转Bt水稻土壤微生物多样性对O3浓度升高的响应

利用中国农田开放式O3 浓度升高(O3-FACE)平台,于2010年和2011年对O3浓度升高和田间自然条件下转Bt基因水稻Bt汕优63(Bt-SY63)及其常规水稻汕优63(SY63)根际土壤微生物群落功能多样性进行了研究.结果表明, O3浓度升高使Bt-SY63和SY63水稻土壤微生物总体活性有降低的趋势, O3浓度升高未使两基因型水稻土壤微生物的丰富度、优势度和均一度发生显著变化. O3浓度升高显著地改变了Bt-SY63土壤微生物碳源基质的利用方式,使其土壤微生物由对糖类及其衍生物具有较强的利用能力转向对代谢中产物和次生代谢物具有较强的利用能力,而对SY63土壤微生物碳源基质的利用没有显著影响.因此,从稻田土壤微生物群落对O3浓度升高的不同响应来看,Bt-SY63可能比SY63更敏感.     

原始红松林退化演替后土壤微生物功能多样性的变化

为了全面了解原始红松林退化演替为次生林后土壤生境及土壤微生物功能多样性的变化规律,以小兴安岭典型的原始阔叶红松林、退化演替后先锋阶段的白桦林及亚顶级阶段的硬阔叶林为研究对象,采用Biolog-ECO微平板检测法,分析三者0~ < 10 cm和10~20 cm表层土的土壤微生物功能多样性变化规律.结果表明:各林型土壤微生物的AWCD值（平均颜色变化率）随培养时间的延长而增加,培养初期表现为原始阔叶红松林>硬阔叶林>白桦林;培养末期表现为原始阔叶红松林>白桦林>硬阔叶林,三者的AWCD值在0~ < 10 cm土层分别为1.06、0.86、0.81,10~20 cm土层分别为0.68、0.47、0.45,原始林显著高于次生林（P < 0.05）,说明原始林土壤微生物对单一碳源的代谢活性显著高于次生林;同一林型下土壤微生物的AWCD值均表现为0~ < 10 cm土层显著高于10~20 cm土层（P < 0.05）. Shannon-Wiener多样性指数、Simpson指数、McIntosh指数和Richness丰富度指数也均表现为原始林显著高于次生林（P < 0.05）.原始林土壤微生物对各类碳源的综合利用强度均大于次生林,不同林型下土壤微生物群落的优势碳源类型存在一定的差异,碳水类、氨基酸类、羧酸类和多聚物类碳源是原始林退化演替后土壤微生物群落在碳源利用上发生变化的敏感碳源.      

复垦红壤中牧草根际微生物群落功能多样性

通过盆栽试验研究了浙江省诸暨铜矿区复垦红壤牧草根际微生物生物量及群落功能多样性的变化.结果表明,种植不同牧草使矿区土壤根际微生物生物量碳发生了显著的变化,其影响大小因矿区土壤污染程度而异.无污染和轻度污染土壤根际微生物生物量碳变化表现为黑麦草+三叶草>三叶草>黑麦草>未种植土壤,处理间差异均达显著水平(P<0.05),重度污染环境下各处理间差异不明显.Biolog数据分析显示,种植不同牧草的矿区土壤根际微生物群落结构和功能多样性也发生了相应改变,根际土壤微生物群落代谢剖面(AWCD)均显著高于未种植牧草土壤,处理间差异达极显著水平(P<0.001).典型变量分析揭示了不同牧草根际微生物群落利用碳源种类和数量存在明显差异.     

Microencapsulated chlorpyrifos: Degradation in soil and influence on soil microbial community structures

Degradation kinetics of microencapsulated chlorpyrifos （CPF-MC） in soil and its influence on soil microbial community structures were investigated by comparing with emulsifiable concentration of chlorpyrifos （CPF-EC） in laboratory. The residual periods of CPF-MC with fortification levels of 5 and 20 mg/kg reached 120 days in soil, both of the degradation curves did not fit the first-order model, and out-capsule residues of chlorpyrifos in soil were maintained at 1.76 （±0.33） and 5.92 （±1.20） mg/kg in the period between 15 and 60 days, respectively. The degradation kinetics of CPF-EC fit the first-order model, and the residual periods of 5 and 20 mg/kg treatments were 60 days. Bacterial community structures in soil treated with two concentrations of CPF-MC showed similarity to those of the control during the test period, as seen in the band number and relative intensities of the individual band on DGGE gels （p 〉 0.05）. Fungal community structures were slightly affected in the 5 mg/kg treatments and returned to the control levels after 30 days, but initially differed significantly from control in the 20 mg/kg treatments （p 〈 0.05） and did not recover to control levels until 90 days later. The CPF-EC significantly altered microbial community structures （p 〈 0.05） and effects did not disappear until 240 days later. The results indicated that the microcapsule technology prolonged the residue periods of chlorpyrifos in soil whereas it decreased its side-effects on soil microbes as compared with the emulsifiable concentration formulation.     

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.     

Degradation of chlorpyrifos alone and in combination with chlorothalonil and their effects on soil microbial populations

In practice, pesticides are usually applied simultaneously or one after another for crop protection, and this type of pesticide application often leads to a combined contamination of pesticide residues in the soil environment. A laboratory study was conducted to investigate the influence of chlorothalonil on chlorpyrifos degradation and its effects on soil bacterial, fungal, and actinomycete populations. Under the experimental conditions here, the half-lives of chlorpyrifos alone, and in combination with chlorothalonil, at the recommended and double dosages, were measured to be 3.24, 2.77, and 2.63 d, respectively. Chlorpyrifos degradation was not significantly altered by its combination with chlorothalonil. However, the inhibitory effect of chlorpyrifos on soil microorganisms was increased by its combination with chlorothalonil, and the increase was related to the levels of chlorothalonil added. Compared to those in the controls, the populations of bacteria, fungi, and actinomycetes were significantly reduced by 44.1%, 61.1%, and 72.8%, respectively, on the first day after treatment (DAT) by chlorpyrifos alone. With the addition of chlorothalonil, the inhibition was increased to 55.2%, 79.3%, and 85.8% at the recommended dosage, and 86.0%, 94.1%, and 90.8% at the double dosage, at one DAT, respectively. The results suggested that combined effects should be taken into account to assess the actual impacts of pesticide applications.     

黑龙江中央站黑嘴松鸡国家级自然保护区不同森林类型土壤微生物功能多样性分析

土壤微生物在森林生态系统中起着重要作用,因此研究不同森林类型下土壤微生物功能多样性具有重要意义.采用Biolog-Eco微平板法对位于黑龙江中央站黑嘴松鸡国家级自然保护区内的3种典型森林类型——白桦林、蒙古栎林、兴安落叶松林下的土壤微生物功能多样性进行研究.结果表明:白桦林、蒙古栎林、兴安落叶松林土壤微生物AWCD（平均颜色变化率）值、Shannon-Wiener指数和McIntosh指数差异显著（P < 0.05）.AWCD随着培养时间的延长而逐渐增加,其中白桦林的AWCD值最高,而落叶松林的AWCD值最低.主成分分析（PCA）结果表明,3种森林类型土壤微生物群落代谢功能差异显著,主成分1和主成分2分别可以解释方差变量的38.81%和30.30%.从碳源利用率来看,糖类和氨基酸类是影响3种森林类型土壤微生物功能的主要碳源.典型相关分析（CCA）表明,w（SOC）（SOC为土壤有机质）、w（TN）（TN为全氮）和pH是影响土壤微生物功能多样性的主要环境因子.研究显示,3种森林类型土壤微生物功能多样性和碳源利用方式均有显著差异,其主要受到土壤pH、w（SOC）和w（TN）的影响.      

不同湿地植物脱氮效果与根际土壤微生物群落功能多样性特征分析

为研究水平潜流型人工湿地中不同植物脱氮效果及对土壤微生物的影响,采集水样测定脱氮效率,采集芦苇根际土壤、香蒲根际土壤和对照土壤（不种植物）,利用Biolog技术研究不同处理土壤微生物群落代谢功能多样性特征.结果表明:①与对照相比,种植芦苇和香蒲可提高水平潜流型人工湿地7%~33%的NH₃-N去除率.②芦苇和香蒲根际土壤的碳源利用率增加,并显著高于对照土壤;香蒲根际土壤的碳源利用率高于芦苇根际土壤.芦苇和香蒲根际土壤微生物均对碳水化合物的相对利用率较高（> 48.0%）,对照土壤微生物对碳水化合物和聚合物的相对利用率均较高,分别为34.4%和32.7%.③芦苇和香蒲根际土壤微生物的丰富度指数、Shannon-Wiener多样性指数和Shannon-Wiener均匀度指数均显著高于对照土壤.④主成分分析（principal component analysis,PCA）结果表明,芦苇和香蒲根际土壤微生物与对照土壤微生物对碳源的利用特征均存在显著差异,而不同植物对土壤微生物碳源利用多样性的影响较小.研究显示,种植植物可改善水平潜流型人工湿地的脱氮效率,增加根际土壤微生物群落功能多样性,而不同植物（芦苇和香蒲）对脱氮效率和根际土壤微生物群落组成的影响无显著差异,因此在种植植物时可根据当地条件进行选择.      

黄土区侵蚀坡面土壤微生物群落功能多样性研究

为研究不同有机碳水平下坡面土壤侵蚀对微生物群落功能多样性的影响,以黄土区典型侵蚀坡面为对象,通过Biolog-Eco方法测定了高、低2个有机碳水平坡面沉积区、侵蚀区和对照区3个不同部位的土壤微生物活性、碳源利用能力和微生物群落功能多样性.结果表明：1）高碳水平下3个部位的微生物活性和碳源利用能力均显著高于低碳水平;2）在不同侵蚀部位上,沉积区微生物活性高于侵蚀区,在低碳水平下,沉积区微生物碳源利用能力显著大于侵蚀区（P<0.05）,但在高碳水平下沉积区与侵蚀区无显著差异;3）在6类碳源中,微生物对氨基酸类、酯类的利用率最高,对醇类、胺类的利用率较低,从31种碳源中提取的主成分1和主成分2分别可解释变量方差的53.8%和11.9%,对主成分1起分异作用的主要是氨基酸类和酯类碳源;对主成分2起分异作用的主要为糖类和酸类碳源.4）高碳水平下3个部位微生物群落的Shannon指数、丰富度指数和McIntosh指数均显著大于低碳水平（P<0.05）,但不同部位间的土壤微生物群落多样性指数并无明显差异.侵蚀对微生物群落功能多样性的影响主要表现在有机碳水平决定的微生物活性差别上,不同部位微生物的碳源利用能力在有机碳水平较低时差异显著,有机碳水平较高时则没有明显差别.     

水分调控下旱地土壤中毒死蜱的消解研究

为探讨水分调控下旱地土壤中毒死蜱的消解特性,通过盆栽试验及通径分析方法,研究了不同水分条件下旱地土壤中毒死蜱消解速率及其与土壤性质之间的关系.结果表明:①土壤中毒死蜱的消解速率随时间的延长而逐渐减缓,并且不同水分条件下土壤中毒死蜱的消解速率不同,施药45 d后,5个水分处理（20% FC、40% FC、60% FC、80% FC和100% FC,表示田间持水量依次为20%、40%、60%、80%和100%）下毒死蜱的消解率分别为65.58%~85.56%、70.71%~89.64%、76.30%~95.33%、72.53%~97.60%和70.57%~90.80%,其中以80% FC下的消解速率最快,60% FC下次之.②一级动力学方程能较好地描述土壤中毒死蜱的消解过程（R2>0.88）,消解速率常数（k）最大为0.099 0 d-1.③土壤中毒死蜱的消解速率与w（有机碳）、w（DOC）（DOC为可溶性有机碳）和w（MBC）（MBC为微生物量碳）均呈显著相关.通径分析结果显示,水分条件的改变致使土壤中w（有机碳）、w（DOC）和w（MBC）发生变化,进而对土壤中毒死蜱的消解速率产生较大影响.④大豆、玉米和小麦根际土壤中毒死蜱消解速率均快于非根际土壤,根际土壤中毒死蜱消解速率表现为大豆土壤（0.099 0 d-1）>玉米土壤（0.080 6 d-1）>小麦土壤（0.069 6 d-1）.研究显示,改变土壤水分含量可有效调节土壤中毒死蜱的消解,并为农业生产中毒死蜱的安全施用提供参考依据.      

High starter phosphorus fertilization facilitates soil phosphorus turnover by romoting microbial functional interaction in an arable soil

Microbial phosphorus (P) turnover is critical in C utilization efficiency in agroecosystems. It is therefore necessary to understand the P mobilization processes occurring during P fertilization in order to ensure both crop yield and environmental quality. Here, we established a controlled pot experiment containing soil amended with three different levels of starter P fertilizer and collected soil samples after 30, 60, and 90 days of incubation. Quantitative microbial element cycling (QMEC) smart chip technology and 16S rRNA gene sequencing were used to investigate functional gene structures involved in carbon, nitrogen and P cycling and the bacterial community composition of the collected samples. Although P fertilization did not significantly affect the structure of the soil microbial community, some rare microbiota were changed in particular phosphorus-solubilizing bacteria were enriched at the high P fertilization level, suggesting that the rare taxa make an important contribution to P turnover. P fertilization also altered the functional gene structure, and high P concentrations enhanced the functional gene diversity and abundance. Partial redundancy analysis further revealed that changes in rare taxa and functional genes of soil microorganisms drive the alteration of soil P pools. These findings extend our understanding of the microbial mechanisms of P turnover.     

微生物多样性对土壤碳代谢特征的影响

土壤微生物群落在生态系统过程中发挥着重要的作用,而关于土壤微生物多样性对生态系统功能的影响无一致结论.为了研究微生物多样性对土壤碳代谢特征的影响,将稀释10~(-1)、10~(-3)和10~(-5)倍(D1、D3和D5)的庞泉沟阔叶混交林土壤悬浮液接种在灭菌的土样中.通过碱式滴定法和Biolog Eco板等实验方法测定了不同多样性梯度下土壤碳矿化速率和碳代谢利用模式的变化.结果表明培养6周后,D1处理的碳矿化速率、累积碳矿化量、平均孔颜色变化率(AWCD)和多样性指数(Shannon、Mc Intosh和丰富度指数)均显著高于D5处理.且相关分析表明,累积碳矿化量和AWCD与丰富度呈显著负相关.对碳源吸光度做主成分分析(PCA)和单因素方差分析发现微生物多样性梯度的土壤碳源利用模式也存在差异.因此,微生物多样性下降影响土壤的碳矿化速率和碳源利用模式,导致陆地生态系统的功能发生改变,在森林土壤管理中,应重视土壤微生物物种多样性变化对生态系统功能的影响.     

内蒙古河套灌区不同盐碱程度的土壤细菌群落多样性

采用变性梯度凝胶电泳(DGGE)技术对内蒙古河套灌区三种不同盐碱程度土壤(盐土,强度盐化土,轻度盐化土)不同深度(0~20cm和20~30cm)土壤细菌16S rDNA V3~V6可变区扩增片段进行分析,并对土壤理化性质进行了测定.结果表明:细菌群落多样性随土壤盐碱化程度的加深而减少(轻度盐化土 > 强度盐化土 > 盐土),随土壤深度的增加而降低(细菌群落多样性0~20cm土层大于20~30cm土层).细菌Shannon-Wiener指数在轻度盐化土中最大为3.36,在强度盐化土和盐土分别为3.05和2.49.不同盐碱程度土壤以细菌相似系数聚类,分为0~20cm层与20~30cm层两大族群,土壤细菌群落Shannon-Wiener指数在0~20cm层中(盐土为3.04,强度盐化土为3.29,轻度盐化土为3.36)均大于在20~30cm层(盐土为2.49,强度盐化土为3.05,轻度盐化土为3.14).相关性分析和典范对应分析表明,土壤w(EC)、pH值、w(SOC)、w(TP)是土壤细菌群落结构多样性的显著影响因素,不同盐碱程度土壤中细菌群落的Shannon-Wiener指数与土壤w(EC)(r=-0.542,P < 0.05)、pH(r=-0.526,P < 0.05)呈显著负相关,与土壤w(SOC)(r=0.700,P < 0.01)和w(TP)(r=0.805,P < 0.01)呈极显著正相关.w(EC)和pH对盐碱土壤细菌群落结构的影响力最大. 回收DGGE图谱中20个优势条带进行测序分析,结果显示,变形菌纲(α-变形菌纲、β-变形菌纲、γ-变形菌纲和δ-变形菌纲)是盐碱土壤的主要类群.     

陇东黄土高原石油污染土壤环境因子对金盏菊(Calendula officinalis)-微生物联合修复的响应

为筛选适合陇东黄土高原石油污染土壤修复植物,选取当地"适生"植物金盏菊(Calendula officinalis)联合微生物菌剂开展了为期5个月的原位修复实验.采用常规方法和PCR-DGGE技术分析了修复过程中土壤理化性质、酶活性及土壤微生物群落遗传多样性等15项土壤环境因子的动态变化情况及其对金盏菊生态修复的响应.结果表明,随着原位修复的进行,1土壤脲酶、多酚氧化酶、过氧化氢酶及脱氢酶活性均不同程度呈增加的趋势(p0.05).2土壤TPHs、p H、有机质、含盐率的变化情况不尽相同,但总体呈下降的趋势(p0.05);土壤碱解氮、速效磷及速效钾含量总体呈上升趋势(p0.05).3土壤微生物群落遗传多样性结果显示,Shannon-Wiener多样性指数和Pielou均匀度指数整体呈逐步增加的趋势.4PCA分析结果显示,土壤脲酶、脱氢酶及碱解氮等环境因子对金盏菊修复表现为促进作用,而有机质含量过高将不利于金盏菊的植物修复.金盏菊和微生物菌剂联合修复过程中,土壤多酚氧化酶、速效磷、脱氢酶及速效钾发挥主要作用,而土壤TPHs和含盐率过高则影响了联合修复效果.本研究旨在分析金盏菊用于陇东地区油污土壤的生态响应,结果有助于筛选出适合陇东黄土高原土壤类别-适生植物-土著降解菌群的组合,利用乡土物种的适生性降低修复成本,为陇东地区油污土壤生态修复提供新的技术方案和背景资料.     

生物炭复合青霉菌修复砷污染土壤对其微生物群落功能多样性的影响

真菌修复砷污染土壤是一种能够有效吸附固化环境中砷的重要措施.生物炭作为目前修复重金属的热点,其多空疏松的结构、较高的离子交换量、丰富的有机碳含量等都说明了其在土壤修复中的地位.为了探究生物炭与青霉菌在修复砷污染土壤的同时对土壤中微生物活性及其多样性的影响,在室内孵育条件下,运用Biolog法研究了3×3随机区组试验（3个生物炭梯度分别为0%、2%、4%,3个青霉菌梯度分别为0%、10%、20%）下土壤微生物对不同类型碳源的利用能力以及多种功能性指数的影响.结果表明:①添加青霉菌与生物炭后,土壤中有效砷含量较对照组显著下降,从而影响其微生物群落功能多样性.②砷污染土壤中微生物群落功能多样性、碳源利用丰富度随生物炭浓度梯度的升高呈先升后降的趋势.③高接菌量（20%）与低接菌量（10%）对砷污染土壤中微生物群落功能多样性的影响没有显著性差异.④2%生物炭与10%青霉菌处理土壤中微生物群落功能多样性、碳源利用丰度最高.⑤青霉菌对胺类及少部分酸类碳源的利用能力较弱（AWCD < 0.5,AWCD为Biolog微平板孔中溶液吸光值平均颜色变化率）,对氨基酸类中大部分碳源以及脂类碳源的代谢能力较强（AWCD>1.0）,对糖类、酚酸类的代谢能力稍弱（AWCD为0.3~1.0）,青霉菌对D-半乳糖醛酸、L-天冬酰胺酸、L-丝氨酸、L-精氨酸、r-羟基丁酸这5种碳源的利用率最高（AWCD>1.2）.研究显示,低浓度生物炭可增加砷污染土壤中微生物群落多样性,生物炭含量的继续增加会对微生物产生抑制作用;青霉菌添加到砷污染土壤后,会显著提升砷污染土壤中微生物的群落功能多样性,改善砷污染土壤中微生的物群落结构;青霉菌的优势碳源大多为植物根系分泌物,可为后续青霉菌与超积累植物复合修复砷污染土壤提供参考.      

除草剂硝磺草酮对土壤微生物生态效应研究

采用室内培养试验,研究了硝磺草酮对土壤酶活性和微生物群落功能多样性的影响.结果表明,土壤过氧化氢酶和蔗糖酶活性随硝磺草酮浓度增加呈现先增加后降低的趋势,但比对照处理都有所升高,分别增加了22.6%~41.0%和3.4%~54.2%,且在硝磺草酮浓度为50mg/kg时达到最大.与之相反,尿酶活性则降低了12.0%~18.6%,但差异性不明显(P > 0.05).施用一定浓度的硝磺草酮激活了土壤微生物活性,微生物群落丰富度、均匀性和多样性都呈增长趋势,单孔的平均颜色变化率(AWCD)值和利用速率均随硝磺草酮浓度增加而增大,微生物群落对碳水化合物类、氨基酸类、多聚物类、羧酸类、胺类和酚酸类利用率整体上均有所提高,与对照相比,最大增幅分别达到5.3、1.0、4.4、3.2、0.2和6.8倍,但不同浓度硝磺草酮处理下土壤微生物在利用碳源的类型上是存在一定的差异.     

基于旱地土壤环境风险的农药毒死蜱的施用限值研究

通过开展田间试验,研究毒死蜱在玉米、小麦和大豆3种作物田土壤中的降解及环境风险,基于毒死蜱及其降解产物TCP的残留特征和环境风险,计算毒死蜱施用限值.研究表明玉米田土壤中的毒死蜱残留量大于大豆田和小麦田;毒死蜱在农田土壤中的降解速率随着施用浓度的增加而提高.小麦、大豆、玉米3种作物种植土壤中毒死蜱及TCP的短期和长期生态风险均有差异.玉米、大豆和小麦3种作物农田中,当超过推荐剂量施用毒死蜱,毒死蜱及TCP均具有较高短期风险和长期生态风险,相对于毒死蜱,TCP对土壤的生态风险更高.基于旱地土壤的毒死蜱及TCP的环境风险,通过模型计算农药毒死蜱在大豆田中的施用限值为0.4412 kg·hm^-2,在小麦田中的施用限值为0.5034 kg·hm^-2,在玉米田中的施用限值为0.5487 kg·hm^-2.     

Effects of combination of plant and microorganism on degradation of simazine in soil

The degradative characteristics of simazine （SIM）, microbial biomass carbon, plate counts of heterotrophic bacteria and most probably number （MPN） of SIM degraders in uninoculated non-rhizosphere soil, uninoculated rhizosphere soil, inoculated non- rhizosphere soil, and inoculated rhizosphere soil were measured. At the initial concentration of 20 mg SIM/kg soil, the half-lives of SIM in the four treated soils were measured to be 73.0, 52.9, 16.9, and 7.8 d, respectively, and corresponding kinetic data fitted first-order kinetics. The experimental results indicated that higher degradation rates of SIM were observed in rhizosphere soils, especially in inoculated rhizosphere soil. The degradative characteristics of SIM were closely related to microbial process. Vegetation could enhance the magnitude of rhizosphere microbial communities, microbial biomass content, and heterotrophic bacterial community, but did little to influence those community components responsible for SIM degradation. This suggested that rhizosphere soil inoculated with microorganisms-degrading target herbicides was a useful pathway to achieve rapid degradation of the herbicides 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.     

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.