木霉菌和番茄叶面主要微生物间的关系

对番茄叶表分离到的几种真菌和木霉菌BTW41(T.atroviride)之间相互关系作了初步研究,研究发现木霉菌具有较强的营养竞争能力,几种叶面真菌和木霉菌混合处理叶片试验中,黑曲霉菌混合木霉菌的处理会影响木霉菌在番茄叶表的定殖,使木霉菌在番茄叶表的定殖量减少,而其它几种真菌未使木霉菌定殖量减少。     

Research on Main Microorganism Groups and Their Ecological Law im Aeration Sludge Composting Process

This paper emphatically probes into main microorganism groups and their characteristics in sewage sludge aeration composition system,and relationships between these groups and the environmental factors.Researches show that there exist interactions between microorganism groups and the environmental factors,such as organic matters,temperature and pH.Organic matters and temperature are two primary factors that effect on variations of microorganism groups. pH is a non-primary environmental factor.It is also found that microbial quantity variation curve in sludge composting process is different from that of in wastewater treatment process.     

土壤: 微生物的最后栖息地?

The question is asked whether soils can be regarded as extreme environments with respect to microorganisms. After defining some extreme environments in a general sense, special properties of extreme environments are compared to soil habitats, with special emphasis laid on time frame and localities. In relation to water availability, nutrients and other properties, such places as aggregates can show properties of extreme habitats. These features, which can act at different levels of the system from the community level down to the cellular level, are summarized as stress factors. The latter, where many switches are located leading to different strategies of survival, is described as the most important one. This raises the question of how organisms have adapted to such conditions. The soil system demands a broad spectrum of adaptations and/or adjustments for a highly variable environment. The soil microorganisms' adaptation can thus be seen as the highest kind of flexibility and is more useful than any other special adaptation.     

土壤微生物生态学在农业中的应用研究综述

土壤微生物生态学是陆地生态系统研究中最重要的组成部分,是土壤学、微生物学和生态学相互渗透、相互结合的一门新兴学科。本文从研究方法、农业施肥、农业种植制度、生态防治及应用展望等方面对土壤微生物生态学的应用研究现状作了综述,加强土壤微生物生态学在农作物生长和调控应用等领域的研究具有巨大的潜在应用前景和重要意义。     

土壤微生物多样性实验研究方法概述

对有关土壤微生物多样性,包括微生物类群多样性、群落结构多样性、功能多样性以及基因多样性等的描述与表征方法进行了探讨,同时,对当前国内外土壤微生物多样性的一些实验研究方法,包括土壤微生物分离培养方法、Biolog 微平板方法、FAME 分析方法和分子生物学方法等进行了介绍和评述。并指出在土壤微生物多样性研究中,如果可能的话,需要将各种方法结合起来使用,方可得到有关土壤生物多样性的较为全面的信息和理解。     

Evolution of humic substances from unripe compost during incubation with lignolytic or cellulolytic microorganisms and effects on the lettuce growth promotion mediated byAzotobacter chroococcum

Some recalcitrant organic wastes, which contain a large proportion of lignin or cellulose, are not changed much by composting, and thus the effectiveness of the compost as fertilizer is usua.lly low. In this study, incubation of unripe compost with ligno-cellulolytic microorganisms —Trichoderma viride orBacillus spp. — was investigated to increase the degree of humification of the organic matter present, and improve ils quality as a soil amendment. High-performance liquid chromatography (HPLC) analyses together with humification indices and electrofocusing patterns were used to monitor the evolution of the humic substances during the incubation process. Plant growth effects exerted by Azotobacter chroococcum on lettuce plants growing on the previously incubated compost were affected by the length of incubation and by changes in the composition of humic substances. Higher organic matter content and better humification seem to be important factors for predictingA. chroococcum hebaviour in the rhizosphere.     

Methods for the investigation of metabolic activities and shifts in the microbial community in a soil treated with a fungicide

Samples from a sandy agricultural soil were treated with increasing amounts of a fungicide (Sportak). The effects on the soil microflora were investigated over several weeks by monitoring basal and substrate-induced respiration and basal and substrate-induced heat output. The microbial biomass, metabolic quotient (qCO₂), relative heat output (rqheat), lag phase of substrate use, and calorimetric: respirometric ratio were used as ecophysiological parametèrs. As structural and community-specific parameters, we recorded tryptophan contents and auxin metabolism, and calculated the ratios of fungal to bacterial respiration by antibiotic inhibition of substrate-induced respiration. Sportak either inhibited or stimulated the microbiota, depending on the length of exposure to the fungicide and the amount applied. Mineralization of dead biomass was reflected in increased soil tryptophan contents after the Sportak application. A shortened lag phase demonstrated inhibition and a prolonged lag phase stimulation of substrate use. This changed with the experimental phase. The rqheat and the calorimetric: respirometric ratio proved to be suitable parameters for the detection of stress metabolism (repair processes) in soil microbiota, because thermodynamic processes and catabolic and anabolic metabolism are taken into account at the same time. Following the application of Sportak, indole 3-acetic acid biosynthesis decreased while indole-3-ethanol biosynthesis increased, probably as a result of a transitional community shift from K-strategists towards r-strategists. It was not the fungicide but the formulation (mainly xylol) that damaged the organisms. A shift in the ratio of fungi to bacteria was also observed, suggesting that the bacteria were probably more sensitive to xylol than the fungi.     

Influence of soil properties on the vertical movement of genetically-marked Pseudomonas fluorescens through large soil microcosms

Summary Vertical translocation of the introduced transposon Tn5-tagged Pseudomonas fluorescens cells was studies after irrigation of 50-cm long soil columns of loamy sand. The soil in the columns was slowly brought to saturation using groundwater, and enough water was then slowly added to permit collection of the percolated water. Introduced bacteria were transported to lower soil layers to a significantly higher degree in undisturbed soil cores than in repacked cores; water transport was hampered in both core types due to high soil bulk densities. Soil bulk density affected the degree of transport of the introduced cells; progressively more cells were translocated to deeper soil layers and into the percolation water at decreasing soil bulk densities. Repeated percolation of soil at a bulk density of 1.25 caused an increase in Tn5-tagged cell numbers in the lower soil layers and in the percolated water. Further, cells initially introduced into a dry (5.3% moisture) soil were translocated to a lesser extent than cells introduced into a wetter (13% moisture) soil. Finally, wheat roots enhanced the water-induced transport of introduced cells to the 40- and 50-cm deep soil layers and into the effluent, but not to the remaining soil layers. Large soil columns such as those used in the present study are useful in assessing the transport and survival of introduced bacterial cells in soils under a variety of simulated environmental conditions.     

碳酸钙和根际作用对酸性红壤解磷微生物丰度的影响

选用玉米品种郑单958为试验材料,设置不添加碳酸钙(CK)、每千克土添加0.3g碳酸钙(Ca-0.3)和0.5g碳酸钙(Ca-0.5)3个碳酸钙处理,以相应处理未种植物土壤为非根际对照土壤,研究了碳酸钙和根际作用对酸性红壤磷酸酶活性及解磷微生物相关功能基因phoC和phoD丰度的影响。结果表明:碳酸钙添加能有效改善玉米生长,促进地上部氮、磷、钾和钙的吸收。土壤酸性磷酸酶(ACP)活性显著高于碱性磷酸酶(ALP)活性,表明酸性土壤中ACP在矿化有机磷方面占主导地位。根际土壤ACP、ALP活性和phoD基因拷贝数均显著高于非根际,而仅Ca-0.5处理ALP活性和phoD基因拷贝数显著高于CK,说明根际效应强于碳酸钙处理。phoC基因拷贝数与土壤铵态氮、硝态氮含量存在显著相关性,ALP活性和phoD基因拷贝数与土壤pH及铵态氮、硝态氮、有效磷、交换性钙含量均存在显著相关性。可见,碳酸钙和根际作用均影响酸性土壤解磷微生物功能和丰度,但根际效应更加明显,这些作用与土壤理化因子的改变密切相关。     

Regulation of urease production in soil by microbial assimilation of nitrogen

Summary Studies of the effects of different forms of N on urease production in soils amended with organic C showed that although microbial activity, as measured by CO₂ production, was stimulated by the addition of NH₄ ⁺ or NO₃ ^- to C-amended soils (200 mol glucose-C g^–1 soil), urease production was repressed by these forms of N. The addition of L-methionine sulfoximine, an inhibitor of inorganic N assimilation by microorganisms, relieved the NH₄ ⁺ and NO₃ ^- repression of urease production in C-amended soil. The addition of sodium chlorate, an inhibitor of NO₃ ^- reduction to NH₄ ⁺ by microorganisms, relieved the NO₃ ^- repression of urease production, but did not eliminate the repression associated with NH₄ ⁺. These observations indicate that microbial production of urease in C-amended soils is not directly repressed by NH₄ ⁺ or NO₃ ^-, but by products formed by microbial assimilation of these forms of N. This conclusion is supported by our finding that the biologically active L-isomers of alanine, arginine, asparagine, aspartate, and glutamine, repressed urease production in C-amended soil, whereas the D-isomers of these amino acids had little or no influence on urease production. This work suggests that urease synthesis by soil microorganisms is controlled by the global N regulon.