cultivation conditions on bioflocculant production. Methods The chemical group in the bioflocculant molecules was shown by Fourier transform infrared （FTIR） spectra, and the average molecular weight of MBF7 was estimated by gel permeation chromatography. The effects of medium components on bioflocculant production and flocculating activity were studied. Results Phospho-, amino-, hydroxyl, and carboxyl groups were the major fractions of MBF7, and the molecule weight was about 3.0 × 10^5 Da. In addition, the carbon and nitrogen sources favorable for the bioflocculant production were glucose and yeast extract respectively. When the initial pH of the medium was adjusted to 5.0, high flocculant efficiency could be achieved. Conclusion The bioflocculant MBF7 is a new macromolecule with high flocculating efficiency for Kaolin suspension, and could be produced under appropriate culture conditions.

Optimization of C/N ratio preparation of protein-rich and multi-enzymes feed thallus through synergic fermentation of mixed distillers'grains

A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method evaluating bacteria growth, called method of dry cell weighing by filtering is developed. For each combination of C and N, their initial and residual contents before and after fermentation respectively are determined. Then followed the calculation of utilization of C and N sources by the compound bacteria. The optimal C/N is finally located from among the utilization of C and N of several combinations and the weight of produced mass of oven dried thallus. The conditions of fermentation are: inoculum size 10%, temperature 30 0℃, rotational speed 170 r/min, shake culture time 48h. The best results obtained from orthogonal experiments are: maximum mass of oven dried thallus is 14 693g in a liter liquid medium, maximum utilization rate of carbon source is 98 13% and maximum utilization rate of nitrogen is 78 14%. Optimal C/N is 5 1.

Biological Characteristics and Culture Conditions of Hericium coralloides(Scop.)Pers.

[Objectives]To study the biological characteristics and culture conditions of Hericium coralloides(Scop.)Pers.[Methods]The wild H.coralloides strain of Changbai Mountain was used as the experimental material to conduct a single factor test on its biological characteristics.[Results]The ideal available carbon source and nitrogen source are glucose and ammonium sulfate,respectively,the pH is 3.5-4.0,and the temperature is 20-22℃.Through the orthogonal experiment of 4 factors and 4 levels,it is found that the degree of influence of the 4 factors on H.coralloides is temperature>pH>nitrogen source>carbon source.[Conclusions]The optimum conditions for the mycelium culture of H.coralloides:the carbon source is glucose,and the nitrogen source is yeast extract or peptone,and pH is 3.5-4.0,and temperature is 20-22℃.

Coupled effects of methane monooxygenase and nitrogen source on growth and poly-β-hydroxybutyrate(PHB)production of Methylosinus trichosporium OB3b

The coupled effects of nitrogen source and methane monooxygenase（MMO） on the growth and poly-β-hydroxybutyrate（PHB） accumulation capacity of methanotrophs were explored.The ammonia-supplied methanotrophs expressing soluble MMO（s MMO） grew at the highest rate, while N2-fixing bacteria expressing particulate MMO（p MMO） grew at the lowest rate. Further study showed that more hydroxylamine and nitrite was formed by ammonia-supplied bacteria containing p MMO, which might cause their slightly lower growth rate. The highest PHB content（51.0%） was obtained under nitrogen-limiting conditions with the inoculation of nitrate-supplied bacteria containing p MMO. Ammoniasupplied bacteria also accumulated a higher content of PHB（45.2%） with the expression of p MMO, while N2-fixing bacteria containing p MMO only showed low PHB production capacity（32.1%）. The maximal PHB contents of bacteria expressing s MMO were low, with no significant change under different nitrogen source conditions. The low MMO activity,low cell growth rate and low PHB production capacity of methanotrophs continuously cultivated with N2 with the expression of p MMO were greatly improved in the cyclic NO3-N2 cultivation regime, indicating that long-term deficiency of nitrogen sources was detrimental to the activity of methanotrophs expressing pMMO.

Transition from a maternal to external nitrogen source in maize seedlings

Maximizing NO3 uptake during seedling development is important as it has a major influence on plant growth and yield. However, little is known about the processes leading to, and involved in, the initiation of root NO3 uptake capacity in developing seedlings. This study examines the physiological processes involved in root NO3 uptake and metabolism, to gain an understanding of how the NO3 uptake system responds to meet demand as maize seedlings transition from seed N use to external N capture. The concentrations of seedderived free amino acids within root and shoot tissues are initially high, but decrease rapidly until stabilizing eight days after imbibition （DAI）. Similarly, shoot N% decreases, but does not stabilize until 12-13 DAI. Following the decrease in free amino acid concentrations, root NO3- uptake capacity increases until shoot N% stabilizes. The increase in root NO3 uptake capacity corresponds with a rapid rise in transcript levels of putative NO3 transporters, ZmNRT2.1 and ZmNRT2.2. The processes underlying the increase in root NO3- uptake capacity to meet N demand provide an insight into the processes controlling N uptake.

Improvement of Growth and Periplocin Yield of Periploca sepium Adventitious Root Cultures by Altering Nitrogen Source Supply

Objective To increase the ultimate yield of periplocin in Periploca sepium adventitious root cultures by a two-stage culture based on nitrogen source.Methods Firstly,the effects of nitrogen source(NH4+-NO3-) at different ratios and different total initial nitrogen amounts on the accumulation of biomass and secondary metabolites in adventitious root cultures of P.sepium were investigated,and growth and production media for the two-stage culture based on the above results were established.Results The highest biomass and periplocin content were obtained in the culture medium of 15 mmol/L total nitrogen amount with NH4+-NO3-(1:2) and 30 mmol/L total nitrogen amount with nitrate as the sole nitrogen source.By adopting a fed-batch cultivation strategy,the dry weight adventitious root,periplocin content and yield were increased by 136%,108%,and 389%,respectively when compared with those of the control,reaching up to 8.13 g/L,157.15 μg/g,and 1277.63 μg/L,respectively.Furthermore,it was found that in the process of two-stage culture,the adventitious roots grew thicker significantly after they were transferred into production medium directly.Conclusion The ultimate yield of periplocin in P.sepium adventitious root cultures could be significantly increased by a two-stage culture based on nitrogen source.

Contribution of atmospheric nitrogen deposition to diffuse pollution in a typical hilly red soil catchment in southern China

Atmospheric nitrogen （hi） deposition is currently high and meanwhile diffuse N pollution is also serious in China. The correlation between N deposition and riverine N export and the contribution of N deposition to riverine N export were investigated in a typical hilly red soil catchment in southern China over a two-year period. N deposition was as high as 26.1 to 55.8 kg N/（ha-yr） across different land uses in the studied catchment, while the riverine N exports ranged from 7.2 to 9.6 kg N/（ha-yr） in the forest sub-catchment and 27.4 to 30.3 kg N/（ha.yr） in the agricultural sub-catchment. The correlations between both wet N deposition and riverine N export and precipitation were highly positive, and so were the correlations between NH-N or NO2-N wet deposition and riverine NH4-N or NO3-N exports except for NH-N in the agricultural sub-catchment, indicating that N deposition contributed to riverine N export. The monthly export coefficients of atmospheric deposited N from land to river in the forest sub-catchment （with a mean of 14%） presented a significant positive correlation With precipitation, while the monthly contributions of atmospheric deposition to riverine N export （with a mean of 18.7% in the agricultural sub-catchment and a mean of 21.0% in the whole catchment） were significantly and negatively correlated with precipitation. The relatively high contribution of N deposition to diffuse N pollution in the catchment suggests that efforts should be done to control anthropogenic reactive N emissions to the atmosphere in hilly red soil regions in southern China.

Zirconium nitride as a highly efficient nitrogen source to synthesize the metal nitride clusterfullerenes

Metal nitride clusterfullerenes(NCFs)have significant applications in molecular electronics,biomedical imaging,and nonlinear optical devices due to their unique structures.However,their wide applications are limited by the production quantity.In this work,the yields of metal nitride clusterfullerenes M3N@C80(M=Y,Sc,Gd)were greatly enhanced by utilizing zirconium nitride(Zr N)as an efficient nitrogen source for the arc-discharge method.Compared with the traditional synthetic route using N2gas as nitrogen source,the Zr N inside graphite tube can be vaporized simultaneously with metal and graphite,and then afford the high concentration of nitrogen atoms in the arc region,which will promote the formation of metal nitride clusterfullerenes finally.The Zr N can promote the yields of Y3N@C80,Sc3N@C80and Gd3N@C80,revealing the universal applicability of Zr N as a highly efficient nitrogen source.Specifically,the yield of Sc3N@C80was greatly improved when adding Zr N,and it shows over double yield compared to traditional synthetic route using N2gas.In addition,Zr N can also enhance the yields of paramagnetic azametallofullerene M2@C79N due to the high concentration of nitrogen atoms in the arc region.This new method enhances the production quantity of metal nitride clusterfullerenes and azametallofullerenes,and it will greatly promote the research and application of these molecular carbon materials.

Effect of nitrogen and extraction method on algae lipid yield

Effects of nitrogen source and concentration as well as lipid extraction method on the lipid yield of autotrophic Scenedesmus dimorphus and heterotrophic Chlorella protothecoides were studied.Three concentration levels of nitrate,urea and glycine/yeast extract as the nitrogen source were investigated.The highest lipid yield of S.dimorphus in the 17-d autotrophic culture was 0.40 g/L from the 1.8 g/L urea medium,and the maximum lipid yield of C.protothecoides in the nine-day heterotrophic culture was 5.89 g/L from the 2.4 g/L nitrate medium.Four different cell disruption methods-bead-beater,French press,sonication and wet milling-were studied for their effectiveness in solvent extraction of algal lipids from S.dimorphus and C.protothecoides.Wet milling followed by hexane extraction was most effective for S.dimorphus lipid extraction,whereas bead-beater disruption followed by hexane extraction was best for C.protothecoides.

Wastewater-nitrogen removal using polylactic acid/starch as carbon source： Optimization of operating parameters using response surface methodology

Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid （PLA）/ starch blends as carbon source and carrier for fimctional bacteria. The exclusive and interactive influences of operating parameters （i.e., temperature, pH, stirring rate, and PLA-to-starch ratio （PLA proportion）） on nitrification （Y1）, denitrification （Y2）, and COD release rates （Y3） were investigated through response surface methodology. Experimental results indicated that nitrogen removal could be successfully achieved in the PLA/starch blends through simultaneous mtnncatlon anti clenltnncatlon. The carbon release rate of the blends was controllable. The sensitivity of Y1, Y2, and Y3 to different operating parameters also differed. The sequence for each response was as follows： for Y1, pH 〉 stirring rate 〉 PLA proportion 〉 temperature; for Y2, PH 〉 PLA proportion 〉.temperature.〉 stirring rate; and for Y3, stirring rate 〉pH 〉 PLA proportion 〉 temperature. In this study, the following optimum conditions were observed： temperature, 32.0℃; pH 7.7; stirring rate, 200.0 r · min^-1 and PLA proportion 0.4. Under these conditions Y1 Y2 and Y3 were 134.0 μg-N·g-blend^-1·h^-1, 160.9μg-N-g-blend^-1·h^-1, and 7.6 × 10^3 μg-O·g-blend^-1·h^-1, respectively. These results suggested that the PLA/starch blends may be an ideal packing material for nitrogen removal.

CONCENTRATIONS AND FLUXES OF DISSOLVED NUTRIENTS IN THE YANGTZE RIVER: LONG-TERM TRENDS AND ECOLOGICAL IMPACTS

Intensifying human activity in the Yangtze River Basin(YRB) has substantially increased nutrient concentrations in the Yangtze River Estuary,leading to degradation of the coastal environment.Analysis of nutrient determinations published over the past 50 years reveals a gradual decreasing trend in the concentrations and fluxes of dissolved silicate(DSi).However,both dissolved inorganic nitrogen(DIN) and dissolved inorganic phosphate(DIP) concentrations have increased significantly since the 1970 s.The frequency and area covered by red tide outbreaks have increased greatly during this period,mainly due to changes in nutrient supply ratios [i.e.,N/P(DIN/DIP),N/Si(DIN/DSi),P/Si(DIP/DSi)].A strong correlation was found between the riverine DIN fluxes and the estimated DIN inputs from the major N sources,particularly fertilizers and atmospheric deposition.The data provide a comprehensive assessment of nutrients in the YRB and their ecological impacts and indicate a potentially significant influence of atmospheric deposition on DIN loadings and fluxes.

Isolation and Characterization of Methanethiol-Producing Bacteria from Agricultural Soils

Methanethiol(MT) produced from terrestrial soils can have important effects on atmospheric chemistry and ecosystem-level processes, and it originates mainly from the metabolism of sulfur-containing amino acids by microorganisms.Methanethiol producing bacteria(MPB) were enriched and isolated from agricultural soils in a modified basal medium containing methionine(Met) as the sole carbon source.The isolates were identified as Bacillus sp.WH-R1, WH-R2, and WH-R3; Arthrobacter sp.SZLB-W3; and Delftia sp.CHZG-R4 based on cell morphology, physiological and biochemical characteristics, and 16 S r RNA sequence analysis.Delftia sp.CHZG-R4 was identified as a novel strain producing MT using Met as a precursor, and it had the most active MT-producing potential, with the production of MT being 21.8 μg at 30℃ and pH 7.0.Optimal MT production was observed at 35℃ and pH6.0, with 51.3% of sulfur content in Met being converted into MT.Under these conditions, MT production changed according to the supply of both carbon and nitrogen sources.The addition of 2 g L^(-1) each of starch, sucrose, urea, and potassium nitrate promoted MT production by more than 10%, whereas addition of 2 g L^(-1) each of ammonia sulfate and peptone decreased MT production by16% and 87%, respectively.This is the first study to report MT production by Delftia sp.CHZG-R4, providing useful information for the microbial mechanism of MT production from agricultural soils.Our findings also contribute to improving our knowledge of the function of Delftia sp.CHZG-R4.