Threshold concentration of glucose for bacterial growth in soil |
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| Institution: | 1. Section of Microbial Ecology, Department of Biology, Lund University, Ecology Building, SE-223 62 Lund, Sweden;2. Faculty of Mathematics and Natural Science, Microbial Ecology – Centre for Ecological and Evolutionary Studies, University of Groningen, 9747 AG Groningen, The Netherlands;1. Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganeishi, Tokyo 184-8588, Japan;2. Shikoku Research Center, Forestry and Forest Products Research Institute, 2-915 Asakuranishimachi, Kochi 780-8077, Japan;3. Graduate School of Urban Environmental Science, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan;4. Graduate School of Agriculture, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan;1. Department of Biological Sciences, Northern Arizona University, PO Box 5640, Flagstaff, AZ, USA;2. Center for Ecosystem Science and Society, Northern Arizona University, PO Box 5640, Flagstaff, AZ, USA;1. Dept. of Soil Science of Temperate Ecosystems, University of Göttingen, Germany;2. Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, 142290 Pushchino, Russia;3. Department of Agroecosystem Research, BayCEER, University of Bayreuth, D-95440 Bayreuth, Germany;4. Institute for Plant Production and Agroecology in the Tropics and Subtropics, University of Hohenheim, Stuttgart, Germany;5. Dept. of Agricultural Soil Science, University of Göttingen, Germany;1. VNU-Central Institute of Natural Resources and Environmental Studies, Vietnam National University, Hanoi, Viet Nam;2. Ministry of Agriculture and Rural Development, No. 2 Ngoc Ha, Hanoi, Viet Nam;3. Vietnam National University of Forestry, Ministry of Agriculture and Rural Development, Xuan Mai, Hanoi, Viet Nam;4. Program in Climate Change and Development, Vietnam Japan University, Vietnam National University, Hanoi, Viet Nam;5. Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA;6. Program in Climate Change and Development, Vietnam Japan University, Vietnam National University, Hanoi, Viet Nam |
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| Abstract: | The activity of heterotrophic soil microorganisms is usually limited by the availability and quality of carbon (C). Adding organic substances will thus trigger a microbial response. We studied the response in bacterial growth and respiration after the addition of low amounts of glucose. First we determined if additions of glucose, at concentrations which did not result in an exponential increase in respiration after the lag phase, still stimulated bacterial growth. The second aim was to determine the threshold concentration of glucose needed to induce bacterial growth. Adding glucose-C at 1000 μg g?1 soil resulted in an increased respiration rate, which was stable during 12 h, and then decreased without showing any exponential increase in respiration. Bacterial growth, determined as leucine incorporation, did not change compared to an unamended control during the first 12 h, but then increased to levels 5 times higher than in the control. Thus, after the lag phase, a period with increasing bacterial growth, but at the same time decreasing respiration rates, was found. Similar results, but with a more modest increase in bacterial growth, were found using 500 μg glucose-C g?1 soil. Adding 50–700 μg glucose-C g?1 resulted in increased respiration during 24 h correlating with the addition rate. In contrast, bacterial growth after 24 h was only stimulated by glucose additions >200 μg C g?1 soil. Thus, there was a threshold concentration of added substrate for inducing bacterial growth. Below the threshold concentration growth and respiration appear to be uncoupled. |
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| Keywords: | Loading rates Trigger concentrations Glucose Bacterial growth Respiration Leu incorporation |
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