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1.
有机氯农药污染场地危害人体健康及生态系统安全，高活性降解微生物对提升土壤有机氯农药降解效率十分必要。本研究结合高通量测序和荧光定量PCR技术，探究添加分别表达二氯苯降解基因(xylH、dmpB、catE)的质粒pUC19(102～103 copies/μL)和菌群(单独表达上述质粒的大肠杆菌E.coli DH5α,105～106 CFU/μL)后，土壤中1,4-二氯苯降解动力学、微生物群落组成与降解功能演变。研究发现：添加降解基因及菌群210 d后，土壤中1,4-二氯苯降解效率提升1.74倍～2.41倍，最高分别达38.43%和44.74%；优势菌门及关键物种相对丰度占比显著上升(P<0.05)；土著菌群降解基因绝对丰度显著上升了1.24倍～2.89倍，添加降解菌群上升幅度更显著(P<0.05)。本研究有助于探明外源添加降解基因及菌群后土著菌群应对污染胁迫的响应机制，为调控和优化农药污染土壤修复过程及效果提供技术支持。 相似文献
2.
【目的】蚯蚓肠道微生物种类繁多，其中细菌群落对蚯蚓适应不同的生境具有重要作用，而关于蚯蚓肠道菌群的研究多集中于养殖型蚯蚓，野生蚯蚓的研究相对缺乏。【方法】为解析不同生境野生蚯蚓肠道的菌群差异，本研究采集河北省沧州市农林科学院试验田中的黄瓜地和辣椒地的通俗腔蚓（Metaphire vulgaris），并通过高通量测序对其肠道细菌群落进行了分析。提取蚯蚓肠道微生物总DNA，特异性扩增16S rRNA基因的V3-V4区，利用Illumina Hiseq 2500测序平台进行双端测序，然后对OTU(operational taxonomic unit)归类，并进行物种组成分析、Alpha和Beta多样性分析、样品组间统计分析。【结果】蚯蚓肠道分离土样中CZM（采自辣椒地的蚯蚓）和CZH（采自黄瓜地的蚯蚓）相对丰度大于1%的优势菌属分别为12和13个，肠道细菌中门水平相对丰度最高的是变形菌（Proteobacteria）。同时，还发现一些未分类的细菌，CZH肠道菌群中未分类的细菌较多，且CZH肠道细菌多样性指数也高于CZM。此外，CZH和CZM肠道细菌中丰富度位于前30且有属类分析的OTU代表性... 相似文献
3.
石油降解菌的筛选、鉴定及菌群构建 总被引：3，自引：0，他引：3
从胜利油田石油污染土壤中富集、分离得到236株能以石油作为唯一碳源和能源的石油降解菌株；采用选择性培养基进行复筛得到直链烷烃降解菌31株、环烷烃降解菌28株、芳烃降解菌3株以及表面活性剂产生菌24株；从3种不同烃类降解菌和表面活性剂产生菌中选择菌株，构建石油降解微生物菌群，结果表明，由菌株SL-51、SL-84、SL-133和SL-163组成的菌群c9降解石油能力最强，菌群C9在含原油浓度为0．5％的无机盐培养液中，5d内原油的降解率达到了55．5％；气相色谱分析结果证明，菌群C9能有效降解原油中的饱和烃和芳烃组分；通过16SrDNA序列分析，初步鉴定SL-51和SL-163属于红球菌属（Rhodococcus spp．），SL-84、SL-133两株菌分别属于苍白杆菌属（Ochrobactrum sp．）、铜绿假单胞菌属（Pseudomonas sp．）。 相似文献
4.
以赤子爱胜蚓（Eisenia fetida）为供试生物,氯丹和灭蚁灵污染场地土壤为供试土壤,以蚯蚓体重及体内蛋白质含量、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性为指标,进行了不同暴露时间（1、3、7、14 d）下场地土壤中氯丹和灭蚁灵污染胁迫对蚯蚓的毒性效应研究。结果表明,随着暴露时间的延长,蚯蚓体重在氯丹和灭蚁灵作用下受到显著抑制,蚯蚓体内蛋白质、SOD和CAT活性对氯丹和灭蚁灵响应不同,其敏感性大小为CAT〉SOD〉蛋白质;在一定暴露时间内,根据暴露-剂量效应关系,表明氯丹浓度为14.13 mg.kg-1、灭蚁灵浓度为4.14 mg.kg-1可能是使蚯蚓CAT活性达到最大值的临界浓度,同时也是SOD活性受到抑制的临界浓度,超过该临界浓度可能对蚯蚓产生生态毒性效应,这为场地风险评价和修复提供了基础数据。 相似文献
5.
从石油污染土壤中富集分离、筛选出3株高效降解石油的微生物菌株,通过生理生化特性研究及16SrRNA基因序列分析,确定3株菌均属于红球菌属（Rhodococcus sp）,研究和比较了它们与实验室保存的4株菌（分别属于Gordonia sp,Comamonas sp,Pesudomonas sp）降解石油的能力。这7株菌株对石油的不同组分具有不同的降解能力,对7株菌进行不同的组合用以研究复合菌群对石油的降解。结果表明,由两株Rhodococcus sp,一株Gordonia sp和一株Pesudomonas sp组成的复合菌群D,降解石油的能力超过任何单一菌株和其他组合菌群。混合菌群D在5d的培养中能降解70.3%的石油总量和71.4%的芳香化合物。混合菌群D能降解99.8%的C13-19烷烃,92.6%的C20-26烷烃,82.2%的C27-32烷烃以及90.2%的植烷。在实验室模拟条件下,对土壤中石油的降解率达到50%以上。降解土壤中石油的最适温度为10～30℃、pH值为6.5～9.5,接种量需要在106CFU·g-1以上。 相似文献
6.
采用根箱盆栽法,研究了甲磺隆对我国南方小麦根际与非根际土壤中三大类群微生物菌群结构的影响。结果表明:在2μg/g甲磺隆浓度胁迫下,普通细菌受到显著抑制(P<0.01),耐受细菌在前30天受影响显著,但随着甲磺隆的降解和根际效应的加强而逐渐减弱;真菌是甲磺隆污染土壤中的活跃菌群,处理根际与非根际土壤中耐受真菌与对照相比30天后即达到P<0.01的显著水平;放线菌是甲磺隆胁迫下的劣势菌。微生物三大类群对甲磺隆胁迫的响应依次为放线菌>细菌>真菌,真菌的此类特性为寻求甲磺隆高效降解菌及其快速降解机制提供了可能。 相似文献
7.
氯氰菊酯污染土壤的微生物修复及对土著微生物的影响 总被引：6，自引：0，他引：6
在实验室条件下,在含有氯氰菊酯的土壤中添加氯氰菊酯和3-苯氧基苯甲酸(3-PBA)降解菌CDT3(Rhodococcussp.)和PBM11(Pesudomonassp.),同时设不加菌的对照。分别于0、3、7、15、30 d取样,测定土壤中氯氰菊酯和3-PBA的残留,同时用平板计数和变性梯度凝胶电泳(DGGE)方法分析土壤微生物群落的变化。结果显示:CDT3和PBM11在土壤中协同作用能够更好地降解氯氰菊酯及其中间产物3-PBA。氯氰菊酯对土著微生物有较强的抑制作用。投加降解菌可以消除农药对土壤微生物的抑制,有助于土著微生物种群的恢复,但短期内无法改变农药对土壤微生物结构的破坏。 相似文献
8.
通过对香港地区46个代表性土壤表层样品的8种有机氯农药（OCPs）和6种多氯联苯（PCBs）含量及其组成的分析，初步揭示了香港土壤中有机氯化合物的分布及残留情况。研究结果表明：香港土壤中有机氯农药主要是一些相对难降解的化合物如β-HCH和P，P’-DDE，两者在土壤中的平均含量分别为6．12μg kg^-1和0．41μg kg^-1，远低于荷兰的土壤修复目标值。PCBs在土壤中的检出率很低，且含量基本均小于0．1／μg kg^-1。此外。六六六（HCH）在目前的残留状态下，可能受到土壤pH（KCl）和总有机碳（TOC）的影响，而其他有机氯农药的含量并未呈现出与土壤的理化性质的相关性。 相似文献
9.
为探明养殖欧洲鳗鲡不同体位及其养殖水体中可培养菌群的组成结构,本研究利用16S rDNA序列分析法对从精养池鳗鲡的鳃部、肠道和表皮及其养殖水体中分离得到的可培养细菌进行了分子鉴定并构建了系统发育树。研究结果显示,鳃部、肠道、表皮和水体的菌密度分别为1.6×10^6 cfu/g、2.2×10^7 cfu/g、1.4×10^4cfu/cm2和4.5×10^3 cfu/mL;分离菌株分别属于γ-变形菌纲的肠杆菌属、不动杆菌属、栖水菌属,β-变形菌纲的食酸菌属,芽孢杆菌纲的葡萄球菌属、气球菌属,黄杆菌纲的金黄杆菌属和放线菌纲的微球菌属等5大类8个菌属。其中,微球菌属、肠杆菌属和栖水菌属分布最广,各样品中均有检出;而气球菌属和食酸菌属仅在鳃部分布。各生态位中,鳃部菌群最为多样,含有葡萄球菌属之外的7个属;而水体菌群种类最少,只有4个属。此外,菌群组成含量的分析结果表明,鳗鲡鳃部以金黄杆菌属（28.3%）和肠杆菌属（26.1%）居多;而肠道、表皮和养殖水体都以微球菌属占绝对优势,分别为43.6%、53.5%和74.8%。 相似文献
10.
宏基因组学探究原料乳冷藏过程菌群变化规律 总被引：2，自引：2，他引：0
为探究原料乳4 ℃冷藏期间细菌群落的变化规律，使用Illumina Hiseq测序平台，对原料乳冷藏期间微生物变化及功能注释进行宏基因组学分析。随着冷藏时间的延长，原料乳中的微生物在数量和种群构成上均发生了显著改变。冷藏72 h期间，优势菌群由不动杆菌属、链球菌属、无浆体属和梭菌属向黄杆菌属、假单胞菌属和乳球菌属逐渐演替。功能注释结果显示：复制重组修复、翻译/核糖体结构与生物发生、细胞壁/膜的生物发生、脂质代谢在冷藏前期相对丰度较高。氨基酸、碳水化合物的转运与代谢在冷藏后期相对丰度较高。其中脂质代谢与不动杆菌属显著相关（P<0.001），氨基酸代谢、碳水化合物代谢与假单胞菌属显著相关（P<0.01）。表明冷藏原料乳中不动杆菌属及假单胞菌属对乳成分影响较大。通过控制冷藏原料乳有害微生物繁殖，能够维持乳成分稳定。该研究结果可为生鲜乳保藏、液态乳灭菌控制、奶酪加工等提供理论依据。 相似文献
11.
C. Monard F. Martin-Laurent C. Vecchiato A.J. Francez P. Vandenkoornhuyse F. Binet 《Soil biology & biochemistry》2008,40(9):2253-2259
Earthworms, because they change soil physical and chemical properties, are efficient engineers that act on soil microbial community and activity. Thus they may drive pollutant biodegradation in soil such as atrazine mineralization. We hypothesized that earthworms modify the abundance of indigenous soil bacteria and the fate and activity of atrazine-degraders in the soil they engineer by bioturbation. Two bacterial strains were used as bioaugmentation agents: Pseudomonas sp. ADP and Chelatobacter heintzii, which have acquired the capacity to metabolize atrazine by carrying plasmidic atz A, B, C, D, E, F and atzA, B, C, trzD genes, respectively. We analyzed the interactions between earthworms (Lumbricus terrestris) and the indigenous and atrazine-degrading (indigenous and inoculated) bacterial communities by quantifying the 16S rRNA and the atzA gene sequence copies numbers, respectively, in different earthworm microsites. The kinetics of atrazine mineralization were measured to link the bacterial community changes with the degradation function. Digestion by earthworms significantly impacted the number of indigenous bacteria and atrazine mineralization in bioaugmented soils. Regarding the fate of the two atrazine-degraders tested, Pseudomonas sp. strain ADP survived better within the 10 days of experiment than C. heintzii in the bulk soil but the surviving fraction of C. heintzii was still metabolically active and able to mineralize atrazine. A positive “burrow-lining” effect on the atzA sequence copies number was observed in soil whether bioaugmented with C. heintzii or not (i.e. native indigenous atzA) thereby indicating that burrow-linings form a specific ‘hot spot’ for atrazine-degraders. The present study is the first to report the role of earthworms in selecting native catabolic key-genes in soil (indigenous atzA). This catabolic gene selection through earthworm soil bioturbation could be important in sustaining the degradation (detoxification) function of soil. 相似文献
12.
Laboratory experiments were carried out to investigate the fate of bacteria during and after passage through the intestinal tract of detritivore earthworms. Earthworms (Lumbricus spp.) were fed with cattle dung inoculated 7 days previously with one of five different Gram-negative bacteria. Bacterial concentrations were determined 2 days later in dung and soil, and in gut material from different parts of the earthworm intestinal tract. A high percentage (28–82%) of the total bacteria (epifluorescence direct counts) in the earthworm gut content was culturable. The concentration of total heterotrophic aerobic bacteria did not vary significantly among the five different bacterial additions and the non-inoculated control. In earthworm casts the number of total heterotrophs per gram dry matter (2.1×109) was higher than in soil (1.7×108), but lower than in the dung (1.5×1010). The test-bacteria, however, showed different survival patterns along the earthworm intestinal tract. The concentrations of Escherichia coli BJ 18 and Pseudomonas putida MM 1 and MM 11 in earthworm casts were lower than in the ingested dung, while concentrations of Enterobacter cloacae A 107 and Aeromonas hydrophila DMU 115 in dung and casts were similar. Ent. cloacae, and to aminor extent E. coli, were reduced in numbers by several orders of magnitude in the pharynx and/or crop. In the hind gut, however, the concentration of Ent. cloacae had increased to the same level as in the ingested dung, while the concentration of E. coli remained low. Our observations indicate that the bacterial flora of ingested food materials changes qualitatively and quantitatively during gut transit. 相似文献
13.
不同土地利用方式下的蚯蚓种群特征及其与土壤生物肥力的关系 总被引：3，自引：0，他引：3
采用样方法对华北平原(河北曲周)盐渍化改造区7种土地利用方式下的蚯蚓种群进行详细调查,并通过培养实验研究了蚯蚓种群特征对若干土壤生物学指标的影响。结果表明:(1)在7种土地利用调查样地中共存在蚯蚓有3个科,5个属,5个种,其中赤子爱胜蚓(Eisenia fetida)占调查样地总个体数的60%以上,梯形流蚓(Aporrectodea trapezoides)和赤子爱胜蚓两个种在本地区广泛分布,样点出现频率分别为74%和44%,为该地区的优势种;(2)不同土地利用方式的蚯蚓种群密度及生物量变化趋势是:庭院菜地>直立免耕>清茬免耕>商品菜地>传统玉米地>果园>原貌地。其中庭院菜地蚯蚓种群的平均密度和生物量分别达到272 Ind.m-2和68.04gm-2;(3)蚯蚓种群密度和物种数等种群特征与土壤基础呼吸强度、微生物生物量碳含量成显著正相关(p<0.01),与土壤基础呼吸商成显著负相关(p<0.01);(4)不同土地利用方式下,蚯蚓的种群密度、生物量等种群特征对土壤中微生物群落的影响作用显著。蚯蚓生物量越大、种群越丰富的土壤有机质、氮、磷、钾等有效成分越高,反之则相反。室内培养实验表明,随着蚯蚓个体数量增加土壤原生动物总丰度、微生物生物量碳、氮也存在升高的趋势,与用土壤生物学特性指标及土壤化学特性指标评价的结果基本一致。 相似文献
14.
Manuel Aira Niall P. McNamara Trevor G. Piearce Jorge Domínguez 《Journal of Soils and Sediments》2009,9(1):54-61
Background, aim, and scope Earthworms make a major contribution to decomposition in ecosystems where they are present, mainly acting in the drilosphere,
that is, galleries, burrows, casts, and middens. Earthworm middens are hot-spots of microbial activity and nutrient dynamics
and represent a suitable model for studying earthworm-mediated influences on soil microbial communities by alteration of the
patch structure of the microbial environment. We studied the structure and activity of the microbial communities in the soil
system formed by middens of Lumbricus terrestris and the soil below and surrounding them and the role of earthworms in maintaining these structures through time.
Material and methods We set up an experiment in which middens were either left (control) or removed from their original place (translocated) and
left in a nearby area free of earthworm activity for 2 months. After 1 and 2 months we sampled middens, soil below them, and
surrounding soil. We analyzed the phospholipid fatty acid (PLFA) profiles and measured respiratory fluxes of CO2 and CH4.
Results Microbial communities of middens clearly differed from those of soil below and surrounding soil samples, showing higher bacterial
and fungal PLFAs (p < 0.0001 and p < 0.01, respectively); furthermore, changes in microbial communities were stronger in control middens than in translocated
middens. Moreover, gram positive and negative bacterial PLFAs were greater in translocated than control middens (p < 0.0001 and p < 0.001, respectively), as well as total organic carbon (p < 0.001). Microbial activity was higher in middens than in soil below and surrounding soil samples both for CO2 (p < 0.0001) and CH4 (p < 0.0001).
Discussion Soil bioturbation by the earthworm L. terrestris was strong in their middens, but there was not any effect on soil below and surrounding soil. Microbial communities of middens
maintain their biomass and activity when earthworms were not present, whereas they decreased their biomass and increased their
activity when earthworms were present.
Conclusions Earthworms strongly enhanced microbial activity measured as CO2 production in middens, which indicates that there are hot spots for soil microbial dynamics and increasing habitat heterogeneity
for soil microorganisms. Moreover, our data strongly support the fact that the impact of this earthworm species in this soil
is restricted to their middens and increasing soil heterogeneity.
Recommendations and perspectives Our data indicate that it is not clear if earthworms enhance or depress microbial communities of middens since the microbial
activity increased, but did not modify their biomass and this was not dependent on soil organic C content. These results indicate
no competence for C pools between this anecic earthworm and microorganisms, which has been found for other earthworm species,
mainly endogeics. Conversely, they suggest some type of facilitation due to the release of additional nutrient pools in middens
when earthworms are present, through the digestion of middens' material or the addition of casts produced from other food
sources. 相似文献
15.
Microbial populations of the earthworm Eisenia foetida, their casts and farmyard manure (FYM) in which E. foetida had lived were enumerated with the dilution plate method using several media. The microbial community of earthworms appeared
to be similar to that of the FYM in which they had lived, while that of earthworms starved in distilled water for 24 h greatly
differed from that of the FYM. The community of the starved earthworms consisted exclusively (more than 90%) of fast growers,
which were defined as those that formed their colonies within 2 days, unlike that of the FYM (10–30%). About 30 isolates were
randomly chosen and some physiological properties were examined. The community of starved earthworms consisted exclusively
of Gram-negative, oxidase-positive, fermentative bacteria, whereas bacteria from the FYM were much more diverse and there
were no fermentative bacteria in the FYM. The predominant bacteria species of the starved earthworms were identified as Aeromonas hydrophila and considered to be indigenous to the earthworm E. foetida.
Received: 18 June 1999 相似文献
16.
《Applied soil ecology》2007,35(1):226-236
The gut of many soil arthropods contains a complex and mutualistic microbial community that usually assists the host with digestion. The same is probably true for earthworms, but the nature and function of the microbiota inhabiting their gut are virtually unknown. In this paper, we studied the microbial community in the gut content of the earthworm Lumbricus terrestris L. and in the bulk soil by assessing their fatty acid (FA) profiles. Our results indicated that the total FA concentration in the earthworm gut was about two orders of magnitude greater than in bulk soil, with higher concentration of bacteria (up to 500-fold), fungal and metazoan-derived FAs. Several FAs appearing in the gut were not present in bulk soil. PCA analysis revealed that the microbial community in the gut was different from that in the bulk soil, and that significant changes occurred between midgut, hindgut and proctodeum. Cluster analysis of bacterial and fungal-derived FA profiles grouped the bulk soil samples apart from the gut samples, where the hindgut profiles were more closely related to those from the proctodeum than those from the midgut. We showed important changes in the FA concentration and composition occurring at very small spatial scales inside the gut of the earthworm L. terrestris. These results have implications for understanding earthworm digestion, and they suggest that the microbial community in the earthworm gut is not a casual combination of microorganisms already present in the soil. Further study is needed to determine how these gut microbial communities are involved in earthworm digestion processes. 相似文献
17.
以蚯蚓粪肥、猪粪肥、鸡粪肥、秸秆肥、米糠、泥炭以及花生壳粉作为载体,以多菌灵降解菌Rhodococcus qingshengii djl-6和啶虫脒降解菌Pigmentiphaga sp. D-2为材料,开展了固体菌剂的研发。接种菌株djl-6及D-2后,各载体均能够促进供试菌株的生长。以蚯蚓粪肥作为载体时,菌株djl-6、D-2有效菌数释放率最高,分别为100.40%和82.03%。在保存120 d时,除花生壳粉外,其余各载体中的活菌数均高于10~7 cfu/g;以蚯蚓粪为载体的djl-6菌剂活菌数达到了7.00×10~8 cfu/g,以猪粪为载体的D-2菌剂活菌数达到了4.29×10~8 cfu/g。固体菌剂保存30 d后进行土壤农药残留降解试验,以蚯蚓粪为载体的djl-6菌剂对5 mg/kg的多菌灵降解率为94.30%,以蚯蚓粪为载体的D-2菌剂对10 mg/kg的啶虫脒降解率为81.87%。研究结果表明,以蚯蚓粪为载体的固体农残降解菌剂活菌数高、保存期长,具有较好的应用前景。 相似文献
18.
Pankaj Kumar Srivastava Poonam C. Singh Manjul Gupta Arpita Sinha Aradhana Vaish Ashish Shukla Nandita Singh Sri Krishna Tewari 《植物养料与土壤学杂志》2011,174(3):420-429
The present investigation was aimed to analyze influence of earthworm culture on nutritive status, microbial population, and enzymatic activities of composts prepared by utilizing different plant wastes. Vermicomposts were prepared from different types of leaves litter of horticulture and forest plant species by modified vermicomposting process at a farm unit. Initial thermophilic decomposition of waste load using cow‐dung slurry was done in the separate beds. The culture of Eisenia fetida was used for vermicomposting in specially designed vermibeds at the farm unit. The physico‐chemical characteristics, enzyme activities (oxido‐reductases and hydrolases), and microbial population (bacteria, fungi, free‐living nitrogen‐fixing bacteria, actinomycetes, Bacillus, Pseudomonas, phosphate‐solubilizing bacteria and fungi) of vermicomposts were found significantly higher (p < 0.05) than those of control (without earthworm inoculum). The study quantified significant contributions of earthworm culture to physico‐chemical, enzymatic, and microbiological properties of vermicompost and confirmed superior fertilization potential of vermicompost for organic farming. The agronomic utility of vermicompost was assessed on yellow mustard plant in a pot experiment. Pot soil was amended with different ratios (5%, 10%, 20%) of vermicompost and normal compost (without earthworm inoculum). Effects of these amendments on the growth of Brassica comprestis L. were studied. The significant differences (p < 0.05) in the growth of plant were observed among vermicompost‐, compost‐amended soil, and control. Vermicompost increased the root and shoot lengths, numbers of branches and leaves per plant, fresh and dry weights per plant, numbers of pods and flowers, and biochemical properties of plant leaf significantly, especially in 20% amendment. These results proved better fertilization potential of vermicompost over non‐earthworm‐inoculated compost. 相似文献
19.
20.
Lumbricus terrestris is a deep-burrowing anecic earthworm that builds permanent, vertical burrows with linings (e.g., drilosphere) that are stable and long-lived microhabitats for bacteria, fungi, micro- and mesofauna. We conducted the first non-culture based field study to assess simultaneously the drilosphere (here sampled as 0–2 mm burrow lining) composition of microbial and micro/mesofaunal communities relative to bulk soil. Our study also included a treatment of surface-applied 13C- and 15N-labeled plant residue to trace the short-term (40 d) translocation of residue C and N into the drilosphere, and potentially the assimilation of residue C into drilosphere microbial phospholipid fatty acids (PLFAs). Total C concentration was 23%, microbial PLFA biomass was 58%, and PLFAs associated with protozoa, nematodes, Collembola and other fauna were 200-to-300% greater in the drilosphere than in nearby bulk soil. Principal components analysis of community PLFAs revealed that distributions of Gram-negative bacteria and actinomycetes and other Gram-positive bacteria were highly variable among drilosphere samples, and that drilosphere communities were distinct from bulk soil communities due to the atypical distribution of PLFA biomarkers for micro- and mesofauna. The degree of microbial PLFA 13C enrichment in drilosphere soils receiving 13C-labeled residue was highly variable, and only one PLFA, 18:1ω9c, was significantly enriched. In contrast, 11 PLFAs from diverse microbial groups where enriched in response to residue amendment in bulk soil 0–5 cm deep. Among control soils, however, a significant δ13C shift between drilosphere and bulk soil at the same depth (5–15 cm) revealed the importance of L. terrestris for translocating perennial ryegrass-derived C into the soil at depth, where we estimated the contribution of the recent grass C (8 years) to be at least 26% of the drilosphere soil C. We conclude that L. terrestris facilitates the translocation of plant C into soil at depth and promotes the maintenance of distinct soil microbial and faunal communities that are unlike those found in the bulk soil. 相似文献