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Developments in soil microbiology since the mid 1960s 总被引：11，自引：0，他引：11
Heribert Insam 《Geoderma》2001,100(3-4):389-402
Since the 1960s, soil microbiology underwent major changes in methods and approaches and this review focuses on the developments in some selected aspects of soil microbiology. Research in cell numbers of specific bacterial and fungal groups was replaced by a focus on biochemical processes including soil enzyme activities, and flux measurements of carbon and nutrients. Ecologists focused on soil microbial pools whereas soil microbial biomass as an important source and sink of nutrients were recognized in agriculture. Soil microbiologists started to use structural components like phospholipid fatty acids for quantification of specific microbial groups without the need to cultivate them. In the last decade, molecular approaches allowed new insights through the analysis of soil extract DNA showing an unexpected diversity of genomes in soil. At the end of the review a brief outlook is given on the future of soil microbiology which ranges from in situ identification of bacteria, to routine assays of microbial communities by microarray technology. 相似文献
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For ruminants, there is a narrow span betweennutritional deficiency of Molybdenum and its potential toxicity. Molybdenosis occurs among cattlefeeding on forage with Mo concentrations above10 μg g-1 or a Cu:Mo ratio <2. In the areaunder investigation forage Mo contents in the valleyare as high as 180 μg g-1 due to industrialpollution, while the alpine pastures, where cattlegraze during summer, are nutrient (e.g. Cu) deficient.When driven to the valley pastures in fall, animalsoften fell ill with molybdenosis, and several died.The aim of the study was to remediate this 300 ha area. Two approaches were attempted: (1) to reduce theMo contents of the forage by immobilizing soil Mo, and(2) to increase plant Mo contents by mobilizing soilMo to increase plant Mo which may then be removed fromthe system (phytoremediation).In a soil extraction experiment we demonstrated thatphosphate fertilization, ammonium sulfate amendment,vermiculite, humic acid and sewage sludge increased Moleaching by 30 to 110%. Fe-humate and Mn-humateapplication decreased Mo in the leachate from96 μg L-1 to 55 and 7 μg L-1,respectively. Plant Mo contents were increased up to170% by P-fertilizer and up to 150% by vermiculite.Conversely, sewage sludge, Fe- and Mn-humate decreasedplant Mo contents by 60, 40 and 75% in thegreenhouse. In the field study, the effects weresmaller, but Mo export through plant harvest increasedby 88% after P-fertilization and 84% aftervermiculite amendment. Mn-humate and sewage sludgedecreased plant Mo content by 25 and 40%,respectively, rendering the forage suitable forfeeding of ruminants. P-fertilization and vermiculitemay thus be recommended for the severely contaminatedsites to enhance phytoremediation through Mo export,and Mn-humate and sewage sludge application appearsuited to remediate the less severely contaminated sites. 相似文献
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Community level physiological profiles (CLPPs) have been implemented in many European soil monitoring programmes as a rapid tool for the assessment of the functional properties of soil microbial communities. However, this technique has not been harmonized among different laboratories. In this experiment, the changes of the CLPPs after storage of three Mediterranean forest soils were characterised for two sampling depths. The methods to store the samples were cooling, freezing and room temperature storage. Data presented in this study provide evidence that substantial changes can occur to the soil microbial community functions, regardless of the kind of storage. Changes in functional diversity and substrate evenness depended on the profile and sampling depth. The rate of consumption of the groups of substrates, however, shifted towards an enhanced utilisation of carboxylic acids, phenols and/or amines after 1 month storage at 4 °C, regardless of the profile or sampling depth. This was attributed to the physical disruption of soil aggregates and exposure of relatively recalcitrant occluded organic matter. These effects levelled out during 1-year storage. The great sensitivity of CLPPs to storage treatment suggests to take care for immediate analysis after sampling. In case fresh samples are not available, freezing is recommended as a convenient alternative; in that case, however, the kinetic approach is required for data analysis. 相似文献
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Munro LJ Curioni A Andreoni W Yeretzian C Watzke H 《Journal of agricultural and food chemistry》2003,51(10):3092-3096
Aroma is central to a pleasurable eating/drinking experience but is one of the most labile components of food. Coffee is an outstanding example. Attempts to avoid or control aroma degradation are often frustrated by ignorance of the microscopic mechanisms that are responsible for it. One of the processes most frequently invoked is radical formation, yet the identity of the radicals and their involvement in aroma degradation are poorly understood at the molecular level. Here a step forward in the fundamental understanding of this complex problem is taken by identifying the most relevant radicals and their products using first-principles calculations. Over 100 radicals originating from key aroma compounds found in coffee and other foods have been studied and classified according to an unambiguous criterion: their thermodynamic stability relative to common radical sources. This classification scheme predicts that most aroma molecules are resistant to both peroxidation and attack from phenolic antioxidants but are unstable with respect to radicals such as .OH. Dimers--generated from radical reactions--were also considered, and the most volatile species, which may further contribute to coffee aroma degradation, were focused on. Those--which are very few indeed--that have this potential have been identified. 相似文献
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Summary The relationship between Folsomia candida and chitin-degrading microorganisms was studied. On chitin agar, 1010 bacteria were isolated per g faeces, and 3.8×1011 bacteria per g gut contents, 1/3 of them showing a clear (chitin-free) zone around the colony. The most abundant chitin-degrading bacteria were Xanthomonas maltophilia and Curtobacterium sp. To determine the bacterial contribution in the use of chitin by F. candida, a feeding experiment was carried out. F. candida were fed with chitin, either amended with or without tetracycline as an inhibitor of bacteria. When tetracycline was omitted the biomass of F. candida was increased compared to those fed chitin with tetracycline. However, this result was observed only when the food replacement intervals were long enough to allow bacterial colonization before ingestion of the food. In a food-selection experiment, a preference for chitin colonized with microorganisms as opposed to sterile chitin was found. The results indicate that a mutualistic symbiosis of F. candida with chitinolytic microorganisms is likely to enhance chitin degradation. This relationship is not only intra-intestinal but also involves an extra-intestinal phase.Dedicated to the late Prof. Dr. W. Kühnelt 相似文献
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J. M. Lynch A. Benedetti H. Insam M. P. Nuti K. Smalla V. Torsvik P. Nannipieri 《Biology and Fertility of Soils》2004,40(6):363-385
This review mainly discusses three related topics: the application of ecological theories to soil, the measurement of microbial diversity by molecular techniques and the impact of transgenic plants and microorganisms on genetic diversity of soil. These topics were debated at the Meeting on Soil Emergency held in Erice (Trapani, Italy) in 2001 for the celebration of the 50th anniversary of the Italian Society of Soil Science. Ecological theories have been developed by studying aboveground ecosystems but have neglected the belowground systems, despite the importance of the latter to the global nutrient cycling and to the presence of life on the Earth. Microbial diversity within the soil is crucial to many functions but it has been difficult in the past to determine the major components. Traditional methods of analysis are useful but with the use of molecular methods it is now possible to detect both culturable and unculturable microbial species. Despite these advances, the link between microbial diversity and soil functions is still a major challenge. Generally studies on genetically modified bacteria have not addressed directly the issue of microbial diversity, being mainly focused on their persistence in the environment, colonization ability in the rhizosphere, and survival. Concerns have been raised that transgenic plants might affect microbial communities in addition to environmental factors related to agricultural practice, season, field site and year. Transgenic plant DNA originating from senescent or degraded plant material or pollen has been shown to persist in soil. Horizontal transfer of transgenic plant DNA to bacteria has been shown by the restoration of deleted antibiotic resistance genes under laboratory in filter transformations, in sterile soil or in planta. However, the transformation frequencies under field conditions are supposed to be very low. It is important to underline that the public debate about antibiotic resistant genes in transgenic plants should not divert the attention from the real causes of bacterial resistance to antibiotics, such as the continued abuse and overuse of antibiotics prescribed by physicians and in animal husbandry. 相似文献
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B.A. Knapp S.M. Podmirseg J. Seeber E. Meyer H. Insam 《Soil biology & biochemistry》2009,41(11):2299-2307
Interactions between earthworms and microorganisms are essential for the functioning of soil ecosystems as they affect organic matter degradation and nutrient cycling. This is also true for the alpine region, where socio-economic changes lead to the increasing abandonment of pastures, which in turn, causes a considerable shift in the diet of saprotrophic invertebrates and thus impacts food web and decomposition processes. To enhance our understanding of how this diet shift influences earthworms and associated microorganisms, we studied the gut content and cast microbiota of Lumbricus rubellus (Lumbricidae, Oligochaeta), a key macrodecomposer on alpine pastureland in the Central Alps. A feeding experiment with L. rubellus and three different food sources that represent the vegetation shift from an alpine pasture to an abandoned site was set up. Earthworms were collected in the field, transferred to a climate chamber and fed with cow manure, dwarf shrub or grass litter for six weeks. PCR-DGGE (Polymerase chain reaction-denaturing gradient gel electrophoresis) analysis of the DNA extracted from the substrates, the earthworms' gut contents and casts revealed that the gut and cast microbiota was strongly influenced by the food source ingested. Cloning of bacterial 16S rRNA gene fragments demonstrated that the intestinal content was dominated by Proteobacteria, especially from the Gamma-subclass, followed by members of the phyla Bacteroidetes, Actinobacteria and Firmicutes. In contrast, Actinobacteria were detected abundantly in all samples types when a cultivation approach was used. In conclusion, the gut microbiota of L. rubellus was shown to be substantially affected by the food source ingested, suggesting that this essential macrodecomposer is exposed to the diet shift resulting from a land-use change in the alpine area. 相似文献
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Josef Kohler Brigitte A. Knapp Sebastian Waldhuber Fuensanta Caravaca Antonio Roldán Heribert Insam 《Journal of Soils and Sediments》2010,10(8):1585-1597
Purpose
In this study, we investigated the effects of elevated atmospheric CO2, drought, and inoculation with a plant-growth-promoting rhizobacterium (PGPR) or an arbuscular mycorrhizal (AM) fungus on microbial community composition and functional diversity in the rhizosphere of Lactuca sativa L. cv. Tafalla. 相似文献10.
Martin S. A. Seewald Wolfgang Singer Brigitte A. Knapp Ingrid H. Franke-Whittle Armin Hansel Heribert Insam 《Biology and Fertility of Soils》2010,46(4):371-382
The agronomic effects of composts, mineral fertiliser and combinations thereof on chemical, biological and physiological soil
properties have been studied in an 18-year field experiment. The present study aimed at tracing treatment effects by evaluating
the volatile organic compound (VOC) emission of the differently treated soils: non-amended control, nitrogen fertilisation
and composts (produced from organic waste and sewage sludge, respectively) in combination with nitrogen fertiliser. Microbial
community structure was determined by denaturing gradient gel electrophoresis (DGGE). Aerobic and anaerobic soil VOC emission
was determined after glucose amendment using proton transfer reaction–mass spectrometry (PTR-MS). After inducing VOC production
by substrate (glucose) addition and at the same time reducing oxygen availability to impair degradation of the produced VOCs,
we were able to differentiate among the treatments. Organic waste compost did not alter the VOC emissions compared to the
untreated control, whilst sewage sludge composts and mineral fertilisation showed distinct effects. This differentiation was
supported by DGGE analysis of fungal 18S rDNA fragments and confirms earlier findings on bacterial communities. Three major
conclusions can be drawn: (1) VOC patterns are able to discriminate among soil treatments. (2) Sewage sludge compost and mineral
fertilisation have not only the strongest impact on microbial community composition but also on VOC emission patterns, but
specific tracer VOCs could not be identified. (3) Future efforts should aim at a PTR-MS-linked identification of the detected
masses. 相似文献