微生物菌剂对秸秆降解及秸秆中微生物变化规律的影响

为明确不同微生物菌剂对秸秆降解率及秸秆降解过程中秸秆周围微生物变化规律的影响，在温室大棚内进行不同微生物菌剂降解秸秆试验。以玉米秸秆为基质，设玉米秸秆（对照组）、玉米秸秆+哈茨木霉（Trichoderma harzianum）（处理1）、玉米秸秆+哈茨木霉+地衣芽胞杆菌(Bacillus licheniformis)（处理2）三个处理。研究结果显示，单独用哈茨木霉处理可显著提高秸秆降解率，前期作用尤其明显；在秸秆降解的前30 d，秸秆降解率与秸秆中可培养真菌、细菌、放线菌呈显著正相关。不同微生物菌剂对秸秆中可培养微生物数量变化有显著影响，单独接种哈茨木霉后，秸秆中可培养真菌、细菌、放线菌数在前30 d显著高于对照组和混合菌剂处理，不同处理可培养活菌数均在90～120 d达到峰值，然后开始下降。研究结果表明，不同微生物菌剂对秸秆降解有显著影响，单独用哈茨木霉处理可显著提高秸秆降解率；不同处理对秸秆中可培养真菌、细菌、放线菌的影响有显著差异。可为秸秆降解与微生物相关性研究提供参考。     

耕作方式对潮土土壤团聚体微生物群落结构的影响

为探究不同耕作方式对潮土土壤团聚体微生物群落结构和多样性的影响,采用磷脂脂肪酸(PLFA)法测定了土壤团聚体中微生物群落。试验设置4个耕作处理,分别为旋耕+秸秆还田(RT)、深耕+秸秆还田(DP)、深松+秸秆还田(SS)和免耕+秸秆还田(NT)。结果表明:与RT相比,DP处理显著提高了原状土壤和>5 mm粒级土壤团聚体中真菌PLFAs量和真菌/细菌,为真菌的繁殖提供了有利条件,有助于土壤有机质的贮存,提高了土壤生态系统的缓冲能力;提高了5～2 mm粒级土壤团聚体中细菌PLFAs量,降低了土壤革兰氏阳性菌/革兰氏阴性菌,改善了土壤营养状况;提高了<0.25 mm粒级土壤团聚体中微生物丰富度指数。总的来说,深耕+秸秆还田(DP)对土壤团聚体细菌和真菌生物量有一定的提高作用,并且在一定程度上改善了土壤团聚体微生物群落结构,有利于增加土壤固碳能力和保持土壤微生物多样性。冗余分析结果表明,土壤团聚体总PLFAs量、细菌、革兰氏阴性菌和放线菌PLFAs量与土壤有机碳相关性较强,革兰氏阳性菌PLFAs量与总氮相关性较强。各处理较大粒级土壤团聚体微生物群落主要受碳氮比、含水量、pH值和团聚体质量分数的影响,较小粒级土壤团聚体微生物群落则主要受土壤有机碳和总氮的影响。     

Field Released Transgenic Papaya Affects Microbial Communities and Enzyme Activities in Soil

Soil properties, microbial communities, and enzyme activities were studied in soil planted with transgenic or nontransgenic papaya under field conditions. The transgenic papaya contained a replicase (RP) mutant gene of the papaya ringspot virus (PRSV), which conferred resistance to the virus, the neomycin phosphotransferase II (NPT II) marker gene, which conferred Km resistance, and a cauliflower mosaic virus 35S promoter (CaMV 35S). There were significant differences (P < 0.05) in the total number of colony forming units (CFUs) of bacteria, actinomycetes, and fungi between soils planted with RP-transgenic and nontransgenic plants; total CFUs of bacteria, actinomycetes, and fungi in soil planted with transgenic papaya were significantly higher by 0.43, 0.80, and 0.46 times, respectively. Significantly higher (P < 0.05) CFUs of bacteria, actinomycetes, and fungi resistant to kanamycin (Km) were present in soils planted with the transgenic papaya than in those planted with nontransgenic papaya. Resistance quotients (CFU in the presence of a chemical relative to that without) of Km-resistant bacteria, actinomycetes and fungi were higher in soil planted with transgenic papaya, and the resistance quotients of Km-resistant bacteria, actinomycetes, and fungi in soils planted with transgenic papaya increased statistically significantly (P<0.05) from 1.5 to 2.5, from 1.2 to 2.6, and from 0.9 to 2.8 times, respectively. Soils planted with transgenic papaya had significantly higher enzyme activities of arylsulfatases (+5.4 times), alkaline phosphatases (+0.5 time), invertase (+0.5 time) and phosphodiesterases (+0.2 time), but lower enzyme activities of proteases (−2.1 times), polyphenol oxidases (−1.4 times), urease (−0.2 time) than the soils planted with nontransgenic papaya. Our results suggest that transgenic papaya could alter chemical properties, enzyme activities, and microbial communities in soil.     

巨桉连栽对土壤微生物生物量和数量的影响

为探讨巨桉连栽对土壤微生物生物量和数量的影响,采用时空互换法,研究了马尾松(Pinus massoniana)林和不同连栽代次的巨桉(Eucalyptus grandis)人工林的微生物生物量、数量与土壤理化性质的关系。结果表明,巨桉一代林的土壤微生物生物量碳、生物量氮和土壤真菌、细菌数量与马尾松林的差异不显著,放线菌数量则显著增加。随巨桉连栽代次增加,土壤微生物生物量碳、生物量氮和土壤细菌、放线菌、真菌数量均递减。回归分析表明,土壤全磷能独立解释微生物生物量氮、细菌和真菌数量71.7%、86.1%和63.0%的变异,与总孔隙度共同解释微生物生物量碳87.9%的变异,与全氮共同解释放线菌数量89.6%的变异。可见,土壤全磷较大程度解释了微生物的变化。     

喀斯特地区三种人工林土壤微生物群落结构特征

为揭示不同人工植被修复模式对喀斯特土壤微生物群落的影响,采用氯仿熏蒸提取法和磷脂脂肪酸(phospholipid fatty acid, PLFA)法研究人工构建的降香黄檀(Dalbergia odorifera)纯林(PDOP)、顶果木(Acrocarpus fraxinifolius)纯林(PAFP)、顶果木×降香黄檀混交林(MADP)对土壤微生物生物量及土壤微生物群落结构的影响。结果表明:(1)PDOP的土壤微生物生物量碳(MBC)和微生物生物量氮(MBN)含量显著高于PAFP和MADP,PAFP显著高于MADP。(2)三种人工林土壤真菌、丛枝菌根真菌和总PLFA含量无显著差异,但PDOP土壤细菌、放线菌、丛枝菌根真菌和总PLFA含量均高于PAFP和MADP,PAFP高于MADP。PDOP的土壤细菌、革兰氏阳性菌、革兰氏阴性菌、放线菌的PLFA含量显著高于MADP。MADP的真菌细菌比显著高于PDOP,但与PAFP无显著差异。(3)冗余分析表明,土壤阳离子交换量、pH和C:N是影响土壤微生物群落组成的最主要影响因子。从三种人工林的土壤微生物生物量及微生物群落结构来看,在喀斯特地区MADP并未显示出酸性土地区混交林提高土壤微生物生物量、改善土壤微生物群落结构的优势,但混交林的真菌细菌比最高,更有利于提高土壤生态系统的稳定性。     

Microflora of a coniferous forest of the Mexican basin

Summary Soil profiles were made at three locations corresponding to the three principal coniferous groups:Pinus montezumae, Abies religiosa andPinus hartwegii. The soil samples were submitted to microbiological, physical and chemical analysis. Mycorrhizic fungi were collected throughout this zone and 25 species of ectotrophic and 1 facultative mycorrhizic fungiLaccaria laccata were found.Lycoperdon perlatum andHygrophorus chrysodon were in the three communities, as wellAmanita muscaria, Boletus granulatus andCantharellus cibarius were only in the Pinus communities. The experimental condition used in order to prove symbiosis showed us several symbionts in the root for each one of the three different conifers. As regards general microflora, the greatest number of bacteria and fungi was present in the surface horizon of Abies soil; these soils are deep and moist throughout the year and with a good drainage, so that seasonal variations have little or no effect on soil environmental conditions and that favors the microbiological development. In the soils of the Pinus communities the number of actinomycetes and of bacteria is higher immediately below the surface horizon.     

The mycoflora of domesticated and wild bees (Apoidea)

Fungi including yeasts are common in the honey stomachs and provisions of diverse bees. They may be parasites, commensals or mutualistic. Yeasts, singly or in association with bacteria, are pioneer colonizers during a microbial succession in larval cells of many subterranean bees. They are followed by fungi such asAspergillus, Penicillium, Emericellopsis, Sartorya, Pseudoarachniotus, Gymnoascus, Carpenteles andFusarium. Aspergillus flavus andSaccharomyces spp. are pathogenic to many species of bees, and fungi are the main cause of declining alkali bee populations. There are 124 species of fungi, including 36 new records, associated with Apoidea; 49 species are associated with alkali bees.Cooperative investigations of the Plant Sciences Research (L. R. Batra) and Entomology (G. E. Bohart) Divisions, Agricultural Research Service, U.S. Department of Agriculture, and the Utah Agricultural Experiment Station, Logan, Utah.     

Control of survival of Ophiobolus graminis between consecutive crops of winter wheat

Under a glasshouse crop of red clover, Ophiobolus graminis (Sacc.) Sacc. in artificially colonized straws survived for longer on the soil surface than when buried, and for much longer when suspended above the soil; survival in buried straws was somewhat more prolonged in fallow soil than under clover. In field experiments with consecutive crops of winter wheat, under-sowing with red clover was not effective in reducing the incidence of take-all, possibly because of above-ground survival of the pathogen in unploughed straw. Early rotavation, however, significantly reduced disease incidence, probably because of enhanced microbial activity and competition for nitrogen in the well-aerated compost of soil and stubble.     

华西雨屏区天然常绿阔叶林土壤可培养微生物数量对模拟氮沉降的响应

为了解氮沉降对华西雨屏区天然常绿阔叶林土壤微生物数量的影响,从2013年11月至2014年12月,通过野外模拟N(NH_4NO_3)沉降,氮沉降水平分别为对照(CK 0 kg N hm~(-2)a~(-1))、低氮沉降(L 50 kg N hm~(-2)a~(-1))、中氮沉降(M 150 kg N hm~(-2)a~(-1))和高氮沉降(H 300 kg N hm~(-2)a~(-1)),研究了氮沉降对天然常绿阔叶林0—10cm和10—20cm土层土壤可培养微生物数量的影响。结果表明:华西雨屏区天然常绿阔叶林0—10cm土层的细菌、真菌和放线菌数量均显著大于10—20cm土层,氮沉降未改变原有垂直分布格局。L处理对0—10cm和10—20 cm土层土壤微生物总量无显著影响,M和H处理则显著降低了土壤微生物总量。氮沉降降低了0—10cm和10—20cm土层的细菌数量,且抑制作用随氮沉降量的增加而增强。氮沉降降低了0—10cm土层的真菌数量,但下降幅度与氮沉降量之间无明显规律;在10—20cm土层,M和H处理在夏季显著增加了真菌数量,表明适量氮沉降能有效缓解夏季土壤真菌的氮限制状态。氮沉降对0—10cm土层放线菌数量的影响表现为先促进再抑制,L和M处理增加了放线菌数量,H处理降低了放线菌数量;氮沉降增加了10—20cm土层的放线菌数量,其中M处理的促进作用最大。氮沉降对土壤微生物数量的影响随土壤深度的增加而减弱。     

降香黄檀土壤微生物数量的时空动态特征

【目的】研究降香黄檀土壤微生物数量在时间和空间上的动态特征,可为降香黄檀栽培技术的完善提供数据支持。【方法】采用稀释平板涂布法,比较分析降香黄檀根际和非根际土壤微生物三大类群(细菌、放线菌、真菌)数量的季节及垂直分布情况。【结果】(1)降香黄檀根际和非根际土壤均表现为春季细菌、真菌数量较多,冬季细菌数量较少,秋季真菌数量较少;非根际土壤放线菌冬季数量较多,秋季数量较少。(2)细菌的根际效应最为明显,其R/S为0.12~62.96;真菌次之,其R/S为0.22~2.46;放线菌的根际效应较小,其R/S为0.32~1.01。(3)降香黄檀上层土(0~20 cm)的微生物数量普遍高于其他土层;随着土层加深,微生物数量表现为逐渐下降或先下降后升高2种变化趋势。【结论】降香黄檀土壤微生物数量的分布受季节和土层的影响。     

The trade-off between growth rate and yield in microbial communities and the consequences for under-snow soil respiration in a high elevation coniferous forest

Soil microbial respiration is a critical component of the global carbon cycle, but it is uncertain how properties of microbes affect this process. Previous studies have noted a thermodynamic trade-off between the rate and efficiency of growth in heterotrophic organisms. Growth rate and yield determine the biomass-specific respiration rate of growing microbial populations, but these traits have not previously been used to scale from microbial communities to ecosystems. Here we report seasonal variation in microbial growth kinetics and temperature responses (Q₁₀) in a coniferous forest soil, relate these properties to cultured and uncultured soil microbes, and model the effects of shifting growth kinetics on soil heterotrophic respiration (R_h). Soil microbial communities from under-snow had higher growth rates and lower growth yields than the summer and fall communities from exposed soils, causing higher biomass-specific respiration rates. Growth rate and yield were strongly negatively correlated. Based on experiments using specific growth inhibitors, bacteria had higher growth rates and lower yields than fungi, overall, suggesting a more important role for bacteria in determining R_h. The dominant bacteria from laboratory-incubated soil differed seasonally: faster-growing, cold-adapted Janthinobacterium species dominated in winter and slower-growing, mesophilic Burkholderia and Variovorax species dominated in summer. Modeled R_h was sensitive to microbial kinetics and Q₁₀: a sixfold lower annual R_h resulted from using kinetic parameters from summer versus winter communities. Under the most realistic scenario using seasonally changing communities, the model estimated R_h at 22.67 mol m⁻² year⁻¹, or 47.0% of annual total ecosystem respiration (R_e) for this forest.     

小蓬竹根际土壤微生物及内生真菌多样性分析

为了解喀斯特典型物种-小蓬竹根际土壤微生物及不同部位内生真菌多样性,采用沿等高线等距离取样法采集小蓬竹根际土壤及健康植株,通过可培养对根际土微生物及内生菌进行分离,利用分子技术对其进行鉴定,根据鉴定结果构建系统发育树,并计算小蓬竹根际土壤微生物和根茎叶内生真菌多样性。结果如下：（1）共从根际土壤、根、茎、叶分离得到139个真菌菌株,隶属于27属,其中根际土壤分离得到34个真菌菌株隶属于12属,根部分离得到的63个内生真菌菌株隶属于17个属,茎部分离得到的14个内生真菌菌株隶属于8个属,叶部分离得到28个内生真菌菌株隶属于9个属;（2）根际土壤共分离得到41株细菌菌株,隶属于7个属26个种,20株放线菌菌株,隶属于1属15种;从Shannon-Wiener多样性指数、均匀度指数、Simpson指数排序来看,真菌主要表现为根 > 根际土壤 > 茎 > 叶,细菌和放线菌多样性均较低。（3）按层次聚类分析可分别将真菌、细菌、放线菌聚为3支。小蓬竹根际土壤、根、茎和叶具有丰富的微生物多样性,不同部位菌群组成存在差异性（P<0.05）,且存在以假单胞菌属、芽孢杆菌属等为优势属的抗盐耐旱菌群,这有助于揭示小蓬竹对喀斯特生境的适应性,以及为微生物-植物群落之间相互关系提供一定基础数据,为后期寻找小蓬竹相关耐性功能菌奠定基础。     

Land Use History Shifts In Situ Fungal and Bacterial Successions following Wheat Straw Input into the Soil

Soil microbial communities undergo rapid shifts following modifications in environmental conditions. Although microbial diversity changes may alter soil functioning, the in situ temporal dynamics of microbial diversity is poorly documented. Here, we investigated the response of fungal and bacterial diversity to wheat straw input in a 12-months field experiment and explored whether this response depended on the soil management history (grassland vs. cropland). Seasonal climatic fluctuations had no effect on the diversity of soil communities. Contrastingly fungi and bacteria responded strongly to wheat regardless of the soil history. After straw incorporation, diversity decreased due to the temporary dominance of a subset of copiotrophic populations. While fungi responded as quickly as bacteria, the resilience of fungal diversity lasted much longer, indicating that the relative involvement of each community might change as decomposition progressed. Soil history did not affect the response patterns, but determined the identity of some of the populations stimulated. Most strikingly, the bacteria Burkholderia, Lysobacter and fungi Rhizopus, Fusarium were selectively stimulated. Given the ecological importance of these microbial groups as decomposers and/or plant pathogens, such regulation of the composition of microbial successions by soil history may have important consequences in terms of soil carbon turnover and crop health.     

Bacterial Communities Involved in Soil Formation and Plant Establishment Triggered by Pyrite Bioweathering on Arctic Moraines

In arctic glacier moraines, bioweathering primed by microbial iron oxidizers creates fertility gradients that accelerate soil development and plant establishment. With the aim of investigating the change of bacterial diversity in a pyrite-weathered gradient, we analyzed the composition of the bacterial communities involved in the process by sequencing 16S rRNA gene libraries from different biological soil crusts (BSC). Bacterial communities in three BSC of different morphology, located within 1 m distance downstream a pyritic conglomerate rock, were significantly diverse. The glacier moraine surrounding the weathered site showed wide phylogenetic diversity and high evenness with 15 represented bacterial classes, dominated by Alphaproteobacteria and pioneer Cyanobacteria colonizers. The bioweathered area showed the lowest diversity indexes and only nine bacterial families, largely dominated by Acidobacteriaceae and Acetobacteraceae typical of acidic environments, in accordance with the low pH of the BSC. In the weathered BSC, iron-oxidizing bacteria were cultivated, with counts decreasing along with the increase of distance from the rock, and nutrient release from the rock was revealed by environmental scanning electron microscopy-energy dispersive X-ray analyses. The vegetated area showed the presence of Actinomycetales, Verrucomicrobiales, Gemmatimonadales, Burkholderiales, and Rhizobiales, denoting a bacterial community typical of developed soils and indicating that the lithoid substrate of the bare moraine was here subjected to an accelerated colonization, driven by iron-oxidizing activity.     

Saprophytic Behaviour of Some Cereal Root-Rot Fungi

The ability of four cereal root-rot fungi, Helminthosporium sativum, Curvularia ramosa, Ophiobolus graminis and Fusarium culmorum , to colonize wheat straw as saprophytes has been investigated. Test pieces of straw were buried in a graded dilution series of maizemeal-sand culture of the test fungus with unsterilized soil. For assessing percentage straws colonized, three methods were compared: (1) isolation on agar plates, (2) Garrett's (1938 b ) wheat-seedling test and (3) incubation on moist sand, to promote sporulation (the 'sand-plate' test). Curvularia ramosa and Fusarium culmorum were found to behave as vigorous competitive saprophytes of the soil-inhabiting type, whereas Helminthosporium sativum and Ophiobolus graminis proved to be weak saprophytic colonizers of the specialized root-inhabiting type.     

长期施肥对新疆灰漠土土壤微生物群落结构与功能多样性的影响

以20a新疆国家灰漠土土壤肥力与肥料效益长期定位试验为平台,采用常规培养法,结合Biolog技术对可培养微生物、生理菌群数量和碳源利用进行测定分析,研究撂荒(CK0)、耕作不施肥(CK)、不同化肥(N、NK、NP、PK、NPK)、化肥配施低量高量有机肥(NPKM1和NPKM2)和秸秆还田(NPKS)等10种处理土壤微生物特征,揭示长期施肥对土壤微生物群落结构与功能多样性的影响。结果表明:(1)可培养微生物:与CK处理相比,CK0处理显著提高了细菌、放线菌和真菌的数量(P0.05),NPKS处理微生物数量则显著降低(P0.05);不同化肥处理的细菌(除PK处理外)、放线菌(除PK和N处理外)数量也有所增加,增幅在8.14%—135.70%和15.30%—44.78%之间;真菌数量(除NK处理外)则有一定幅度的降低;NPKM1和NPKM2处理,微生物数量最高,细菌分别增加了162.20%和173.75%,放线菌增加了34.39%和39.37%,真菌增加了63.33%和488.33%;(2)生理菌群:与CK0相比,CK处理显著提高了自生固氮菌和亚硝化细菌数量(P0.05),显著降低了氨化细菌和纤维素分解菌数量(P0.05);与CK相比,NPKM1和NPKM2处理显著提高土壤中与氮素转化有关的生理菌群数量(P0.05),不同化肥处理和NPKS处理的影响不相同,NPK处理显著高于其余处理(P0.05);(3)微生物碳源利用:微生物活性表现为NK、NPKM1、NPKM2N、NPK、CKPK、NPKSCK0、NP;CK0处理3个多样性指数以及NPKM1、NPKM2和NK处理Shannon(H)指数最高,其余施肥处理差异不显著;糖类、氨基酸类、羧酸类和胺类是微生物利用的主要碳源。(4)聚类分析表明,除NP处理外,施氮处理土壤有较为相似的碳源利用,细菌和真菌与养分之间有较好的相关性,可培养微生物和生理菌群与微生物碳源利用的相关性较差。因此,长期不同施肥对新疆灰漠土土壤微生物群落结构和功能多样性产生了显著的影响,长期耕作不施肥降低了土壤微生物群落结构和功能多样性,不同化肥配合施用对微生物群落的影响不同,NPK及NPK配施有机肥可提高土壤微生物多样性。     

蚯蚓和秸秆对铜污染土壤微生物类群和活性的影响

试验设置4个Cu浓度水平：0、100、200和400 mg·kg^-1 Cu²⁺,每个Cu浓度水平设置4个处理：对照(CK)、表施秸秆(M)、接种蚯蚓(E)、同时加入蚯蚓和秸秆(ME),研究了在Cu污染土壤中加入蚯蚓和秸秆对土壤微生物数量及活性的影响.结果表明：Cu污染、秸秆和蚯蚓均明显影响土壤微生物类群; Cu污染对细菌、放线菌具有抑制作用,而对真菌没有影响;秸秆显著提高了真菌数量;蚯蚓使土壤细菌、放线菌数量显著增加,而对真菌数量影响不大.Cu污染浓度＞200 mg·kg^-1处理对微生物量碳具有抑制作用;加入秸秆或蚯蚓,可显著提高土壤微生物量碳,而且同时加蚯蚓和秸秆处理土壤微生物量碳增加最显著.加入蚯蚓和秸秆后,土壤呼吸值显著增高.Cu<200 mg·kg^-1时,蚯蚓处理土壤呼吸值最大,平均比对照高3.06～5.58倍;Cu≥200mg·kg^-1时,蚯蚓、秸秆同时加入处理土壤呼吸值最高.4个处理土壤代谢商大小顺序为：ME>E>M>CK.蚯蚓和秸秆处理对土壤NH₄⁺-N没有影响,而对土壤NO₃^--N影响各异.接种蚯蚓,可显著提高土壤NO₃^--N含量;加入秸秆,可显著降低土壤NO₃^--N含量;同时加入蚯蚓和秸秆处理NO₃^--N含量最低.相关分析表明,土壤有效态Cu(DTPA-Cu)与土壤放线菌、细菌呈显著负相关,而与土壤呼吸、土壤NO₃^--N、NH₄⁺-N含量呈显著正相关.引入秸秆和蚯蚓,可在一定程度上减缓Cu污染对微生物数量和活性的影响.     

Microbial production of biogas form organic wastes

Biogas production through bacterial digestion of water hyacinth, rice straw and sawdust inoculated with cow dung was investigated in a batch loading of laboratory digestors. It was found that the overall gas yield was 368.00 l from water hyacinth having 77.13% methane, 310.00 l from rice straw with 77.80% methane, and 144.80 l from sandust containing 62.28% methane. Along with the production of gas, the change in pH and microbial population were also monitored. The pH of the digestion mixture was initially low and found to be increasing as the digestion progressed. The total microbial population of bacteria, fungi, actinomycetes, cellulolytic organisms, and coliform bacteria were found to decrease with time.     

Study on the communities of endophytic fungi and endophytic actinomycetes from rice and their antipathogenic activities in vitro

The populations of endophytic fungi and actinomycetes from four rice cultivars in the Panyu district (Site 1) and Wushan district (Site 2) in Guangdong province, South China, were studied. The preponderant endophytic fungi and actinomycetes isolated belonged to Fusarium and Streptomyces respectively. The incidence of Streptomycetes griseofuscus ranged from 36.1 to 69% out of all the different rice cultivars from the two sites. It is the commonest population of endophytic actinomycetes, and constituted the greatest part of all the antagonistic communities. The distributions of endophytic fungi and actinomycetes in roots and leaves were different, endophytic fungi from leaves were diverse, some were organ-specific. More diverse endophytic actinomycetes were isolated from roots than from leaves. The endophytic fungi isolated from rice in Site 2 were more diverse than that in Site 1. The diversity of the endophytic actinomycetes, however, was less than that in Site 1. Acid soil in Site 2 is ideal for the growth and colonization of fungi while the alkaline soil in Site 1 is better for the growth and colonization of actinomycetes. The results suggested that differences in the chemical composition of soil could influence the endophytic microbial communities of rice plants. The endophytic fungi and actinomycetes isolated from poor-growing seedlings and susceptible rice cultivars were more abundant than that the disease-resistant counterparts. In the dual culture and activity detection of the metabolites, 41.2% of all the isolated endophytic fungi showed antagonism to rice pathogens. Fifty percent of all the isolated endophytic actinomycetes were antagonistic to those pathogens. The percentage of Streptomyces griseofuscus and hygroscopicus reached 55.4 and 21.4% of all the active actinomycetes. This revised version was published online in August 2006 with corrections to the Cover Date.     

连续施肥对农田黑土微生物功能多样性的影响

应用Biolog Eco微平板培养法研究了中国科学院海伦农业生态试验站20余年连续不同施肥处理(对照、氮磷钾、氮磷钾+秸秆、氮磷钾+猪粪1、氮磷钾+猪粪2和氮磷钾+猪粪3)下土壤微生物代谢功能多样性的变化。结果表明:长期施肥条件下,单施化肥和有机肥与化肥配施对土壤细菌、真菌数量影响不明显,但高量有机肥与化肥配施可以显著增加放线菌数量。Biolog结果表明,施用有机肥的平均颜色变化率高于单施化肥和对照。Shannon指数、Simpson指数和McIntosh指数均是有机肥和化肥配施高于化肥单施与对照。主成分分析结果表明,对照、NPK与其他几种处理有较明显的距离,说明有机肥的连年施用导致了土壤微生物代谢功能多样性的变化。