caa a22 4500 477112137 CHVBK 20180405111612.0 cr unu---uuuuu 170330e19960501xx s 000 0 eng 10.1007/BF00029055 doi (NATIONALLICENCE)springer-10.1007/BF00029055 Kinetics of malate transport and decomposition in acid soils and isolated bacterial populations: The effect of microorganisms on root exudation of malate under Al stress [Elektronische Daten] [David Jones, Abdul Prabowo, Leon Kochian] The kinetics and characteristics of malate degradation were studied in four acid soils ranging in both pH (4.30 to 5.00) and vegetation type. The breakdown of malate was rapid in all soils with a half life of approximately 1.7 h, Km of 1.7 mM and Vmax of 70 nmol g−1 soil h−1. No relationship was observed between malate decomposition rate and pH. Co-metabolism studies with other C and N substrates (glucose, glycine, glutamate, citrate and succinate) indicated that the microorganisms were not N limited and competitive inhibition of malate breakdown was only observed in the presence of succinate. Studies with isolated mixed bacterial cultures indicated that the bacterial malate uptake was mediated by an energy dependent, dicarboxylate transporter which can be inhibited by succinate and is independent of pH between pH 5.0 and 7.0. The Km and Vmax parameters ranged from 279-955 μM and 0.1-17 μmol mg−1 protein h−1 for the mixed bacterial cultures depending on the bacteria's previous C source. The results indicate that in acid topsoils where microbial populations are high, the microbes may provide a considerable sink for organic acids. If organic acids are being released by roots in response to an environmental stress (e.g. Al toxicity, P deficiency) it can be expected that the efficiency of these root mediated metal resistance mechanisms will be markedly reduced by rapid microbial degradation. Kluwer Academic Publishers, 1996 aluminium nationallicence bacteria nationallicence breakdown nationallicence malate nationallicence microbial biomass nationallicence rhizosphere nationallicence Jones David School of Agricultural and Forest Sciences, University of Wales, LL57 2UW, Bangor, Gwynedd, UK aut Prabowo Abdul Department of Soil Science, Brawijaya University, Malang, Indonesia aut Kochian Leon U.S. Plant Soil and Nutrition Laboratory, USDA-ARS, Cornell University, 14853, Ithaca, NY, USA aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 182/2(1996-05-01), 239-247 0032-079X 182:2<239 1996 182 11104 https://doi.org/10.1007/BF00029055 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00029055 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jones David School of Agricultural and Forest Sciences, University of Wales, LL57 2UW, Bangor, Gwynedd, UK aut NATIONALLICENCE 700 1- Prabowo Abdul Department of Soil Science, Brawijaya University, Malang, Indonesia aut NATIONALLICENCE 700 1- Kochian Leon U.S. Plant Soil and Nutrition Laboratory, USDA-ARS, Cornell University, 14853, Ithaca, NY, USA aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 182/2(1996-05-01), 239-247 0032-079X 182:2<239 1996 182 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer