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Erland Bååth - One of the best experts on this subject based on the ideXlab platform.
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The influence of nitrogen fertilisation on Bacterial Activity in the rhizosphere of barley
Soil Biology and Biochemistry, 2004Co-Authors: Katarina H Söderberg, Erland BååthAbstract:The effect of nitrogen addition on the Activity of rhizosphere bacteria was studied using barley seedlings. Three different nitrogen sources were added to the soil (nitrate, ammonium and ammonium + nitrate) at four different concentrations (0, 100, 300 and 500 mg N kg(-1) soil) and the plants were allowed to grow for 6 weeks. The Bacterial Activity was estimated by measuring thymidine and leucine incorporation into bacteria extracted using homogenisation-centrifugation. Bulk soil Bacterial Activity was low compared with that of rhizosphere bacteria. Nitrogen addition did not affect the Activity of the bulk soil bacteria, indicating that the Activity was not nitrogen limited. The thymidine and leucine incorporation rates of rhizosphere bacteria decreased when ammonium or ammonium + nitrate was applied compared with the non-amended controls. No effect on Bacterial Activity was found following nitrate addition. There was a significant positive correlation between rhizosphere Bacterial Activity and rhizosphere pH. Shoot length following ammonium treatment was significant lower than in the non-amended control, while nitrate and ammonium + nitrate addition had no effect. This indicates that the varying effects due to nitrogen sources on rhizosphere Bacterial Activity were not due to effects on plant growth.
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Ectomycorrhizal mycelia reduce Bacterial Activity in a sandy soil
FEMS Microbiology Ecology, 1996Co-Authors: Pål Axel Olsson, Roger D. Finlay, Michel Chalot, Erland Bååth, Bengt SöderströmAbstract:Bacterial Activity was studied in a growth system containing Pinus contorta seedlings inoculated with different mycorrhizal fungi. Nylon nets enabled separation of soil compartments with extramatrical mycorrhizal hyphae from soil compartments with roots and mycelium. In three separate experiments Bacterial Activity, estimated as thymidine incorporation, was reduced in soils with Paxillus involutus hyphae compared to controls without mycorrhizal hyphae. This effect was found irrespective of compartments with and without roots were compared. Laccaria bicolor only reduced the Activity in one of these three experiments. Thelephora terrestris (tested in two experiments), Laccaria proxima, Suillus variegatus and Hebeloma crustuliniforme (one experiment), also reduced the thymidine and leucine incorporation rates of bacteria. The reduction for these fungi varied between 20% and 50% in all experiments. Numbers of viable bacteria appeared to be reduced by T. terrestris, L. proxima, S. variegatus and H. crustuliniforme in one experiment, while no effect was seen in the other experiments.
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Bacterial Activity in a forest soil after soil heating and organic amendments measured by the thymidine and leucine incorporation techniques
Soil Biology and Biochemistry, 1996Co-Authors: Montserrat Díaz-raviña, Angeles Prieto, Erland BååthAbstract:Abstract The effects of soil heating (200°C, 1 h) and organic amendments (straw and poultry manure) on Bacterial Activity in a forest soil were studied in a laboratory experiment. Measurements were made over a 15-week incubation using the thymidine (TdR) and leucine (Leu) incorporation techniques. Soil heating initially reduced TdR and Leu incorporation rates by 96–98% within 2 weeks of incubation. Thereafter the Bacterial Activity recovered, but by the end of the incubation the values were still lower than in the corresponding unheated soil. Reinoculation of heated soil with fresh soil improved the reestablishment of Bacterial Activity after a long lag, since the values were comparable to those observed for the unheated soil only after 13 weeks of incubation. The organic amendments affected Bacterial Activity in both unheated and heated soils. An enhanced Bacterial Activity was found within 2 weeks after the addition of straw or poultry manure to the unheated soils, the increase being greater and maintained longer for the latter treatment. In the heated soil no effect of straw addition was detected, while a large increase in Bacterial Activity following poultry manure treatment was observed after a long lag (up to 8 weeks). The presence of a toxic substance appeared to be the cause of the prolonged reduced Bacterial Activity in the heated soils, since an inhibitory effect of water extract from heated soil was found on TdR and Leu incorporation rates of bacteria from both unheated and heated soils. Furthermore, the inhibition was less pronounced for bacteria from the heated soil, indicating that a Bacterial community tolerant to the toxic substances had developed.
Carlos M. Duarte - One of the best experts on this subject based on the ideXlab platform.
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Bacterial Activity and diffusive nutrient supply in the oligotrophic central atlantic ocean
Aquatic Microbial Ecology, 2009Co-Authors: Josep M. Gasol, Evaristo Vazquezdominguez, Dolors Vaqué, Susana Agustí, Carlos M. DuarteAbstract:Growing evidence of inorganic nutrient limitation on oceanic bacteria suggests a global dependence of Bacterial Activity and production on rates of nutrient supply. The present study exam- ined whether surface Bacterial abundance is significantly related to water column stability, and whether Bacterial Activity and growth rate are related to the rate of diffusive supply of inorganic nutrients to the mixed layer in the Central Atlantic during 2 meridional cruises. The 2 cruises were run under very different oceanic conditions, with relatively low values of Bacterial Activity in spring 1995 and relatively higher values in fall 1995. We obtained depth-resolved data in the second cruise and found that the integrated value of Bacterial production was also related to the rate of nutrient supply, while integrated particulate primary production and chlorophyll concentration were not. There was also no relationship between particulate primary production and Bacterial production. The relationship between nutrient supply and integrated Bacterial production was tested with data from a mesocosm experiment showing a good fit to the pattern obtained in the Atlantic. Average Bacterial production was ~21% of primary production in the Central Atlantic, with values ranging between 5 and 100%, and higher values in the tropical areas. The demonstration of a direct relationship between nutrient supply and Bacterial Activity helps to explain a relatively large Bacterial biomass as compared to phytoplankton biomass, a low Bacterial growth efficiency, and a high Bacterial carbon demand relative to contemporaneous primary production often measured in the open ocean, as well as the accumulation of dissolved organic carbon (DOC) observed in nutrient-limited oligotrophic seas.
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The effect of nutrient additions on Bacterial Activity in seagrass (Posidonia oceanica) sediments
Journal of Experimental Marine Biology and Ecology, 1998Co-Authors: Nancy I. López, Javier Romero, Carlos M. Duarte, Ferrán Vallespinós, Teresa AlcoverroAbstract:The influence of nutrient additions on benthic Bacterial Activity under seagrass meadows was tested by enriching five seagrass (Posidonia oceanica) meadows with nutrients over one year. We found a highly significant response of benthic Bacterial Activity to nutrient additions, which was reflected in greater (about two-fold) ammonification rates and, to a smaller extent, a significant tendency for a greater exoenzymatic Activity. Nutrient additions significantly raised Bacterial Activity, without altering the seasonal changes in Bacterial Activity. As a result of the increased Bacterial Activity, the organic content of the sediments declined significantly, by about 33%, after one year of nutrient addition. Hence, nutrient additions to the seagrass meadows enhance seagrass production but also accelerate Bacterial decomposition of seagrass carbon, thereby reducing the capacity of the sediments to store organic carbon. These results demonstrate that sediment nutrient availability limits Bacterial Activity in these Posidonia oceanica meadows, and identify bacteria as important nutrient consumers in these systems.
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Bacterial Activity in NW Mediterranean seagrass (Posidonia oceanica) sediments
Journal of Experimental Marine Biology and Ecology, 1995Co-Authors: Nancy I. López, Javier Romero, Carlos M. Duarte, Ferrán Vallespinós, Teresa AlcoverroAbstract:Abstract We examine here the hypothesis that benthic Bacterial Activity in seagrass [ Posidonia oceanica (L.) Delile] meadows is dependent on seagrass growth and availability of inorganic nutrients in the sediments. This was achieved by measuring Bacterial Activity (ammonification rates, and exoproteolytic and exoglucosidase activities) during an annual cycle in five P. oceanica meadows in the NW Mediterranean. Benthic Bacterial Activity was high, and tended to increase with increasing seagrass production. This trend is likely to involve a direct effect derived from the greater supply of organic carbon in productive meadows, and an indirect effect derived from the fact that productive meadows develop over nutrient-rich sediments and yield nutrient-rich detritus. Phosphorus availability to bacteria was low, for plant detritus was deficient in phosphorus relative to Bacterial requirements, and Bacterial Activity was reduced after seagrasses depleted inorganic phosphorus from the sediments at the onset of exponential plant growth. These results indicate that, on local and annual time scales, benthic Bacterial Activity is directly related to seagrass production in the NW Mediterranean, because of enhanced inputs of organic matter by the seagrasses, while on seasonal scales, bacteria and seagrass metabolism are inversely related, apparently because of competition for inorganic nutrients.
Liisa Tuominen - One of the best experts on this subject based on the ideXlab platform.
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Comparison of leucine uptake methods and a thymidine incorporation method for measuring Bacterial Activity in sediment
Journal of Microbiological Methods, 1995Co-Authors: Liisa TuominenAbstract:Abstract Three [ 14 C]leucine uptake methods and a [ 3 H]thymidine method for measuring Bacterial Activity in sediment were compared. For leucine uptake, a combustion method, in which prior to combustion sediment was washed with ethanol, yielded the most consistent results. The TCA extraction methods with a filtration step yielded very variable and much lower results than the combustion method. A high concentration of leucine was needed to reach the saturation level (13.7 μM), but that was not found to enhance Bacterial Activity. No clear saturation level for thymidine incorporation was achieved for two of the four lake sediments tested. Therefore, and because of other weaknesses of the method, the thymidine incorporation underestimated the Bacterial carbon production in sediment.
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Comparison of methods for inhibiting Bacterial Activity in sediment.
Applied and environmental microbiology, 1994Co-Authors: Liisa Tuominen, Timo Kairesalo, Helinä HartikainenAbstract:Dilute formaldehyde was the most suitable treatment to inhibit sediment bacteria, since Bacterial Activity remained low during long-term incubations and the chemical changes in the sediment were minimal. The inhibiting effects of HgCl2, autoclaving, and gamma radiation were diminished during longer incubations; these treatments also caused increases in dissolved nutrients.
Teresa Alcoverro - One of the best experts on this subject based on the ideXlab platform.
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The effect of nutrient additions on Bacterial Activity in seagrass (Posidonia oceanica) sediments
Journal of Experimental Marine Biology and Ecology, 1998Co-Authors: Nancy I. López, Javier Romero, Carlos M. Duarte, Ferrán Vallespinós, Teresa AlcoverroAbstract:The influence of nutrient additions on benthic Bacterial Activity under seagrass meadows was tested by enriching five seagrass (Posidonia oceanica) meadows with nutrients over one year. We found a highly significant response of benthic Bacterial Activity to nutrient additions, which was reflected in greater (about two-fold) ammonification rates and, to a smaller extent, a significant tendency for a greater exoenzymatic Activity. Nutrient additions significantly raised Bacterial Activity, without altering the seasonal changes in Bacterial Activity. As a result of the increased Bacterial Activity, the organic content of the sediments declined significantly, by about 33%, after one year of nutrient addition. Hence, nutrient additions to the seagrass meadows enhance seagrass production but also accelerate Bacterial decomposition of seagrass carbon, thereby reducing the capacity of the sediments to store organic carbon. These results demonstrate that sediment nutrient availability limits Bacterial Activity in these Posidonia oceanica meadows, and identify bacteria as important nutrient consumers in these systems.
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Bacterial Activity in NW Mediterranean seagrass (Posidonia oceanica) sediments
Journal of Experimental Marine Biology and Ecology, 1995Co-Authors: Nancy I. López, Javier Romero, Carlos M. Duarte, Ferrán Vallespinós, Teresa AlcoverroAbstract:Abstract We examine here the hypothesis that benthic Bacterial Activity in seagrass [ Posidonia oceanica (L.) Delile] meadows is dependent on seagrass growth and availability of inorganic nutrients in the sediments. This was achieved by measuring Bacterial Activity (ammonification rates, and exoproteolytic and exoglucosidase activities) during an annual cycle in five P. oceanica meadows in the NW Mediterranean. Benthic Bacterial Activity was high, and tended to increase with increasing seagrass production. This trend is likely to involve a direct effect derived from the greater supply of organic carbon in productive meadows, and an indirect effect derived from the fact that productive meadows develop over nutrient-rich sediments and yield nutrient-rich detritus. Phosphorus availability to bacteria was low, for plant detritus was deficient in phosphorus relative to Bacterial requirements, and Bacterial Activity was reduced after seagrasses depleted inorganic phosphorus from the sediments at the onset of exponential plant growth. These results indicate that, on local and annual time scales, benthic Bacterial Activity is directly related to seagrass production in the NW Mediterranean, because of enhanced inputs of organic matter by the seagrasses, while on seasonal scales, bacteria and seagrass metabolism are inversely related, apparently because of competition for inorganic nutrients.
Archana Naik - One of the best experts on this subject based on the ideXlab platform.
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Pharmacognostic Studies and Anti-Bacterial Activity of Fagonia schweinfurthii Hadidi
International Journal of Pharmaceutical & Biological Archive, 2017Co-Authors: Archana NaikAbstract:Fagonia schweinfurthii Hadidi is a small spiny herb growing in dry rocky areas of world which is known in scientific and folkloric literature due to its medicinal uses. The present paper deals with pharmacognostic studies and anti-Bacterial Activity of F. schweinfurthii Hadidi. Pharmacognostic studies and anti-Bacterial Activity was carried out from the shade-dried whole plant material of F. schweinfurthii which was found to be good source of alkaloids, tannins, carbohydrates, starch, terpenoids, saponins and mucilage whereas steroids and anthraquinones were absent. Physico-chemical evaluation for ash analysis, percent extractive and moisture content was carried out. These findings will be useful towards establishing purity and quality as well as standardization, authentication of the plant powder, which is gaining relevance in plant drug research. The powdered drug was extracted polarity wise in various solvents, tested against various Bacterial strains namely Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, Staphyloco-ccus aureus, Klebsiella pneumoniae and Salmonella typhimurium. Some of the extracted fractions of the plant exhibit significant anti-Bacterial activities which revealed that F. schweinfurthii have an excellent anti-Bacterial Activity.
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Pharmacognostic Studies and Anti-Bacterial Activity of Fagonia schweinfurthii Hadidi
International Journal of Pharmaceutical & Biological Archive, 2017Co-Authors: Archana NaikAbstract:Fagonia schweinfurthii Hadidi is a small spiny herb growing in dry rocky areas of world which is known in scientific and folkloric literature due to its medicinal uses. The present paper deals with pharmacognostic studies and anti-Bacterial Activity of F. schweinfurthii Hadidi. Pharmacognostic studies and anti-Bacterial Activity was carried out from the shade-dried whole plant material of F. schweinfurthii which was found to be good source of alkaloids, tannins, carbohydrates, starch, terpenoids, saponins and mucilage whereas steroids and anthraquinones were absent. Physico-chemical evaluation for ash analysis, percent extractive and moisture content was carried out. These findings will be useful towards establishing purity and quality as well as standardization, authentication of the plant powder, which is gaining relevance in plant drug research. The powdered drug was extracted polarity wise in various solvents, tested against various Bacterial strains namely Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, Staphyloco-ccus aureus, Klebsiella pneumoniae and Salmonella typhimurium. Some of the extracted fractions of the plant exhibit significant anti-Bacterial activities which revealed that F. schweinfurthii have an excellent anti-Bacterial Activity.