caa a22 4500 397552580 CHVBK 20180308164754.0 cr unu---uuuuu 161202e199605 xx s 000 0 eng 10.1111/j.1574-6941.1996.tb00303.x doi (NATIONALLICENCE)oxford-10.1111/j.1574-6941.1996.tb00303.x Competition between Pseudomonas fluorescens Ag1 and Alcaligenes eutrophus JMP134 (pJP4) during colonization of barley roots [Elektronische Daten] [Lene Kragelund, Ole Nybroe] To use deliberately released beneficial microorganisms in the rhizosphere, we need a better understanding of the process of root colonization by seed-borne or soil-borne inocula. In this study, we determine the survival of Pseudomonas fluorescens Ag1 and Alcaligenes eutrophus JMP134, their colonization ability as affected by substrates, and the relative importance of migration versus competition for colonization of the root. Ag1 and the 2,4-dichlorophenoxy-acetic acid (2,4-D) degrader JMP134 were inoculated in sterile barley rhizosphere systems. After inoculation of seeds with individual strains, comparable population sizes were established in the rhizosphere as determined by immunofluorescence microscopic total cell counts. Both strains were motile and able to colonize the entire root system without percolating water to stimulate passive transport. Comparing immunofluorescence microscopic cell counts with colony-forming units demonstrated that a subpopulation of A. eutrophus JMP134 closely associated with the root was non-culturable in contrast to the population in rhizosphere soil. Hence, the sole use of culture-dependent methods may give misleading information about the distribution of bacteria in the rhizosphere. Colonization studies with both strains showed that co-inoculation of Ag1 and JMP134 caused a decrease of the population size of JMP134 if 2,4-D was not added to the soil as a specific carbon source for this strain. Thus, competition for limited carbon sources might influence the composition of the bacterial community in the rhizosphere. We also found that the presence of an established inoculum in the soil reduced subsequent root colonization by a seed-inoculated strain, probably by filling available niches, also indicating that competition from other bacteria may be an important factor determining the distribution of seed-borne inocula. This factor may be just as important for the distribution of bacteria as migration. © 1996 Federation of European Microbiological Societies. All rights reserved Root colonization nationallicence Competition nationallicence 2,4-Dichlorophenoxy-acetic acid nationallicence Kragelund Lene Microbiology Section, Department of Ecology and Molecular Biology, The Royal Veterinary and Agricultural University, Rolighedsvej 21, DK-1958 Frederiksberg C, Denmark aut Nybroe Ole Microbiology Section, Department of Ecology and Molecular Biology, The Royal Veterinary and Agricultural University, Rolighedsvej 21, DK-1958 Frederiksberg C, Denmark aut FEMS Microbiology Ecology Blackwell Publishing Ltd 20/1(1996-05), 41-51 20:1<41 1996 20 femsec https://doi.org/10.1111/j.1574-6941.1996.tb00303.x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1111/j.1574-6941.1996.tb00303.x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kragelund Lene Microbiology Section, Department of Ecology and Molecular Biology, The Royal Veterinary and Agricultural University, Rolighedsvej 21, DK-1958 Frederiksberg C, Denmark aut NATIONALLICENCE 700 1- Nybroe Ole Microbiology Section, Department of Ecology and Molecular Biology, The Royal Veterinary and Agricultural University, Rolighedsvej 21, DK-1958 Frederiksberg C, Denmark aut NATIONALLICENCE 773 0- FEMS Microbiology Ecology Blackwell Publishing Ltd 20/1(1996-05), 41-51 20:1<41 1996 20 femsec Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford