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1.
The sensitivity of soil bacteria towards Pb was investigated. Soil suspensions from fourteen different soil types with a high or low Pb content were plated out on soil extract agar containing various concentrations of PbCl2.In agar with a high Pb content, higher bacterial counts were found with suspensions from Pb-containing soils than with those of soils with a low Pb content. In the Pb-containing soils, proportionally more gram-negative rods were present while coryneform bacteria decreased. In an additional experiment, in which Pb was added to a sandy soil, more Pb-tolerant bacterial strains were found 3 years later than in the same soil without Pb.When pure cultures of the bacteria isolated from the soils were tested in liquid media for Pb tolerance, a higher proportion of tolerant strains was found in Pb-containing soils. Among strains of gram-negative bacteria isolated from these soils a higher proportion of tolerant strains was found than in corneform bacteria.It was concluded that as a consequence of Pb pollution of soil a selection of Pb-tolerant bacteria may take place. 相似文献
2.
The effects of short and long term acidification on a few Alberta soils were studied with respect to bacterial numbers and total soil respiration. Significant reductions in bacterial numbers were observed in both short and long term acidified soils. Total soil activity was severely affected in an acid soil (pH 3.0, longterm) adjacent to a S block. A soil (pH 6.8) 200 m away from this S block when artificially acidified to pH 2.9 significantly reduced soil activity but not as drastically as found in the long term pH 3.0 soil. A garden soil (pH 7.7) which was also acidified to pH 3.2 showed no significant reduction in total soil respiration rate as compared to its unacidified control soil. These acid soils when amended with organic substrates demonstrated that certain physiological groups of organisms were severely inhibited by this acid condition. The importance of examining more than one parameter when assessing the effect of a potential pollutant on soil activity is discussed. 相似文献
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W. Chrishanthi Fernando Kousuke Suyama Kazuhito Itoh Hideyuki Tanaka Hiroki Yamamoto 《Soil Science and Plant Nutrition》2013,59(5):701-709
Degradation of an acylated starch-plastic mulch film was evaluated in two soil types, a gray lowland soil (A) and a volcanic andosol (V). Weight loss, tensile strength (TS) loss and loss of percentage elongation (%E) were measured under laboratory conditions (black and white mulch films), and in the field (black films). Changes in the counts of total bacteria, total fungi, gram-negative bacteria, total Fusarium, ATP (adenosine triphosphate) content, % nitrification, pH (H2O), and total C and total N contents were determined at 4,8, 12, and 20 months in the field test soils where the mulch was repeatedly applied, and compared with controls. Film weight loss was greater in soil V than in soil A in both the laboratory and the field, and the losses were greater in the laboratory than in the field in both soils A and V. Significant TS losses and considerable %E losses were observed. Values were similar in the laboratory and in the field. No significant changes in the counts of bacteria, fungi, gram-negative bacteria, and Fusarium were observed. The ATP content of the test soils increased slightly compared with the initial values. The ATP content in the control soils initially fell, and then increased in response to weeding. Nitrification remained almost unchanged in the test soils, but fell in the control soils until the last sampling. However, the mulch film underwent a definite process of degradation in the soils, with great loss of physical properties and lesser weight loss. This degradation had no adverse impact on the soil microflora. 相似文献
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Background Tetracycline is a widely used antibiotic in animal production. Significant amounts of the substance reach the soil via feces,
urine and manure application. As tetracycline is a persistent compound with antibacterial activity, its presence in soil may
have undesired direct and indirect effects. These have been investigated so far focusing on effects on selected microbial
functions.
Objectives The aim of the present study was to obtain comprehensive information on potential effects of tetracycline on the soil microflora
under environmentally relevant conditions. The investigations included function and structure of the microbial biocoenosis
and the distribution of resistance genes.
Methods Pig manure rich in tetracycline resistance genes was applied to a sandy soil. This soil as well as an unamended soil were
additionally treated with several concentrations of tetracycline. The spiked soils were incubated in outdoor lysimeters for
several months. Substrate induced respiration, PLFAs, ten selected resistance genes, and the concentrations of tetracycline
were determined.
Results The test concentrations, though far exceeding environmental relevance, caused only small effects. An establishment of resistance
could not be detected. Applied resistance genes were not detectable at the end of the study even in the presence of added
tetracycline.
Conclusion Due to the high sorption capacity of the antibiotic, environmentally relevant concentrations of tetracycline do not seem to
cause undesired effects on the soil microflora. 相似文献
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研究菠萝-甘蔗轮作制对甘蔗生长及土壤生态的影响结果表明,菠萝-甘蔗轮作甘蔗产量和糖度均高于甘蔗-甘蔗连作;与连作田相比轮作田可改善土壤通气性和蓄水能力,加速土壤速效养分的释放,增强土壤酶活性和增加土壤微生物总量;有益的氨化细菌和硝化细菌成倍增加,而无益的厌氧性细菌、反硝化细菌则受抑制。 相似文献
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《Communications in Soil Science and Plant Analysis》2012,43(7):629-636
Abstract Tests were conducted to determine the effects of leptophos, phorate, terbufos, and WL 24073 {0‐ [2‐chloro‐1‐(2,5‐dichloro‐phenyl) vinyl] 0‐methylethylphosphonothioate} on microbial populations and activities in a sandy loam. A stimulatory effect on bacterial numbers was observed with some insecticide treatments in the early stages of incubation. WL 24073 increased the nitrification of the incorporated (NH4)2SO4‐N. Phorate stimulated soil microbial respiration. 相似文献
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J. Gonzalez-Lopez M. V. Martinez-Toledo V. Salmeron 《Biology and Fertility of Soils》1992,13(3):173-175
Summary We studied the effects of the organophosphorus insecticide methidathion, at concentrations of 10, 50, 100, 200 and 300 g g-1 in an agricultural soil, on fungi, total bacterial populations, aerobic N2-fixing bacteria, denitrifying bacteria, nitrifying bacteria (phases I and II), and nitrogenase activity (acetylene reduction assay). The presence of 10–300 g g-1 of methidathion significantly increased fungal populations (colony-forming units). Denitrifying bacteria, aerobic N2-fixing bacteria and N2 fixation were significantly increased at concentrations of 50–300 g g-1. The total number of bacteria increased significantly at concentrations of 100–300 g g-1. Nitrifying bacteria decreased initially at concentrations of 300 g g-1, but recovered rapidly to levels similar to those in the control soil without the insecticide. 相似文献
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Summary Every second month for 2 years a beech forest floor was treated with pentachlorophenol and 2,4,5-trichorophenoxyacetic acid each in two concentrations. The microbial biomass and its respiration activity in the three litter horizons were measured during this time and during a recovery period of 2 years after the treatment was stopped. The microbial biomass, mainly fungi, was decreased dose-responsively, as was the respiration rate. The doubling time of the fungal biomass was estimated to be about 50–100 days in the F horizon, and considering the natural decreases and recovery times observed, it is suggested, following Domsch et al. (1983), that a biomass decrease of 75%–93.75% is tolerable, a decrease of less than 75% is negligible, and a decrease of over 93.75% is critical. 相似文献
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为探讨轮作与连作对烟田根际土壤微生物群落的影响,采用实验室微生物培养联合微生物高通量测序技术,分析了玉米-烤烟轮作和烟叶连作对烟株根际土壤微生物数量、群落结构及其多样性的影响。研究结果表明,轮作烟田根际土壤中可培养细菌和放线菌数量均高于连作烟田根际土壤,但真菌数量低于连作烟田。土壤高通量测序结果表明,轮作烟田根际土壤真菌和细菌群落多样性均高于连作烟田;在烟株的生长过程中,轮作和连作烟田在旺长期和成熟期微生物群落相似度降低。相较于黑胫病/根腐病/根结线虫发病率较高(36. 67%)的连作烟田来说,轮作烟田发病率较低(0%),进一步分析真菌和细菌群落结构发现,轮作烟田根际土壤中拮抗菌如Sphingomonas (鞘脂单胞菌属)、Pseudomonas (假单胞菌属)、Aspergillus (曲霉属)等相对丰度均高于连作烟田,而连作烟田根腐病病菌Pythium (腐霉属)丰度较高。 相似文献
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植物内生菌影响土壤微生物区系的研究进展 总被引:1,自引:0,他引:1
土壤微生物区系是土壤生态环境的重要组分,其结构的稳定性对作物的健康生长至关重要。本文重点综述了植物内生菌对土壤微生物区系的调节作用,调节机制及潜在应用,指出了植物内生菌影响土壤微生物区系研究中出现的问题。一些植物内生菌不仅对植物生长有益,还可以显著改善土壤微生物区系,主要表现在对土壤微生物种类及数量、微生物生物量、酶活性及相关酶基因表达的影响,这可能是内生菌在土壤中和植物体内引发的多种效应的综合。植物内生菌可以在土壤中作为腐生菌与土壤微生物存在生态位竞争,通过产生某些抗菌活性物质和有机酸影响土壤微生物生长,通过降解复杂有机物如木质素、酚类化感物质等调节微生物区系,并吸收和转运重金属降低其对土壤微生物区系的危害等等。最后提出了今后的研究方向。 相似文献
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Soil organic matter (SOM) in arctic and boreal soils is the largest terrestrial reservoir of carbon. Increased SOM mineralisation under increased temperature has the potential to induce a massive release of CO2. Precise parameterisation of the response of arctic soils to increased temperatures is therefore crucial for correctly simulating our future climate. Here, we investigated the temperature response of SOM mineralisation in eight arctic soil profiles of Norway, Svalbard and Russia. Samples were collected at two depths from both mineral and organic soils, which were affected or not by permafrost and were incubated for 91 days at 4, 8, 12, and 16 °C. Temperature response was investigated through two parameters derived from a simple exponential model: the intensity of mineralisation, α, and the temperature sensitivity, Q10. For each sample, SOM quality was investigated by 13C-NMR, whereas bacterial and fungal community structure was characterised by T-RFLP and ARISA fingerprints, respectively. When estimated from the whole incubation period, α proved to be higher in deep permafrost samples than in shallow active layer ones due to the presence transient flushes of mineralisation in deep permafrost affected soils. At the end of the incubation period, after mineralization flushes had passed, neither α nor Q10 (averaging 1.28 ± 0.07) seemed to be affected by soil type (organic vs mineral soil), site, depth or permafrost. SOM composition and microbial community structure on the contrary where affected by site and soil type. Our results suggest that deep samples of permafrost affected soil contain a small pool of fast cycling carbon, which is quickly depleted after thawing. Once the mineralization flush had passed, the temperature response of permafrost affected soil proved to be relatively homogenous among sample types, suggesting that the use of a single temperature sensitivity parameter in land surface models for SOM decomposition in permafrost-affected soils is justified. 相似文献
13.
López-Periago JE Arias-Estévez M Soto-González B Trelles-Reinoso S Simal-Gándara J 《Journal of agricultural and food chemistry》2006,54(13):4751-4757
The influence of methanol on the adsorption of the fungicide cyprodinil by a crop soil was studied by equilibrium measurements and by determining the retention-release dynamics in a continuous stirred flow tank reactor (CSTR). Equilibrium measurements showed the effective coefficient of partition of cyprodinil between soil and solution, K(dc), decreases linearly as the concentration of methanol in the solution increases until a percentage of 20% is reached. In CSTR experiments, the retention of cyprodinil was found to be almost reversible; up to a 95% of the fungicide was desorbed. The retention-release dynamics showed biphasic behavior and was partially controlled by diffusion. This behavior was reproduced by a model of diffusion into micropores identifying the soil particles as spheres and taking into account both intraparticle nonlinear adsorption and nonlinear adsorption at external surfaces. In all cases, the sorption kinetics was not the limiting step. The main effect of methanol in the retention-release dynamics ended up being based on the changes produced in the adsorption equilibrium. Methanol also increased the effective diffusion coefficient and decreased the mass transfer coefficient. The optimized Freundlich's isotherm coefficients for <5% methanol were lower than those obtained from the batch experiments. 相似文献
14.
The control mechanisms regulating the utilization of carbohydrates by soil populations were examined. Glucose, fructose, galactose, lactose, cellobiose and xylose were added to the soil either separately or in combination with glucose and the formation and activity of enzymes catabolizing the individual carbohydrates were studied. No specific repression of the formation of carbohydrate-degrading enzyme by glucose was observed in the soil. The activity of galactose-degrading enzymes was inhibited in the presence of glucose, resulting in a sequential utilization of the two sugars. Similarly, the rate of utilization of lactose and, in part, of cellobiose was inhibited in the presence of glucose. The activity, rather than the synthesis, of the enzymes was thus inhibited by glucose; the inhibition was reversible. 相似文献
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亚表层培肥结合覆膜提高干旱区盐碱地土壤肥力及优势菌群丰度的机理 总被引:1,自引:0,他引:1
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Summary The effects of zinc added to a diluvial sandy clay loam soil on its microflora and the metabolic products of amended glucose in the soil were investigated, and its influences on both biological and chemical turnover are discussed.Changes in the soil microflora were followed by counting the microbes and measuring their contributions to soil respiration. The transformations of 14C-glucose products were traced in five divided fractions.Amended glucose was readily assimilated into microbial tissues and transformed to metabolites in the control soil. Within the initial 24 h of the incubation, most of the glucose was decomposed and about 40% of the substrate evolved as carbon dioxide. This primary metabolism was attributed to the bacterial population, and the subsequent secondary metabolism was associated with fungal growth rather thanbacteria. On the other hand, zinc (1000 g/g) added as chloride prolonged the primary metabolism of glucose and a large part of the incubation period for 96 h was occupied by this metabolism, which was mostly dependent on the fungal population. Viable bacterial number noticeably within the first 24 h of the incubation. During the course of the subsequent incubation, however, this number increased and the selection for zinc tolerance was suggested. 相似文献
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不同深度土壤控水对稻田土壤微生物区系及细菌群落多样性的影响 总被引:1,自引:0,他引:1
为研究不同深度土壤控水对壤土稻田土壤水势、微生物区系和细菌群落多样性的影响,通过土培池栽试验,在水稻生育后期设置土壤深度0~5 cm(S05)、0~10 cm(S10)和0~15 cm(S15)控水处理,以保持水层为对照,分析了不同深度控水处理下5 cm、10 cm、15 cm深土壤水势与土壤微生物区系、细菌群落多样性的变化。结果表明:土壤5 cm、10 cm、15 cm深度的水势随着控水深度增加而降低,S05控水处理主要影响上层(5 cm)土壤水势,S10控水处理影响上、中层(10 cm)土壤水势,S15控水处理土壤水势随土层深度的增加而升高。花后8 d和32 d,S05控水处理上层土壤细菌数量显著高于S10、S15控水处理;花后16~24 d,S05控水处理中层、下层(15 cm)土壤细菌数量均显著高于S15控水处理;土壤水势与水稻生育后期中、下层土壤细菌数量呈极显著正相关关系。S05控水处理10 cm、15 cm土层的细菌丰富度Chao指数均显著高于S15控水处理及CK。3个控水处理中,5 cm土层细菌的多样性Shannon指数以S05控水处理最低。优势细菌菌群分析发现,优势群落主要为变形菌门、绿弯菌门、酸杆菌门、拟杆菌门,四者总相对丰度在80%以上;S15控水处理中层土壤变形菌门相对丰度低于S05和S10控水处理。3个控水处理土壤样品中优势纲(相对丰度大于2%)达15个,主要包括α-变形菌纲、β-变形菌纲、δ-变形菌纲、厌氧绳菌纲等,这4个纲的总相对丰度在47%以上,其中厌氧绳菌纲相对丰度最高;上层土壤中S05控水处理的β-变形菌纲相对丰度显著低于S10和S15控水处理。因此,不同深度土壤控水对壤土土壤水势、细菌数量存在影响,改变了细菌的多样性及丰富度,对土壤细菌优势菌种类无显著影响。 相似文献
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The increasing frequency of chemically contaminated groundwater, occurring as a result of improperly managed waste disposal or accidental spills, presents a need for research on the fate of chemical mixtures in the soil. The batch equilibration technique was used to measure adsorption of 14C ring-labeled atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) for a Palouse silt loam (Pachic Ultic Haploxeroll) and a Pembroke silty clay loam (Typic Paleudalf). The solution phase consisted of mixtures of methanol-water and hexane-water containing up to 33.3 % organic solvent by volume. Aqueous solubility limited atrazine concentrations to 100 μmol L?1 except for an additional isotherm determined in 33.3 methanol-water at up to 1542 μmol L?1 The Freundlich adsorption coefficient indicated that the Palouse adsorbed more atrazine than the Pembroke with K values of 4.95 and 0.54, respectively. Both soils showed a significant decrease in K as the percentage methanol increased. Adsorption isotherms from a 33. 3 methanol-water system were of the Freundlich type for atrazine concentrations of 0.25 to 1542 μmol L?1. In the hexane-water systems, K decreased as the fraction of hexane increased and the Pembroke soil adsorbed less atrazine than the Palouse soil. These results suggest that the introduction of nonaqueous solvents such as methanol and hexane decreased adsorption and increased the potential for atrazine mobility. 相似文献
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Samples of a slightly acid sand soil were subjected to frequently repeated cycles of drying (85 or 30°C), moistening and incubation (29°C, 4 weeks). During about 60 cycles the loss of carbon, as CO2, from the samples dried at 85°C, 30°C and the undried ones was found to be 31.2, 18.0 and 17.0%. respectively. A complete depletion of degradable material was not achieved after 60 drying-wetting cycles. After 60 cycles the 85 C-samplcs still showed the highest CO2-production.The microbial population was reduced in numbers and species in all samples. The highest numbers of bacteria and fungi were found in the samples originally dried at 85°C. However, only a relative low proportion of these microorganisms could grow on less easily accessible substrates.Data on changes in the pH and on the C/N ratio of the organic matter are discussed, together with possible ways in which organic matter becomes available during heating. 相似文献