罕山土壤微生物群落组成对植被类型的响应

选取分布在中国东北部地区的阔叶林-针叶林-亚高山草甸这一明显的植被垂直带谱来研究植被类型对土壤微生物群落组成的影响。选取5种植被类型-山杨(Populus davidiana)(1250—1300 m),山杨(P.davidiana)与白桦(Betula platyphylla)的混交林(1370—1550 m),白桦(B.platyphylla)(1550—1720 m),落叶松(Larix principis-rupprechtii)(1840—1890 m),亚高山草甸(1900—1951 m),采用磷脂脂肪酸(Phopholipid Fatty Acids,PLFAs)分析方法测定不同植被类型下的土壤微生物群落组成。分别采用主成分分析(Principal Components Analysis,PCA)以及冗余分析(Redundancy Analysis,RDA)来解释单种特征PLFAs的分异以及土壤理化指标与微生物PLFAs指标间的相关性。结果表明不同植被类型下土壤有机碳(SOC)对土壤微生物PLFAs总量,各类群(真菌(f)、细菌(b)、革兰氏阳性菌(G+)、革兰氏阴性菌(G-))生物量以及群落结构影响显著;土壤微生物PLFAs总量及各类群的生物量随土层加深总体上表现降低趋势,G+/G-和f/b分别随土层加深总体上表现升高趋势。不同植被类型下,阔叶混交林土壤PLFAs总量及各类群生物量总体上最高;针叶林比阔叶林下的f/b和G+/G-高;亚高山草甸下低的p H值对有机碳的可利用性有一定的抑制作用,导致f/b和G+/G-的值相对较高。总之,不同植被类型下SOC对土壤微生物群落组成的影响最为显著,而较低的p H对有机碳的可利用性有一定的抑制作用;真菌对植被类型的变化比细菌更敏感,而细菌更易受可利用性养分和p H变异的影响,这对预测不同林型下的土壤微生物群落组成有重要的启示作用。     

Response of soil microbial biomass and community structures to conventional and organic farming systems under identical crop rotations

In this study the influence of different farming systems on microbial community structure was analyzed using soil samples from the DOK long-term field experiment in Switzerland, which comprises organic (BIODYN and BIOORG) and conventional (CONFYM and CONMIN) farming systems as well as an unfertilized control (NOFERT). We examined microbial communities in winter wheat plots at two different points in the crop rotation (after potatoes and after maize). Employing extended polar lipid analysis up to 244 different phospholipid fatty acids (PLFA) and phospholipid ether lipids (PLEL) were detected. Higher concentrations of PLFA and PLEL in BIODYN and BIOORG indicated a significant influence of organic agriculture on microbial biomass. Farmyard manure (FYM) application consistently revealed the strongest, and the preceding crop the weakest, influence on domain-specific biomass, diversity indices and microbial community structures. Esterlinked PLFA from slowly growing bacteria (k-strategists) showed the strongest responses to long-term organic fertilization. Although the highest fungal biomass was found in the two organic systems of the DOK field trial, their contribution to the differentiation of community structures according to the management regime was relatively low. Prokaryotic communities responded most strongly to either conventional or organic farming management.     

鸡粪有机肥对设施菜地土壤重金属和微生物群落结构的影响

通过田间试验,研究在设施菜地上施用不同剂量的鸡粪有机肥对土壤-植物系统中重金属的累积、重金属有效性和土壤微生物群落结构的影响,进一步探讨土壤微生物群落结构与土壤重金属之间的相关关系。结果表明,与对照相比,施用有机肥可提高小白菜地上部生物量,其中施肥量为60 t/hm²时值最大,增幅为59.92%;小白菜地上部Cd、Cr、Cu、Zn和As含量均大幅增加,但Pb含量无明显变化。土壤重金属Cd、Cr、Cu、Zn和As的全量均随鸡粪有机肥施加量的增加而增大,最高增幅分别为21.30%、21.58%、17.40%、19.40%和17.43%,出现明显的累积现象;施用有机肥均增加了土壤Cd、Cr、Cu、Zn和As的有效态含量,而Pb的全量和有效态含量无显著变化;除重金属Pb外,不同重金属元素全量与有效态含量均显著正相关,其中元素Zn的全量与有效态含量相关性最强。磷脂脂肪酸（PLFA）分析结果表明,土壤中含量较高的PLFA为16：0、18：1ω7c、10Me16：0和18：1ω9c,土壤微生物总PLFA和各类群PLFA含量均呈现M0.5 > M1 > CK > M2 > M4;相关性分析结果表明,土壤Cu、As全量和Cd、Cr、Cu、As有效态含量与微生物总PLFA和各类群PLFA含量均呈现显著负相关关系,其中有效态Cr和Cu含量对微生物群落结构的影响最为显著。     

Response of the microbial community to copper oxychloride in acidic sandy loam soil

AIMS: Determining the response of different microbial parameters to copper oxychloride in acidic sandy loam soil samples using cultivation-dependent and direct microscopic techniques. METHODS AND RESULTS: Culturable microbial populations were monitored for 245 days in a series of soil microcosms spiked with different copper oxychloride concentrations. Microbial populations responded differently to additional Cu. Protistan numbers and soil metabolic potential decreased. Experiments with more soil samples revealed that metabolic potential was not significantly affected by < or =100 mg kg(-1) additional Cu. However, a negative impact on protista was noted in soil containing only 15 mg kg(-1) EDTA-extractable Cu. The negative impact on protistan numbers was less severe in soils with a higher phosphorous and zinc content. CONCLUSIONS: Bacterial populations responded differently, and protista were most sensitive to elevated Cu levels. Protistan numbers in soil from uncultivated land were higher and seemed to be more sensitive to additional Cu than the numbers of these organisms in soil originating from cultivated land. SIGNIFICANCE AND IMPACT OF THE STUDY: Protistan sensitivity to small increases in Cu levels demonstrates the vulnerability of the soil ecosystem to Cu perturbations, especially when the importance of protista as link in the flow of energy between trophic levels is considered.     

Rhizodeposition shapes rhizosphere microbial community structure in organic soil

The aims of the study were to determine group specificity in microbial utilization of root-exudate compounds and whole rhizodeposition; quantify the proportions of carbon acquired by microbial groups from soil organic matter and rhizodeposition, respectively; and assess the importance of root-derived C as a driver of soil microbial community structure. Additions of 13C-labelled root-exudate compounds to organic soil and steady-state labelling of Lolium perenne, coupled to compound-specific isotope ratio mass spectrometry, were used to quantify group-specific microbial utilization of rhizodeposition. Microbial utilization of glucose and fumaric acid was widespread through the microbial community, but glycine was utilized by a narrower range of populations, as indicated by the enrichment of phospholipid fatty acid (PLFA) analysis fractions. In L. perenne rhizospheres, high rates of rhizodeposit utilization by microbial groups showed good correspondence with increased abundance of these groups in the rhizosphere. Although rhizodeposition was not the quantitatively dominant C source for microbes in L. perenne rhizospheres, relative utilization of this C source was an important driver of microbial group abundance in organic soil.     

Response of microbial activity and community structure to decreasing soil osmotic and matric potential

Low soil water content (low matric potential) and salinity (low osmotic potential) occur frequently in soils, particularly in arid and semi-arid regions. Although the effect of low matric or low osmotic potential on soil microorganisms have been studied before, this is the first report which compares the effect of the two stresses on microbial activity and community structure. A sand and a sandy loam, differing in pore size distribution, nutrient content and microbial biomass and community structure, were used. For the osmotic stress experiment, salt (NaCl) was added to achieve osmotic potentials from ?0.99 to ?13.13 MPa (sand) and from ?0.21 to 3.41 MPa (sandy loam) after which the soils were pre-incubated at optimal water content for 10d. For the matric stress experiment, soils were also pre-incubated at optimal water content for 10d, after which the water content was adjusted to give matric potentials from ?0.03 and ?1.68 MPa (sand) and from ?0.10 to 1.46 MPa (sandy loam). After amendment with 2% (w/w) pea straw (C/N 26), soil respiration was measured over 14d. Osmotic potential decreased with decreasing soil water content, particularly in the sand. Soil respiration decreased with decreasing water potential (osmotic?+?matric). At a given water potential, respiration decreased to a greater extent in the matric stress experiment than in the osmotic stress experiment. Decreasing osmotic and matric potential reduced microbial biomass (sum of phospholipid fatty acids measured after 14 days) and changed microbial community structure: fungi were less tolerant to decreasing osmotic potential than bacteria, but more tolerant to decreasing water content. It is concluded that low matric potential may be more detrimental than a corresponding low osmotic potential at optimal soil water content. This is likely to be a consequence of the restricted diffusion of substrates and thus a reduced ability of the microbes to synthesise osmolytes to help maintain cell water content. The study also highlighted that it needs to be considered that decreasing soil water content concentrates the salts, hence microorganisms in dry soils are exposed to two stressors.     

长期施用有机无机肥对潮土微生物群落的影响

微生物群落结构是土壤生态系统变化的预警及敏感指标,可用于表征土壤质量及其生态功能变化。本文用磷脂脂肪酸法研究了有机肥和NPK肥料长期施用对华北平原潮土微生物群落结构的影响及其变化特征。结果表明：长期施用有机和无机肥不仅提高了土壤有机碳、全氮、速效磷和速效钾等含量,改善了土壤酸碱度,而且显著增加了土壤微生物生物量,其中以有机肥的效果最为明显,增幅达到15.4%。长期施用肥料有机肥也改变了土壤微生物的群落结构,提高了细菌数量,降低了放线菌含量,而对真菌数量没有明显影响,导致真菌与细菌的比值下降。主成分分析表明,长期施用有机肥的土壤,细菌以含a19:0、br14:0、16:1w5c和17:1w9而真菌以含18:1w10c的微生物为优势种群,NPK处理土壤中细菌以含18:1w7、i19:0、br18:0、16:1w7t和a15:0的微生物为优势种群,CK处理中没有明显的优势种群。     

Relating microbial community structure to functioning in forest soil organic carbon transformation and turnover

Forest soils store vast amounts of terrestrial carbon, but we are still limited in mechanistic understanding on how soil organic carbon (SOC) stabilization or turnover is controlled by biotic and abiotic factors in forest ecosystems. We used phospholipid fatty acids (PLFAs) as biomarker to study soil microbial community structure and measured activities of five extracellular enzymes involved in the degradation of cellulose (i.e., β‐1,4‐glucosidase and cellobiohydrolase), chitin (i.e., β‐1,4‐N‐acetylglucosaminidase), and lignin (i.e., phenol oxidase and peroxidase) as indicators of soil microbial functioning in carbon transformation or turnover across varying biotic and abiotic conditions in a typical temperate forest ecosystem in central China. Redundancy analysis (RDA) was performed to determine the interrelationship between individual PFLAs and biotic and abiotic site factors as well as the linkage between soil microbial structure and function. Path analysis was further conducted to examine the controls of site factors on soil microbial community structure and the regulatory pathway of changes in SOC relating to microbial community structure and function. We found that soil microbial community structure is strongly influenced by water, temperature, SOC, fine root mass, clay content, and C/N ratio in soils and that the relative abundance of Gram‐negative bacteria, saprophytic fungi, and actinomycetes explained most of the variations in the specific activities of soil enzymes involved in SOC transformation or turnover. The abundance of soil bacterial communities is strongly linked with the extracellular enzymes involved in carbon transformation, whereas the abundance of saprophytic fungi is associated with activities of extracellular enzymes driving carbon oxidation. Findings in this study demonstrate the complex interactions and linkage among plant traits, microenvironment, and soil physiochemical properties in affecting SOC via microbial regulations.     

Soil microbial community responses to additions of organic carbon substrates and heavy metals (Pb and Cr)

Microcosm experiments were conducted with soils contaminated with heavy metals (Pb and Cr) and aromatic hydrocarbons to determine the effects of each upon microbial community structure and function. Organic substrates were added as a driving force for change in the microbial community. Glucose represented an energy source used by a broad variety of bacteria, whereas fewer soil species were expected to use xylene. The metal amendments were chosen to inhibit the acute rate of organic mineralization by either 50% or 90%, and lower mineralization rates persisted over the entire 31-day incubation period. Significant biomass increases were abolished when metals were added in addition to organic carbon. The addition of organic carbon alone had the most significant impact on community composition and led to the proliferation of a few dominant phylotypes, as detected by PCR-denaturing gradient gel electrophoresis of bacterial 16S rRNA genes. However, the community-wide effects of heavy metal addition differed between the two carbon sources. For glucose, either Pb or Cr produced large changes and replacement with new phylotypes. In contrast, many phylotypes selected by xylene treatment were retained when either metal was added. Members of the Actinomycetales were very prevalent in microcosms with xylene and Cr(VI); gene copy numbers of biphenyl dioxygenase and phenol hydroxylase (but not other oxygenases) were elevated in these microcosms, as determined by real-time PCR. Much lower metal concentrations were needed to inhibit the catabolism of xylene than of glucose. Cr(VI) appeared to be reduced during the 31-day incubations, but in the case of glucose there was substantial microbial activity when much of the Cr(VI) remained. In the case of xylene, this was less clear.     

有机物料种类及腐熟水平对土壤微生物群落的影响

应用Biolog方法研究了温室盆栽番茄条件下,施用不同种类及不同腐熟水平的有机物料对土壤微生物群落的影响,施用有机物料60d后取土分析土壤微生物群落多样性及土壤微生物对Biolog微平板中胺、氨基酸、糖、羧酸、聚合物和其它类碳源的利用情况,结果表明,施用有机物料可提高土壤微生物群落多样性,施用新鲜酒糟的多样性指数略高于施用腐熟10d酒糟,牛粪不同腐熟水平对多样性影响显著,且对多样性具有正向或负向的影响;对照和施用酒糟的土壤微生物对聚合物的利用率高于施用牛粪处理,施用新鲜物料处理的土壤微生物对聚合物的利用率高于施用腐熟物料处理。     

Volatilisation of metals and metalloids by the microbial population of an alluvial soil

In order to assess the microbial contribution to the volatilisation of metal(loid)s by methylation and hydridisation in the environment, we focused on soils of different origin. Here, we describe the biogenic production of volatile metal(loid) species of an alluvial soil with rather low metal(loid) contamination. The production of volatile metal(loid) compounds was monitored in soil suspensions kept under anaerobic conditions over an incubation time of 3 months. In the headspace of the samples, we detected mainly hydrids and methylated derivatives of a broad variety of elements such as arsenic, antimony, bismuth, selenium, tellurium, mercury, tin and lead, with the volatile products of arsenic, antimony and selenium representing the highest portions. Classical cultivation-dependent procedures resulted in the isolation of a strictly anaerobic Gram-positive strain (ASI-1), which shows a high versatility in transforming metal(loid) ions to volatile derivatives. Strain ASI-1 is affiliated to the species Clostridium glycolicum due to its high 16S rDNA sequence similarity with members of that species. As shown by fluorescence in situ hybridisation, strain ASI-1 amounts to approximately 2% of the total microbial flora of the alluvial soil. Since the spectrum of volatile metal(loid) compounds produced by this strain is very similar to that obtained by the whole population regarding both the broad variety of metal(loid)s converted and the preference for volatilising arsenic, antimony and selenium, we suggest that this strain may represent a dominant member of the metal(loid) volatilisating population in this habitat.     

含铜有机肥对土壤酶活性和微生物群落代谢的影响

以猪粪和麦秆为原料,向原料中添加不同浓度硫酸铜溶液模拟原料铜污染堆制有机肥,通过小白菜盆栽试验施用堆制腐熟的有机肥,研究其对土壤酶活性及群落功能多样性的影响。结果表明,与CK处理(Cu质量分数10.35mg/kg)相比,L处理(Cu质量分数300.00mg/kg)的脱氢酶活性下降了64.75%,H处理(Cu质量分数900.00 mg/kg)的脱氢酶活性下降了90.66%。在Biolog生态测试板(ECO Microplate)温育过程中,CK处理的AWCD值(Average Well Color Development)始终大于L处理和H处理。与CK处理相比,L处理和H处理96h的AWCD值分别下降了3.55%、36.59%,CK处理显著高于H处理(P<0.01)。多样性指数对含Cu有机肥有不同的响应,L处理的shannon指数最高,H处理的simpson指数最高,CK处理的Mclntosh指数及Mclntosh均匀度最高。主成分分析结果表明,对3个处理起分异作用的碳源主要是糖类和羧酸类。     

亚热带森林土壤微生物生物量及群落功能特征的城乡梯度变化

土壤微生物在土壤养分循环以及生物地球化学循环中起着重要作用,土壤微生物对环境变化响应灵敏.为研究城乡梯度环境变化对亚热带森林土壤微生物的影响,本研究选取合肥市大蜀山国家森林公园(城市林)、紫蓬山国家森林公园(远郊林)、六安市万佛山(乡村自然林)为样地,分析比较其微生物生物量碳(MBC)、微生物生物量氮(MBN)及微生物...     

The effects of mineral fertilizer and organic manure on soil microbial community and diversity

The effects of mineral fertilizer (NPK) and organic manure on phospholipid fatty acid profiles and microbial functional diversity were investigated in a long-term (21-year) fertilizer experiment. The experiment included nine treatments: organic manure (OM), organic manure plus fertilizer NPK (OM + NPK), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), fertilizer N (N), fertilizer P (P), fertilizer K (K), and the control (CK, without fertilization). The original soil was extremely eroded, characterized by low pH and deficiencies of nutrients, particularly N and P. The application of OM and OM + NPK greatly increased crop yields, soil pH, organic C, total N, P and K, available N, P and K content. Crop yields, soil pH, organic C, total N and available N were also clearly increased by the application of mineral NPK fertilizer. The amounts of total PLFAs, bacterial, Gram-negative and actinobacterial PLFAs were highest in the OM + NPK treatment, followed by the OM treatment, whilst least in the N treatment. The amounts of Gram-positive and anaerobic PLFAs were highest in the OM treatment whilst least in the P treatment and the control, respectively. The amounts of aerobic and fungal PLFAs were highest in the NPK treatment whilst least in the N and P treatment, respectively. The average well color development (AWCD) was significantly increased by the application of OM and OM + NPK, and the functional diversity indices including Shannon index (H ^′ ), Simpson index (D) and McIntosh index (U) were also significantly increased by the application of OM and OM + NPK. Principal component analysis (PCA) of PLFA profiles and C source utilization patterns were used to describe changes in microbial biomass and metabolic fingerprints from nine fertilizer treatments. The PLFA profiles from OM, OM + NPK, NP and NPK were significantly different from that of CK, N, P, K and NK, and C source utilization patterns from OM and OM + NPK were clearly different from organic manure deficient treatments (CK, N, P, K, NP, NK 6 and NPK). Stepwise multiple regression analysis showed that total N, available P and soil pH significantly affected PLFA profiles and microbial functional diversity. Our results could provide a better understanding of the importance of organic manure plus balanced fertilization with N, P and K in promoting the soil microbial biomass, activity and diversity and thus enhancing crop growth and production.     

氮添加土壤微生物群落结构影响微生物碳利用效率

尽管近年来中国氮(N)沉降水平逐渐趋于稳定,但中国东南地区N沉降相比于其他地区仍处于较高水平。N沉降对陆地生态系统碳循环过程的影响不容忽视。微生物碳利用效率(CUE)是指微生物将吸收的碳转化为生物量碳的效率,高微生物CUE意味着高土壤有机碳存储潜力。因此,探究N沉降背景下微生物CUE的变化将有助于进一步认识陆地生态系统土壤碳存储的变化。然而,目前关于N沉降下微生物群落结构的变化如何影响微生物CUE鲜有报道。在福建省泉州市戴云山国家级自然保护区的罗浮栲林通过N添加模拟N沉降。实验共包括三个N添加处理：对照(CT,+0 kg hm^-2 a^-1)、低氮(LN,+40 kg hm^-2 a^-1)和高氮(HN,+80 kg hm^-2 a^-1)。测定不同处理土壤基本理化性质、微生物生物量、酶活性和CUE,并使用高通量测序对微生物群落结构和多样性进行测定。结果表明,N添加显著影响微生物CUE,随着N添加水平的增加,CUE逐渐增加;相反,土壤pH、可提取有机碳(EOC)和微...     

Dispersal alters soil microbial community response to drought

Microbial communities will experience novel climates in the future. Dispersal is now recognized as a driver of microbial diversity and function, but our understanding of how dispersal influences responses to novel climates is limited. We experimentally tested how the exclusion of aerially dispersed fungi and bacteria altered the compositional and functional response of soil microbial communities to drought. We manipulated dispersal and drought by collecting aerially deposited microbes after precipitation events and subjecting soil mesocosms to either filter-sterilized rain (no dispersal) or unfiltered rain (dispersal) and to either drought (25% ambient) or ambient rainfall for 6 months. We characterized community composition by sequencing 16S and ITS rRNA regions and function using community-level physiological profiles. Treatments without dispersal had lower soil microbial biomass and metabolic diversity but higher bacterial and fungal species richness. Dispersal also altered soil community response to drought; drought had a stronger effect on bacterial (but not fungal) community composition, and induced greater functional loss, when dispersal was present. Surprisingly, neither immigrants nor drought-tolerant taxa had higher abundance in dispersal treatments. We show experimentally that natural aerial dispersal rate alters soil microbial responses to disturbance. Changes in dispersal rates should be considered when predicting microbial responses to climate change.     

Functional response of the soil microbial community to biochar applications

Biochar has the potential to mitigate the impacts of climate change and soil degradation by simultaneously sequestering C in soil and improving soil quality. However, the mechanism of biochar's effect on soil microbial communities remains unclear. Therefore, we conducted a global meta‐analysis, where we collected 2,110 paired observations from 107 published papers and used structural equation modeling (SEM) to analyze the effects of biochar on microbial community structure and function. Our result indicated that arbuscular mycorrhizal fungal abundance, microbial biomass C, and functional richness increased with biochar addition regardless of loads, time since application, and experiment types. Results from mixed linear model analysis suggested that soil respiration and actinomycetes (ACT) abundance decreased with biochar application. With the increase of soil pH, the effect of biochar on fungal abundance and C metabolic ability was lessened. Higher biochar pH associated with higher pyrolysis temperatures reduced the abundance of bacteria, fungi, ACT, and soil microbes feeding on miscellaneous C from Biolog Eco‐plate experiments. SEM that examined the effect of biochar properties, load, and soil properties on microbial community indicated that fungal abundance was the dominant factor affecting the response of the bacterial abundance to biochar. The response of bacterial abundance to biochar addition was soil dependent, whereas fungi abundance was mostly related to biochar load and pyrolysis temperature. Based on soil conditions, controlling biochar load and production conditions would be a direct way to regulate the effect of biochar application on soil microbial function and increase the capacity to sequester C.     

Response of compost maturity and microbial community composition to pentachlorophenol (PCP)-contaminated soil during composting

Two composting piles were prepared by adding to a mixture of rice straw, vegetables and bran: (i) raw soil free from pentachlorophenol (PCP) contamination (pile A) and (ii) PCP-contaminated soil (pile B). It was shown by the results that compost maturity characterized by water soluble carbon (WSC), TOC/TN ratio, germination index (GI) and dehydrogenase activity (DA) was significantly affected by PCP exposure, which resulted in an inferior degree of maturity for pile B. DGGE analysis revealed an inhibited effect of PCP on compost microbial abundance. The bacteria community shifts were mainly consistent with composting factors such as temperature, pH, moisture content and substrates. By contrast, the fungal communities were more sensitive to PCP contamination due to the significant correlation between fungal community shifts and PCP removal. Therefore, the different microbial community compositions for properly evaluating the degree of maturity and PCP contamination were suggested.