Formation of volatile sulfur compounds by microbial decomposition of sulfur-containing amino acids in soils

Evolution of volatile sulfur compounds from soils treated with S-containing amino acids was studied by sensitive gas chromatographic techniques involving use of a flame photometric detector fitted with a sulfur filter. The following volatile sulfur compounds were identified as products of microbial decomposition of S-containing amino acids in soils under aerobic or waterlogged conditions: methyl mercaptan, dimethyl sulfide and dimethyl disulfide (evolved from soils treated with methionine, methionine sulfoxide, methionine sulfone or S-methyl cysteine); ethyl mercaptan, ethyl methyl sulfide and diethyl disulfide (evolved from soils treated with ethionine or S-ethyl cysteine); and carbon disulfide (evolved from soils treated with cystine, cysteine, lanthionine or djenkolic acid). Small amounts of dimethyl sulfide and carbon disulfide were evolved from soils treated with homocystine, and trace amounts of carbonyl sulfide were evolved from soils treated with lanthionine or djenkolic acid. No volatile sulfur compounds were evolved from soils treated with cysteic acid, taurine, or S-methyl methionine. The amounts of sulfur volatilized from soils treated with the 14 S-containing amino acids studied represented from less than 0·1 per cent to more than 50 per cent of the sulfur added as amino acid. Hydrogen sulfide could not be detected as a gaseous product of microbial decomposition of S-containing amino acids in soils under aerobic or waterlogged conditions.     

Evolution of volatile sulfur compounds from soils treated with sulfur-containing organic materials

Release of volatile S compounds from soils treated with S-containing organic materials was studied by sensitive gas chromatographic techniques. Methyl mercaptan, dimethyl sulfide, dimethyl disulfide, carbonyl sulfide and carbon disulfide were identified as gaseous products of decomposition of animal manures, sewage sludges and plant materials in soils under aerobic or waterlogged conditions. No release of hydrogen sulfide was detected. Most of the S volatilized from soils treated with sludges was in the form of dimethyl sulfide and dimethyl disulfide. whereas most of the S volatilized from soils treated with manures and plant materials was in the form of methyl mercaptan and dimethyl sulfide. More S compounds were released, and more S was volatilized, by decomposition of manures, sludges or plant materials in soils under waterlogged conditions than by decomposition under aerobic conditions. When calculated as a percentage of the S added as organic material, the average amount of S volatilized under aerobic or waterlogged conditions was < 0.2% < 0.5% and < 3.4% for the sludges, manures and plant materials, respectively. The five volatile S compounds produced by decomposition of manures, sludges and plant materials in soils under aerobic and waterlogged conditions also were produced by decomposition of plant proteins (zein, gluten and gliadin). It is concluded that the volatile S compounds released by decomposition of the above organic materials in soils are largely, if not entirely, produced by microbial degradation of methionine and cystine in these materials.     

Inhibition of nitrification in soil by heterocyclic nitrogen compounds

Summary The relationship between the structures of diverse heterocyclic nitrogen (N) compounds and the effectiveness of these compounds for the inhibition of nitrification in soil was studied by determining the effects of different amounts of 12 unsubstituted and 33 substituted heterocyclic N compounds on the production of (NO ₂ ^– +NO ₃ ^– )-N in soils incubated at 25 °C for 21 days after treatment with ammonium sulfate. The results showed that unsubstituted heterocyclic N compounds containing two adjacent ring N atoms inhibit nitrification in soil and that two of these compounds, pyrazole and 1,2,4-triazole, are potent inhibitors. They also showed that several substituted pyrazoles and thiadiazoles are good inhibitors of nitrification in soil (e.g., 3-methylpyrazole and 3,4-dichloro-1,2,5-thiadiazole).     

Analysis of sulfur compounds in acid sulfate soils and other recent marine soils

Abstract

A refined scheme for the semi micro chemical analysis of sulfur fractions in soils is presented. Pyrite is analyzed, as iron, after extraction in HNO₃. Non‐pyrite iron is excluded by a pretreatment with HF/H₂SO₄. Water‐soluble sulfate and jarosite [KFe₃(SO₄)₂(OH)₆], the other dominant sulfur fractions in acid sulfate soils, are analyzed turbidimetrically, as sulfate, after successive extractions by EDTA.3Na (water soluble plus exchangeable SO₄) and by hot 4 M HCl (jarosite). These methods are simpler, less bulky and more specific than most existing procedures.

Introduction of elemental sulfur analysis permits estimation of organic sulfur fraction as well. Sums of individual sulfur fractions agree well with separate total sulfur determinations.

The proposed analysis of pyrite permits also distinction of the components Fe₂O₃, FeO and FeS₂ in soils and rocks².     

Inhibition of nitrification in soil by gaseous hydrocarbons

Summary Recent work has shown that gaseous hydrocarbons such as methane, ethane, and ethylene are competitive inhibitors of the monooxygenase enzyme responsible for oxidation of ammonia by chemoautotrophic nitrifying microorganisms such as Nitrosomonas europaea. Because methane, ethane, and ethylene are produced by microbial activity in soil, we studied the possibility that they may inhibit oxidation of ammonia by the nitrifying soil microorganisms. We found that all three of these gaseous hydrocarbons inhibited nitrification in soil and that their ability to inhibit nitrification decreased in the order: ethylene > ethane > methane. Ethylene was much more effective than ethane or methane for inhibiting nitrification of ammonium in soil, but it was much less effective than acetylene, and it seems unlikely that the amounts of ethylene produced in soils will be sufficient to cause significant inhibition of nitrification by soil microorganisms.     

Effects of food materials on removal of Allium-specific volatile sulfur compounds

Effects of food materials were investigated on removal of several kinds of thiols, sulfides, and disulfides, which arise from vegetables of Allium species during food preparation and eating. Methanethiol, propanethiol, and 2-propenethiol were captured by raw foods such as fruits, vegetables, and mushrooms or a mixture of their acetone powders and phenolic compounds. The odor of diallyl disulfide was remarkably reduced by kiwi fruit, spinach, cutting lettuce, parsley, basil, mushrooms, and, particularly, cow's milk, raw egg, boiled rice, and bovine serum albumin (BSA). This suggests that the removal of diallyl disulfide could be caused by a physical and chemical interaction between the disulfide and foods. Furthermore, milk and BSA captured propanethiol, 2-propenethiol, dipropyl sulfide, diallyl sulfide, dimethyl disulfide, and dipropyl disulfide very well. An enzymatic degradation of diallyl disulfide by spinach and asparagus was also observed. These results demonstrate that the deodorization with foods is achieved by multiple actions including physical and chemical interaction between volatile sulfur compounds and foods, enzymatic degradation of disulfides, and addition of thiols to polyphenolic compounds, catalyzed by polyphenol oxidases or peroxidases.     

Sorption of sulfur gases by soils

Gas Chromatographie studies showed that air-dry and moist soils have the capacity to sorb dimethyl sulfide (CH₃SCH₃), dimethyl disulfide (CH₃SSCH₃). carbonyl sulfide (COS) and carbon disulfide (CS₂), but do not sorb sulfur hexafluoride (SF₆). Moist soils sorb larger amounts of CH₃SCH₃. CH₃SSCH₃. COS or CS₂, than do air-dry soils, but the capacity of moist (or air-dry) soils for Sorption of these gases is much smaller than their capacity for sorption of H₂S. SO₂ or CH₃SH. The ability of moist soils to sorb COS is considerably greater than their ability to sorb CH₃SCH₃, CH₃SSCH₃ or CS₂. and sorption of COS by moist soils is accompanied by release of small amounts of CS₂.Experiments with sterilized (autoclaved) soils indicated that soil microorganisms are partly responsible for the sorption of CH₃SCH₃. CH₃SSCH₃. COS and CS₂ by moist soils. Support for this conclusion was obtained from experiments showing that the rate of sorption of these gases by moist soils increases with time.The work reported provides further evidence that soil is an important natural sink for gaseous atmospheric pollutants, but indicates that soils have little, if any, potential value for removal of CH₃SCH₃. CH₃SSCH₃. COS or CS₂, from industrial emissions polluted by these gases. The finding that soils have no capacity for sorption of SF₆ is significant in relation to use of this gas as a tracer for atmospheric research and as an internal standard for gas Chromatographie studies of evolution and sorption of gases by soils.     

硝化作用驱动下红壤渗漏液的酸化

土壤渗漏液pH对于亚热带酸性土壤的物质迁移和溶液中物质形态具有重要影响。为了研究亚热带酸性土壤硝化作用释放H+与渗漏液pH的关系,以具有不同硝化强度的3个红壤样本为供试材料,分别加入铵态氮0、150和300 mg kg-1,进行112 d的室内土柱模拟淋溶实验。结果表明:酸性土壤的渗漏液并不一定呈酸性。土壤渗漏液pH取决于硝化作用产生H+的速率与土壤酸缓冲能力的综合作用。当硝化作用使渗漏液中NO3-浓度升高至一定程度时,渗漏液pH突然下降,这一临界NO3-浓度与土壤盐基饱和度及加入土壤的铵态氮量呈线性正相关(p0.05)。所以,硝化作用最强的旱地土壤,由于其盐基饱和度达81%,渗漏液始终保持中性;而硝化作用不强、盐基饱和度为21%的灌丛土壤,其渗漏液pH可降至4.0以下。     

Characterization of sulfur retained by soils exposed to sulfur dioxide

Abstract

Soils have substantial capacity for sorption of sulfur dioxide (SO₂) but little is known about the nature of the sorbed S. Three surface soils varying in pH, organic matter, CaCO₃ equivalent and surface area were exposed to air containing 5% SO₂ and subsequently analyzed by ten different procedures to characterize the sorbed S. Most of the sulfur retained by soils after exposure to SO₂ could be recovered as CaCl₂‐extractable S, Ca(H₂PO₄)₂‐extractable S, or S released as H₂S by hydriodic acid (HI). Only small amounts of sulfur could be recovered as tetrachloromercurate (TCM)‐extractable S, S released as SO₂ by HCl, or S released as H₂S by HCl + Zn, HCl + Sn, or Raney Ni and NaOH. However, large amounts of S released as SO₂ by HCl were recovered from the air‐dry Webster and the moist Storden soils indicating that SO₂ sorption is influenced by organic matter in air‐dry soils and by CaCO₃ in moist soils.     

Effect of temperature on nitrification in soils

Nitrification plays an important role in nitrogen transformation in soils. As a practical problem the fact is noteworthy that by nitrification, the loss of nitrogen from soils is caused at higher temperatures in the summer. On the contrary, it is quite slow at the lower temperatures of early spring. Recently much Work has been done on the effect of temperature on nitrification in soils. It was noticed that its effect is not the same according to the difference of soils. Soils which have high nitrifying activities at ordinary temperatures (around 25°C) show fairly good nitrification even at lower temperatures (1, 2, 5). However, in nitrification by usual experimental methods, the amount of nitrate produced can be only estimated while nitrifying organisms are increasing or decreasing in soil. As the growing Process of microbes is extremely influenced by both the properties of the soil and the cultural conditions, it is necessary to examine the effect of temperature on the growing process of microbes rather than biochemical nitrification by a unit cell. In usual methods nitrification can hardly be treated in these separate aspects. The author has succeeded in obtaining soils in which nitrifying organisms increase to the maximum limit, and no increase can be expected in number of these organisms. By using such samples, experiments were made concerning the effect of temperature on nitrification by a unit cell and its direct effect on the growth of organisms. Furthermore, the author prepared favorable cultural conditions for various kinds of soils by the “washing cultivation method” (6), and examined the effect of temperature on the increasing process of nitrifying ability.     

Effect of cropping systems on nitrification in soils

Abstract

Limited information is available about the effect of cropping systems and N application on nitrification potential of soils. This study was conducted to evaluate nitrification rates of soils that have been under long‐term cropping systems at three sites in Iowa. Each experiment consisted of three cropping systems (continuous corn, corn‐soybean‐corn‐soybean, and corn‐oats‐meadow‐meadow) and two fertilizer treatments: untreated (0 N) and treated (+ N) with ammonium or ammonium‐forming fertilizers (180 or 200 kg ha/yr) before corn. The rate of nitrification was studied at 30°C. Results showed that, although soil pH decreased in the plots treated with ammoniacal fertilizers before corn in the cropping system, the rate of nitrification was significantly greater in N‐treated than in untreated plots, suggesting that fertilization with ammonium or ammonium‐forming fertilizers either increased the microbial populations responsible for nitrification in soils and/or that such treatments increased the efficiency of the nitrifiers by inducing the enzymes responsible for conversion of NH⁴⁺ to NO₃‐. The results suggest that continuous application of ammonium or ammonium‐forming fertilizer could enhance the nitrification rate and increase the potential of contamination of groundwater with nitrate.     

Effects of urease inhibitors on nitrification in soils

The effects of 10 urease inhibitors on nitrification in soils were studied by determining the effects of 10 and 50 parts/10⁶ (soil basis) of each inhibitor on the amounts of nitrate and nitrite produced when soils treated with ammonium sulfate (200 μg of ammonium N/g of soil) were incubated (30°C) under aerobic conditions for 14 days. The urease inhibitors used (catechol. hydroquinone, p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2,5-dimethyl-p-benzoquinone. 2,6-dimethyl-p-benzoquinone. 2,5-dichloro-p-benzoquinone, 2,6-dichloro-p-benzoquinone. sodium p-chloromercuribenzoate, and phenylmercuric acetate) were those found most effective in previous work to evaluate more than 130 compounds as soil urease inhibitors. Their effects on nitrification were compared with those of three compounds patented as soil nitrification inhibitors (N-Serve. AM. and ST).Most of the urease inhibitors studied had little effect on nitrification when applied at the rate of 10 μg/g of soil. but had marked inhibitory effects when applied at the rate of 50 μg/g of soil. None inhibited nitrification as effectively as N-Serve. but phenylmercuric acetate inhibited nitrification more effectively than did AM or ST when applied at the rate of 10 μg/g of soil. Phenylmercuric acetate, 2,5-dimethyl-p-benzoquinone, and 2,6-dimethyl-p-benzoquinone had very marked effects on nitrification when applied at the rate of 50 μg/g of soil.     

Growth of comammox Nitrospira is inhibited by nitrification inhibitors in agricultural soils

Purpose

The discovery of comammox Nitrospira being capable of complete oxidising ammonia to nitrate radically challenged the conventional concept of two-step nitrification. However, the response of comammox Nitrospira to nitrification inhibitors (NIs) and their role in soil nitrification remain largely unknown, which has hindered our ability to predict the efficiency of NIs in agroecosystems.

Materials and methods

We evaluated the effect of four NIs, 2-chloro-6-(trichloromethyl) pyridine (nitrapyrin), 3,4-dimethylpyrazole phosphate (DMPP), allylthiourea (ATU) and dicyandiamide (DCD) on the growth of comammox Nitrospira, ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) in two pasture and arable soils.

Results and discussion

The amendment of nitrogen fertiliser significantly increased soil nitrate concentrations over time, indicating a sustaining nitrification activity in both soils. The addition of all the four NIs effectively reduced the production of nitrate in both soils, but to varying degrees during incubation. The abundances of comammox Nitrospira clade A were significantly increased by addition of nitrogen fertilisers and significantly impeded by the four NIs in the pasture soil, but their abundances were only remarkably hindered by nitrapyrin in the arable soil. All the four NIs obviously inhibited the AOB abundances in both soils. Except for DMPP, the other three NIs effectively suppressed the AOA abundances in both soils.

Conclusions

We provided new evidence that growth of comammox Nitrospira clade A can be stimulated by nitrogen fertilisers and inhibited by various nitrification inhibitors, suggesting their potential role in nitrification of agricultural soils.

     

几种吡啶类化合物对土壤硝化的抑制作用比较

为了探明吡啶类化合物对土壤硝化作用的抑制效应,采用室内微宇宙试验,研究了2-氯-6(三氯甲基)硫酸盐、2-氯-6(三氯甲基)盐酸盐、吡啶混合物和吡啶X类化合物对潮土、红壤和水稻土中铵态氮硝化的抑制作用。结果表明,在35 d培养期内,吡啶类化合物处理土壤硝态氮含量明显低于对照(未添加吡啶类化合物),吡啶类化合物对土壤中铵态氮的硝化抑制率介于2.91%~91.92%,抑制强度先逐渐升高后降低,在培养21 d时抑制强度达到峰值。不同类型吡啶类化合物对土壤中铵态氮的硝化抑制效果存在差异,吡啶盐酸盐类化合物优于其他几类化合物;吡啶类化合物对土壤中铵态氮的硝化抑制作用与土壤类型有关,对3种土壤中铵态氮的硝化抑制作用表现为潮土>水稻土>红壤。就同一土壤而言,硝化抑制强度随着吡啶类化合物用量的增加而增加。     

Heterotrophic nitrification by sodium chloride-tolerant fungi in soils added with sodium chloride

Abstract

Recently, fungi with the ability of heterotrophic nitrification have been isolated from acid forest soils (Lang and Jagnow 1986; Stroo et al. 1986). It is suggested that under unsuitable conditions for autotrophic nitrification, heterotrophic processes for NO₂ ^- and NO_{3 -} production could be advantageous.     

Mineralization and nitrification in three Malaysian forest soils

Examination of three forest soils from Malaysia using the soil incubation technique suggests that nitrification was not inhibited in these oligotrophic soils. Nitrification rates were between 40 and 750 ngN produced g^?1 dry weight soil day^?1 of incubation. Addition of phenolic metabolites (tannic acid) and leaf filtrates from hill and lowland forest litter did not significantly inhibit nitrification. Addition of sucrose (1% w/w carbon source) decreased nitrification but not ammonification.     

Effects of organic manure on nitrification in arable soils

Summary The production of nitrate by the process of nitrification is highly dependent on other N-transforming processes in the soil. Hence, changes in the type of N compound applied to enrich agricultural soils may affect the production of nitrate. The size and activity of the chemolithotrophic bacterial community were studied in an integrated farming system, with increased inputs of organic manure and reduced inputs of mineral nitrogenous fertilizer, versus conventional farming. The integrated farming had a positive effect on potential nitrifying activity, but not on the numbers of chemolithotrophic nitrifying bacteria as determined by a most probable number technique or by fluorescence antibody microscopy. Cells of the recently described nitrite-oxidizing species Nitrobacter hamburgensis and Nitrobacter vulgaris were just as common as the cells of the well known species Nitrobacter winogradskyi. It was concluded that nitrification is stimulated by integrated farming, presumably by an increased mineralization of ammonium which is not immediately consumed by the crop or immobilized in the heterotrophic microflora of the soil. Since nitrifying bacteria are involved in the production of NO and N₂O, integrated farming with the application of manure may favour the production of noxious N-oxides.Communication no. 40 of the Dutch Programme on Soil Ecology of Arable Farming Systems     

pH regulates key players of nitrification in paddy soils

Increasing lines of evidence have suggested the functional importance of ammonia-oxidizing archaea (AOA) rather than bacteria (AOB) for nitrification in upland soils with low pH. However, it remains unclear whether niche specialization of AOA and AOB occurs in rice paddy wetlands constrained by oxygen availability. Using DNA-based stable isotope probing, we conclude that AOA dominated nitrification activity in acidic paddy soils (pH 5.6) while AOB dominated in alkaline soils (pH 8.2). Nitrification activity was stimulated by urea fertilization and accompanied by a significant increase of AOA in acid soils and AOB in alkaline soils. DNA-based stable isotope probing indicated significant assimilation of ¹³CO₂ for AOA only in acidic paddy soil, while AOB was the solely responsible for ammonia oxidation in the alkaline paddy soil. Phylogenetic analysis further indicated that AOA members within the soil group 1.1b lineage dominated nitrification in acid soils. Ammonia oxidation in the alkaline soil was catalyzed by Nitrosospira cluster 3-like AOB, suggesting that the physiological diversity of AOA is more complicated than previously thought, and soil pH plays important roles in shaping the community structures of ammonia oxidizers in paddy field.     

红壤氮素的矿化和硝化作用特征

采用培养试验研究了侵蚀红壤,培肥后的红壤以及不同利用方式红壤氮素的矿化和硝化作用特征.结果表明,侵蚀红壤的矿化作用和硝化作用都很微弱,采用适宜的施肥措施培肥后氮素的矿化和硝化速率都有很大提高;红壤氮素的矿化和硝化速率与土壤pH、速效磷含量和有机质含量呈显著正相关.     

New cysteine-S-conjugate precursors of volatile sulfur compounds in bell peppers (Capsicum annuum L. cultivar)

The objective of this study was to verify whether the volatile organic sulfur compounds recently discovered in bell pepper (Capsicum annuum, L. cultivars), such as the mercapto-ketones: 4-sulfanyl-2-heptanone and 2-sulfanyl-4-heptanone, the mercapto-alcohols: 4-sulfanyl-2-heptanol and 2-sulfanyl-4-heptanol, and heptane-2,4-dithiol, originate from their corresponding cysteine-S-conjugates. Analysis of aqueous extracts of red and green bell pepper by ultraperformance liquid chromatography-mass spectrometry with electrospray ionization in the positive mode (UPLC-MS ESI(+)) displayed masses corresponding to the expected cysteine-S-conjugates. To confirm this observation, four cysteine-S-conjugates were prepared as authentic samples: S-(3-hydroxy-1-methylhexyl)-L-cysteine, S-(3-hydroxy-1-propylbutyl)-L-cysteine, S-(3-oxo-1-propylbutyl)-L-cysteine, and (2R,2'R)-3,3'-(4-hydroxyheptane-2,6-diyl)bis(sulfanediyl) bis(2-aminopropanoic acid). By comparison with the fragmentation patterns and retention times of synthetic mixtures of cysteine-S-conjugate diastereoisomers, the natural occurrence of cysteine conjugates was confirmed in bell peppers. In addition, the cysteine-S-conjugates from red and green bell pepper extracts were concentrated by ion exchange chromatography and the fractions incubated with a β-lyase (apotryptophanase). The liberated thiols were concentrated by affinity chromatography, and their occurrence, detected by gas chromatography-mass spectrometry, confirmed our predictions. Moreover, 3-sulfanyl-1-hexanol was also detected and the occurrence of S-(1(2-hydroxyethyl)butyl)-L-cysteine confirmed. A quantitative estimation based on external calibration curves, established by UPLC-MS ESI(+) in selected reaction monitoring mode, showed that cysteine-S-conjugates were present at concentrations in the range of 1 to 100 μg/kg (±20%).