Copper pollution decreases the resistance of soil microbial community to subsequent dry–rewetting disturbance

Dry–rewetting(DW) disturbance frequently occurs in soils due to rainfall and irrigation, and the frequency of DW cycles might exert significant influences on soil microbial communities and their mediated functions. However, how microorganisms respond to DW alternations in soils with a history of heavy metal pollution remains largely unknown.Here, soil laboratory microcosms were constructed to explore the impacts of ten DW cycles on the soil microbial communities in two contrasting soils(fluvo-aquic soil and red soil)under three copper concentrations(zero, medium and high). Results showed that the fluctuations of substrate induced respiration(SIR) decreased with repeated cycles of DW alternation. Furthermore, the resistance values of substrate induced respiration(RS-SIR)were highest in non-copper-stressed(zero) soils. Structural equation model(SEM) analysis ascertained that the shifts of bacterial communities determined the changes of RS-SIR in both soils. The rate of bacterial community variance was significantly lower in noncopper-stressed soil compared to the other two copper-stressed(medium and high) soils,which might lead to the higher RS-SIR in the fluvo-aquic soil. As for the red soil, the substantial increase of the dominant group WPS-2 after DW disturbance might result in the low RS-SIR in the high copper-stressed soil. Moreover, in both soils, the bacterial diversity was highest in non-copper-stressed soils. Our results revealed that initial copper stress could decrease the resistance of soil microbial community structure and function to subsequent DW disturbance.     

喀斯特高原退化湿地草海土壤微生物群落碳源代谢活性研究

为了揭示土壤微生物群落功能多样性对湿地退化过程的响应及其与环境因子的关系,采用BIOLOG-ECO微平板法对喀斯特高原湿地草海不同植被演替阶段根际土壤微生物的碳源代谢活性进行了研究.结果表明,沿湿地植被演替梯度,根际土壤微生物群落碳源代谢强度逐渐增加,原生湿地竹叶眼子菜(Comm.Potamogeton malaianu)根际土壤微生物碳源利用能力最低,碳源代谢类型单一;草甸灯芯草(Juncus effusus L.)群落利用能力最强,碳源代谢类型丰富;Shannon指数(H')和Mc Intosh指数(U)均沿植被演替梯度逐渐升高,这可能与地上植物和土壤理化环境变化有关;主成分分析(PCA)提取的3个主成分累计贡献率为92.85%,能够很好解释不同阶段碳源利用的分异,醇类和氨基酸类是引起碳源利用分异的主要基质;冗余分析(RDA)表明,环境因子对微生物碳源代谢活性具有重要影响,p H、DOC是引起碳源利用分异的主要环境因子.土壤微生物群落碳源代谢活性影响湿地碳循环功能.     

稻草还田对土壤微生物群落功能多样性的影响

为了探讨稻草还田的微生物学过程与效应,借助平板涂抹法和BIOLOG检测法,比较研究了免耕条件下3种不同稻草还田量(33%、67%和100%,以稻草不还田土壤为对照)对晚稻田土壤微生物群落功能多样性的影响.结果表明:①土壤细菌数量差异显著,以67%稻草还田处理为最高,稻草不还田处理最低,稻草还田提高了土壤细菌数量;②碳源平均颜色变化率(AWCD法)在培养早期各处理间的差异不大,但随着培养时间的延长,67%和100%稻草还田处理土壤微生物的AWCD值显著大于对照和33%稻草还田处理组;③土壤微生物代谢多样性指数(丰富度和多样性)在3种稻草还田量处理土壤中也表现出明显差异,67%和100%稻草还田处理的土壤中微生物功能多样性显著大于33%稻草还田处理和对照;④67%和100%稻草还田处理显著改善了土壤微生物的功能多样性.以67%稻草还田处理改善土壤微生物群落结构和功能的效果最为显著.     

Soil resource availability impacts microbial response to organic carbon and inorganic nitrogen inputs

Impacts of newly added organic carbon （C） and inorganic nitrogen （N） on the microbial utilization of soil organic matter are important in determining the future C balance of terrestrial ecosystems. We examined microbial responses to cellulose and ammonium nitrate additions in three soils with very different C and N availability. These soils included an organic soil（ 14.2% total organic C, with extremely high extractable N and low labile C）, a forest soi1（4.7% total organic C, with high labile C and extremely low extractable N）, and a grassland soil（1.6% total organic C, with low extractable N and labile C）. While cellulose addition alone significantly enhanced microbial respiration and biomass C and N in the organic and grassland soils, it accelerated only the microbial respiration in the highly-N limited forest soil. These results indicated that when N was not limited, C addition enhanced soil respiration by stimulating both microbial growth and their metabolic activity, New C inputs lead to elevated C release in all three soils, and the magnitude of the enhancement was higher in the organic and grassland soils than the forest soil. The addition of cellulose plus N to the forest and grassland soils initially increased the microbial biomass and respiration rates, but decreased the rates as time progressed. Compared to cellulose addition alone, cellulose plus N additions increased the total C-released in the grassland soil, but not in the forest soil. The enhancement of total C- released induced by C and N addition was less than 50% of the added-C in the forest soil after 96 d of incubation, in contrast to 87.5% and 89.0% in the organic and grassland soils. These results indicate that indigenous soil C and N availability substantially impacts the allocation of organic C for microbial biomass growth and/or respiration, potentially regulating the turnover rates of the new organic C inputs.     

Structural and metabolic responses of microbial community to sewage-borne chlorpyrifos in constructed wetlands

Long-term use of chlorpyrifos poses a potential threat to the environment that cannot be ignored, yet little is known about the succession of substrate microbial communities in constructed wetlands(CWs) under chlorpyrifos stress. Six pilot-scale CW systems receiving artificial wastewater containing 1 mg/L chlorpyrifos were established to investigate the effects of chlorpyrifos and wetland vegetation on the microbial metabolism pattern of carbon sources and community structure, using BIOLOG and denaturing gradient gel electrophoresis(DGGE) approaches. Based on our samples, BIOLOG showed that Shannon diversity(HV) and richness(S) values distinctly increased after 30 days when chlorpyrifos was added. At the same time, differences between the vegetated and the non-vegetated systems disappeared. DGGE profiles indicated that H Vand S had no significant differences among four different treatments. The effect of chlorpyrifos on the microbial community was mainly reflected at the physiological level. Principal component analysis(PCA) of both BIOLOG and DGGE showed that added chlorpyrifos made a difference on test results.Meanwhile, there was no difference between the vegetation and no-vegetation treatments after addition of chlorpyrifos at the physiological level. Moreover, the vegetation had no significant effect on the microbial community at the genetic level. Comparisons were made between bacteria in this experiment and other known chlorpyrifos-degrading bacteria. The potential chlorpyrifos-degrading ability of bacteria in situ may be considerable.     

老化油泥处理过程中的微生物群落变化特征

通过在油田现场构建2个中试规模的生物堆(秸秆添加堆和对照堆)对老化油泥进行处理,运用BIOLOGTM系统对油泥中微生物群落水平的生理特性进行分析,测定其微生物代谢活性、代谢多样性及代谢特征差异性,以研究堆体各层次间微生物群落代谢特征的变化规律. 结果表明,与对照堆相比,秸秆添加堆的多项生理特性指标均得到显著提升,其中微生物代谢多样性指数变化范围由1.64～3.02升至2.83～3.29,并且表现出时间上的稳定性和空间层次间的均质性;在微生物碳源代谢特征的差异性分析中,对照堆各层次随时间推移表现出向其外层顺次变化的规律;油泥中总异养菌及石油烃降解菌的数量与环境温度关联性较强,石油烃降解菌的数量在试验末期取得峰值,达4.15×107 CFU/g.      

乙草胺与硫酸铜对黑土微生物的复合生态影响

为了探究2种不同类型农药联合施用对土壤微生物的复合生态影响,以除草剂乙草胺和杀菌剂硫酸铜为例,采用传统毒理学方法和BIOLOG法对其进行评价.结果表明,乙草胺和硫酸铜的联合施用对细菌、放线菌和真菌活菌量以及土壤脱氢酶活性基本呈现急性抑制效应,但随时间延长其作用逐渐减弱甚至发生逆转,而对土壤底物诱导呼吸强度表现为明显促进.利用Shannon、Simpson和McIntosh多样性指数模型和主成分分析法对BIOLOG数据进行分析,表明2种农药的联合施用显著破坏了黑土微生物群落物种多样性的丰富度和均一性,主成分分析法也表明土壤微生物群落碳源利用多样性发生了改变.     

不同相伴阴离子对镉污染红壤微生物区系及群落功能多样性的影响

通过外加醋酸镉和氯化镉的室内培养试验研究了不同相伴阴离子对镉污染红壤中微生物区系及群落功能多样性的影响 .结果表明 :在相同镉浓度下相伴OAc-对镉污染红壤的细菌、放线菌和真菌数量及微生物群落功能多样性的抑制作用大于相伴Cl-.统计分析显示 ,在供试红壤中OAc-与Cl-对其微生物区系及微生物群落代谢剖面 (AWCD值 )、Shannon指数的影响均达到显著差异 (P <0 0 5 ) ,且在红砂土上表现更为明显 .外加醋酸钾和氯化钾的培养试验结果表明 ,阳离子为钾时 ,相伴OAc-与Cl-对红壤微生物区系结构及群落功能多样性没有产生明显抑制作用 ,相伴OAc-甚至存在一定的刺激作用 .可见 ,相伴OAc-对镉污染红壤微生物的毒害作用大于相伴Cl-,其原因并非是阴离子本身的毒性效应 ,而镉的生物有效性变化可能是不同相伴阴离子镉盐导致毒性差异的原因之一 .     

Bacterial diversity in soils around a lead and zinc mine

Five samples of soil collected from a lead and zinc mine were used to assess the effect of combined contamination of heavy metals on soil bacterial communities using a polyphasic approach including characterization of isolates by culture method, community level catabolic profiling in BIOLOG GN microplates, and genetic community fingerprinting by denaturing gradient gel electrophoresis of 16S rDNA fragments amplified by PCR from community DNA （PCR-DGGE）. The structure of the bacterial community was affected to a certain extent by heavy metals. The PCR-DGGE analysis of 16S rRNA genes showed that there were significant differences in the structure of the microbial community among the soil samples, which were related to the contamination levels. The number of bacteria and the number of denaturing gradient gel electrophoresis （DGGE） bands in the soils increased with increasing distance from the lead and zinc mine tailing, whereas the concentration of lead （Pb） and cadmium （Cd） was decreased. Heavily polluted soils could be characterized by a community that differs from those of lightly polluted soils in richness and structure of dominating bacterial populations. The clustering analysis of the DGGE profiles showed that the bacteria in all the five samples of soil belonged to three clusters. The data from the BIOLOG analysis also showed the same result. This study showed that heavy metal contamination decreased both the biomass and diversity of the bacterial community in soil.     

Effect of heavy metals on soil microbial activity and diversity in a reclaimed mining wasteland of red soil area

The microbial biomass, basal respiration and substrate utilization pattern in copper mining wasteland of red soil area, southern China, were investigated. The results indicated that soil microflora were obviously different compared with that of the non-mine soil. Microbial biomass and basal respiration were negatively affected by the elevated heavy metal levels. Two important microbial ecophysiological parameters, namely, the ratio of microbial biomass C（ Cmic ）/organic C（ Corg ） and metabolic quotient（qCO2 ） were closely correlated to heavy metal stress. There was a significant decrease in the Cmic/Corg ratio and an increase in the metabolic quotient with increasing metal concentration. Multivariate analysis of Biolog data for sole carbon source utilization pattern demonstrated that heavy metal pollution had a significant impact on microbial community structure and functional diversity. All the results showed that soil microbiological parameters had great potential to become the early sensitive, effective and liable indicators of the stresses or perturbations in soils of mining ecosystems.     

邻苯二甲酸酯对土壤微生物群落多样性的影响

邻苯二甲酸酯（PAEs）是存在最广泛的有机有毒污染物之一.利用BIOLOG和ARDRA方法,分别考察了不同浓度PAEs对土壤微生物代谢多样性和遗传多样性的影响.结果表明,不同浓度PAEs处理的土壤的平均颜色变化率（AWCD）值随时间增加的幅度不同,PAEs浓度越高、AWCD值增幅越小,对微生物代谢活性的抑制作用越大;不同浓度PAEs处理样品中微生物群落生理代谢活性和碳代谢类群表现出明显差异,空白和低浓度土壤微生物以糖类和羧酸类代谢群为优势类群,而中浓度和高浓度土壤微生物以多胺类代谢群为优势类群;主成分分析也显示碳代谢类型出现差异,PC1就能将4个样品很好地分开,与PC1正相关程度较高的碳源有L-天冬酰胺酸、 4-羟基苯甲酸和D-苹果酸,负相关的碳源有D-半乳糖醛酸、i-赤藻糖醇、γ-羟基丁酸和1-磷酸葡萄糖.ARDRA带型分析表明不同的土壤样品的多样性指数随着PAEs浓度的增加而增加,短时间内PAEs能增加土壤微生物群落的代谢多样性.     

Biochemical and microbial soil functioning after application of the insecticide imidacloprid

Imidacloprid is one of the most commonly used insecticides in agricultural practice, and its application poses a potential risk for soil microorganisms. The objective of this study was to assess whether changes in the structure of the soil microbial community after imidacloprid application at the field rate (FR, 1 mg/kg soil) and 10 times the FR (10× FR, 10 mg/kg soil) may also have an impact on biochemical and microbial soil functioning. The obtained data showed a negative effect by imidacloprid applied at the FR dosage for substrate-induced respiration (SIR), the number of total bacteria, dehydrogenase (DHA), both phosphatases (PHOS-H and PHOS-OH), and urease (URE) at the beginning of the experiment. In 10× FR treated soil, decreased activity of SIR, DHA, PHOS-OH and PHOS-H was observed over the experimental period. Nitrifying and N₂-fixing bacteria were the most sensitive to imidacloprid. The concentration of NO₃^- decreased in both imidacloprid-treated soils, whereas the concentration of NH₄⁺ in soil with 10× FR was higher than in the control. Analysis of the bacterial growth strategy revealed that imidacloprid affected the r- or K-type bacterial classes as indicated also by the decreased eco-physiological (EP) index. Imidacloprid affected the physiological state of culturable bacteria and caused a reduction in the rate of colony formation as well as a prolonged time for growth. Principal component analysis showed that imidacloprid application significantly shifted the measured parameters, and the application of imidacloprid may pose a potential risk to the biochemical and microbial activity of soils.     

Monitoring impact of mefenacet treatment on soil microbial communities by PCR-DGGE fingerprinting and conventional testing procedures

The effect of acetanilide herbicide mefenacet on soil microbial communities was studied using paddy soil samples with different short-term treatments. The culturable bacteria （plate counts）, dehydrogenase activity and changes in community structure （denaturing gradient gel electrophoresis （DGGE） analysis） were used for biological community assessments. Mefenacet was a significant stimulus to cultural aerobic bacteria and dehydrogenase activity while Sphingobacterium multivorum Y1, a bacterium efficiently degrading the mefenacet, only induced the increasing colony-forming unit （CFU） of bacteria but little effect on dehydrogenase activity during the whole experiment. The degree of similarity between the 16S rDNA profiles of the communities was quantified by numerically analyzing the DGGE band patterns. Similarity dendrograms showed that the microbial community structures of the mefenacet-treated and non-treated soils were not significantly different. But supplement of S. multivorum Y1 could increase the diversity of the microbial community in the mefenacet-polluted paddy soil. This work is a new attempt to apply the S. multivorum Y1 for remediation of the mefenacet-polluted environments.     

Effect of lime application on microbial community in acidic tea orchard soils in comparison with those in wasteland and forest soils

Lime application is a conventional technology to control acidification in tea orchard soils. We investigated the e ect of lime application on soil microbial community diversity in the soils of three tea orchards, wasteland and forest. The BIOLOG data showed that both the average well color development of all carbon sources and the functional diversity index increased with the liming rate in the tea orchards and the forest, but decreased in the wasteland. The phospholipid fatty acid (PLFA) analysis showed that the structural diversity index of soil microbial community increased with the liming rate in all the tea orchards, the wasteland and the forest. Lime application also increased the soil-bacterial PLFA content in all the soils. Soil fungal and actinomycete PLFAs in the tea orchards showed an increasing trend from 0 to 3.2 g CaCO3/kg application and then a decreasing trend from 3.2 to 6.4 g CaCO3/kg application. The principal component analysis of BIOLOG and PLFA data suggested that lime application had a significant e ect on soil microbial community structure, and land use had a greater e ect on soil microbial community structure compared to lime application.     

微生物群落对土壤微生物呼吸速率及其温度敏感性的影响

通过灭菌和重新接种不同土壤微生物群落的方法,探索了改变土壤微生物群落对土壤微生物呼吸速率及其温度敏感性的影响.结果表明,灭菌海伦黑土接种未灭菌的哈尔滨黑土、封丘潮土和祁阳红壤后,15℃时土壤CO2的累积释放量分别为684.25、753.97和644.91μg,25℃时土壤CO2的累积释放量分别为963.06、1 015.44和852.31μg,35℃时土壤CO2的累积释放量分别为1 252.55、380.36和1 177.88μg;土壤CO2的累积释放量随接种剂土壤pH增加而增加,而与接种剂土壤有机质含量高低、接种剂土壤与被接种土壤的地理距离无关.15、25和35℃时,接种不同微生物群落的土壤呼吸速率表现差异的持续时间分别为104、277和1 177 h,差异持续时间随培养温度增高而延长.接种未灭菌的哈尔滨黑土、封丘潮土和祁阳红壤后,土壤呼吸温度敏感性指数Q10在0～104 h分别为1.63、1.49和1.80,在0～277 h分别为1.43、1.39和1.46,在0～1 609 h分别为1.35、1.35和1.35;呼吸温度敏感性随接种剂土壤pH降低而增加,随培养时间延长而减小.本研究表明改变土壤微生物群落将影响土壤微生物呼吸速率及其温度敏感性.     

Lead toxicity thresholds in 17 Chinese soils based on substrate-induced nitrification assay

The influence of soil properties on toxicity threshold values for Pb toward soil microbial processes is poorly recognized. The impact of leaching on the Pb threshold has not been assessed systematically. Lead toxicity was screened in 17 Chinese soils using a substrate-induced nitrification (SIN) assay under both leached and unleached conditions. The effective concentration of added Pb causing 50% inhibition (EC50) ranged from 185 to > 2515 mg/kg soil for leached soil and 130 to > 2490 mg/kg soil for unleached soil. These results represented > 13- and > 19-fold variations among leached and unleached soils, respectively. Leaching significantly reduced Pb toxicity for 70% of both alkaline and acidic soils tested, with an average leaching factor of 3.0. Soil pH and CEC were the two most useful predictors of Pb toxicity in soils, explaining over 90% of variance in the unleached EC50 value. The relationships established in the present study predicted Pb toxicity within a factor of two of measured values. These relationships between Pb toxicity and soil properties could be used to establish site-specific guidance on Pb toxicity thresholds.     

Quantification of the effects of management factors on maize (Zea mays L.) and cotton (Gossypium hirsutum L.) residues decomposition rate

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Alteration of microbial properties and community structure in soils exposed to napropamide

The effect of pesticide napropamide (N,N-diethyl-2-(1-naphthalenyloxy) propanamide) on soil microorganisms for long-term (56 d) was assessed by monitoring changes in soil microbial biological responses. Soils were treated with napropamide at 0, 2, 10, 20, 40, and 80 mg/kg soil and sampled at intervals of 1, 3, 7, 14, 28, 42, and 56 d. The average microbial biomass C declined in napropamide-treated soils as compared to control. The same trend was observed on microbial biomass N after napropamide application.We also determined the basal soil respiration (BSR) and observed a high level in soils treated with napropamide during the first 7 d of experiment. But with the passage of incubation time, BSR with napropamide decreased relatively to control. Application of napropamide at 2–80 mg/kg soil had inhibitory e ects on the activity of urease and invertase. Activity of catalase was enhanced during the initial 7 d of napropamide application, but soon recovered to the basal level. The depressed enzyme activities might be due to the toxicity of napropamide to the soil microbial populations. To further understand the e ect of napropamide on microbial communities, a PCRDGGE- based experiment and cluster analysis of 16S rDNA community profiles were performed. Our analysis revealed an apparent di erence in bacterial-community composition between the napropamide treatments and control. Addition of napropamide apparently increased the number of bands during the 7–14 d of incubation. These results imply that napropamide-induced toxicity was responsible for the disturbance of the microbial populations in soil.     

不同温度下的土壤微生物呼吸及其与水溶性有机碳和转化酶的关系

为研究不同温度下的土壤微生物呼吸及其与水溶性有机碳(DOC)和转化酶的关系,设置了室内培养实验.采集南京市周边老山、紫金山、宝华山的土壤,研究不同土壤的微生物呼吸对温度升高的响应规律,并分析土壤DOC含量及转化酶活性.结果表明,不同土壤的累积微生物呼吸与土壤温度之间的关系均可用指数方程描述,其P值均达到极显著水平(P0.001),不同地点土壤的微生物呼吸温度敏感系数(Q10值)在1.762~1.895之间变异.累积土壤微生物呼吸的Q10值随着土壤温度升高表现出降低的趋势.培养后27 d土壤微生物呼吸的Q10值与培养后1 d的Q10值无显著差异(P0.05),这表明难分解有机质的温度敏感性与易分解有机质的温度敏感性一致.对于所有土壤而言,累积土壤微生物呼吸与DOC含量之间存在极显著(P=0.003)的线性回归关系,DOC可以解释累积土壤微生物呼吸31.6%的变异性.无论是单独分析不同土壤还是综合所有土壤的测定结果,累积微生物呼吸与土壤转化酶活性均存在极显著(P0.01)的一元线性回归关系,由此说明转化酶活性是衡量土壤微生物呼吸大小的一个较好的指标.     

酸性矿山废水对稻田土壤微生物菌群结构的影响

为探究酸性矿山废水(AMD)对稻田土壤微生物群落结构的影响,通过取自矿区受AMD污染和未受污染的稻田土壤进行微宇宙灌溉模拟实验,研究了AMD污染过程中土壤理化性质和微生物群落的变化,同时建立环境条件变化引起土壤微生物群落结构改变的相关性关系.结果表明,受AMD污染的土壤中SO_4~(2-)、Cd、Zn含量显著上升,土壤酸化且土壤中细菌群落的多样性下降;而恢复清洁水灌溉可提高土壤细菌群落的多样性,有利于修复AMD的污染.采用高通量测序技术分析了不同处理稻田土壤中微生物群落在门和属分类水平上的相对丰度分布变化,冗余分析(RDA)表明,土壤pH和重金属(Pb、Cu)含量是影响稻田土壤微生物群落结构的主要环境因子.研究结果不仅有助于进一步揭示AMD污染、土壤因子与土壤微生物群落的相互关系,同时可为恢复AMD污染农业土壤提供理论依据.