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Late Pleistocene organic-rich sediments (sapropels) from the eastern Mediterranean Sea harbor unknown, metabolically active chemoorganotrophic prokaryotes. As compared to the carbon-lean intermediate layers, sapropels exhibit elevated cell numbers, increased activities of hydrolytic exoenzymes, and increased anaerobic glucose degradation rates, suggesting that microbial carbon substrates originate from sapropel layers up to 217,000 years old. 16S ribosomal RNA gene analyses revealed that as-yet-uncultured green nonsulfur bacteria constitute up to 70% of the total microbial biomass. Crenarchaeota constitute a smaller fraction (on average, 16%). A slow but significant turnover of glucose could be detected. Apparently, sapropels are still altered by the metabolic activity of green nonsulfur bacteria and crenarchaeota. 相似文献
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Long-term effects of compost amendment of soil on functional and structural diversity and microbial activity 总被引：3，自引：0，他引：3
We studied the effects of applying different composts (urban organic waste, green waste, manure and sewage sludge), mineral fertilizer and compost plus mineral fertilizer on chemical, biological and soil microbiological parameters over a 12‐year period. The organic C and total N levels in soils were increased by all compost and compost + N treatments. Microbial biomass C was significantly (P ≤ 0.05) increased for some compost treatments. In addition, basal respiration and the metabolic quotient (qCO2) were significantly higher in all soils that had received sewage sludge compost. The Shannon diversity index (H), based on community level physiological profiling, showed a higher consumption of carbon sources in soils treated with compost and compost + N compared with the control. The utilization of different guilds of carbon sources varied amongst the treatments (compost, compost + N or mineral fertilizer). Cluster analysis of polymerase chain reaction‐denaturing gradient gel electrophoresis patterns showed two major clusters, the first containing the mineral fertilization and compost treatments, and the second, the composts + N treatments. No differences in bacterial community structure could be determined between the different types of compost. However, the results suggest that long‐term compost treatments do have effects on the soil biota. The results indicate that the effects on the qCO2 may be due to shifts in community composition. In this study, it was not possible to distinguish with certainty between the effects of different composts except for compost derived from sewage sludge. 相似文献
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M. Fernández-Delgado Juárez S. Waldhuber A. Knapp C. Partl M. Gómez-Brandón H. Insam 《Biology and Fertility of Soils》2013,49(5):575-585
A field study was carried out to evaluate the potential of wood ash as a fertilizer in grassland systems in combination with enriched N organic wastes. Six treatments including manure or digestate, each combined with wood ash at 0, 1, and 3 t?ha?1 were spread onto the soil to an amount equivalent to 120 kg?N ha?1. Three soil samplings and one cutting was carried out within one growing season (3 months). A higher pH value was found in manure-treated plots, the pH rise being proportional to the amount of wood ash added. Those plots amended with digestate were characterized by a larger content of total C, NH4 +, and total P (TP) regardless of the amount of ashes. Microbial activity, assessed by basal respiration and microbial biomass carbon of the differently treated soils, was not affected neither by the nature of the organic waste nor by the amount of wood ash added. However, amending soil with digestate resulted in a more efficient soil microbial community, as shown by the lower values of the metabolic quotient. Such effects were accompanied by a higher percentage of plant cover, particularly of leguminous plants in digestate-treated plots. The time of sampling (seasonal effects) was found to influence the soil pH and electrical conductivity (EC), as well as the nutrient content (total N, NH4 +, and NO3 ?). Overall, the combined use of wood ash and biogas digestate can constitute an efficient way for the disposal and recycling of both products and additionally, it may constitute an environmentally friendly alternative to mineral fertilizers for acid soils. 相似文献
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Volatile organic compounds (VOCs) in soils 总被引：1，自引：0，他引：1
Soils may act as sources or sinks of volatile organic compounds (VOCs). Many of the formed VOCs are produced by microorganisms,
and it would be a challenge to investigate soil microbial communities by studying their VOC profile. Such “volatilomics” would
have the advantage of avoiding extraction steps that are often a limit in genomic or proteomic approaches. Abundant literature
on microbially produced VOCs is available, and in particular novel detection methods allow additional insight. The aim of
this paper was to give an overview on the current knowledge of microbial VOC emissions from soils. 相似文献
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Rahel Sollmann Mariana Malzoni Furtado Beth Gardner Heribert Hofer Anah T.A. Jácomo Natália Mundim Tôrres Leandro Silveira 《Biological conservation》2011,(3):1017-1024
Owing to habitat conversion and conflict with humans, many carnivores are of conservation concern. Because of their elusive nature, camera trapping is a standard tool for studying carnivores. In many vertebrates, sex-specific differences in movements – and therefore detection by cameras – are likely. We used camera trapping data and spatially explicit sex-specific capture–recapture models to estimate jaguar density in Emas National Park in the central Brazilian Cerrado grassland, an ecological hotspot of international importance. Our spatially explicit model considered differences in movements and trap encounter rate between genders and the location of camera traps (on/off road). We compared results with estimates from a sex-specific non-spatial capture–recapture model. The spatial model estimated a density of 0.29 jaguars 100 km−2 and showed that males moved larger distances and had higher trap encounter rates than females. Encounter rates with off-road traps were one tenth of those for on-road traps. In the non-spatial model, males had a higher capture probability than females; density was estimated at 0.62 individuals 100 km−2. The non-spatial model likely overestimated density because it did not adequately account for animal movements. The spatial model probably underestimated density because it assumed a uniform distribution of jaguars within and outside the reserve. Overall, the spatial model is preferable because it explicitly considers animal movements and allows incorporating site-specific and individual covariates. With both methods, jaguar density was lower than reported from most other study sites. For rare species such as grassland jaguars, spatially explicit capture–recapture models present an important advance for informed conservation planning. 相似文献
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A study of the effects of different qualities (fresh and composted) and rates (equivalent to 120, 240, and 360 kg N ha–1) of mustard meal application on wheat yields on humid tropical vertisol was started in 1990 at Ginchi Research Station in
Ethiopia. After continuous wheat cropping for 7 years and without any further fertilisation, soil microbial parameters (basal
respiration, microbial biomass-C and N, organic-C, and ecophysiological quotients) were studied during one growth period.
After 7 years of application, mustard meal still exerted a significant positive effect on microbial biomass, basal respiration,
organic-C, Cmic : Nmic ratio, and metabolic quotient (qCO2). Organic-C, qCO2 and Cmic : Nmic ratios were higher for the compost-amended plots than plots amended with fresh mustard meal. Basal respiration, Cmic, and Cmic : Nmic ratio showed a clear seasonality, but only in manured plots. The data indicate shifts in microbial community structure (from
bacteria to fungi and from r to K strategists) and suggest positive medium-term effects of mustard meal on humid tropical
vertisol biological qualities.
Received: 25 May 1999 相似文献