title: Systemic colonization of clover (Trifolium repens) by Clostridium botulinum strain 2301.
abstract: In recent years, cases of botulism in cattle and other farm animals and also in farmers increased dramatically. It was proposed, that these cases could be affiliated with the spreading of compost or other organic manures contaminated with Clostridium botulinum spores on farm land. Thus, soils and fodder plants and finally farm animals could be contaminated. Therefore, the colonization behavior and interaction of the botulinum neurotoxin (BoNT D) producing C. botulinum strain 2301 and the non-toxin producing Clostridium sporogenes strain 1739 were investigated on clover (Trifolium repens) in a field experiment as well as in phytochamber experiments applying axenic and additionally soil based systems under controlled conditions. Plants were harvested and divided into root and shoot parts for further DNA isolation and polymerase chain reaction (PCR) assays; subsamples were fixed for fluorescence in situ hybridization analysis in combination with confocal laser scanning microscopy. In addition, we observed significant differences in the growth behavior of clover plants when inoculated with clostridial spores, indicating a plant growth promoting effect. Inoculated plants showed an increased growth index (shoot size, wet and dry weight) and an enlarged root system induced by the systemic colonization of clover by C. botulinum strain 2301. To target C. botulinum and C. sporogenes, 16S rDNA directed primers were used and to specifically detect C. botulinum, BoNT D toxin genes targeted primers, using a multiplex PCR approach, were applied. Our results demonstrate an effective colonization of roots and shoots of clover by C. botulinum strain 2301 and C. sporogenes strain 1739. Detailed analysis of colonization behavior showed that C. botulinum can occur as individual cells, in cell clusters and in microcolonies within the rhizosphere, lateral roots and within the roots tissue of clover.
authors.affiliation: Research Unit Microbe-Plant Interactions, Department for Environmental Sciences, German Research Center for Environmental Health - Helmholtz Zentrum München Neuherberg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Zeiller
authors.affiliation: Research Unit Microbe-Plant Interactions, Department for Environmental Sciences, German Research Center for Environmental Health - Helmholtz Zentrum München Neuherberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Rothballer
authors.affiliation: Bavarian Health and Food Safety Authority Oberschleißheim, Germany.
authors.forename: Azuka N
authors.initials: AN
authors.lastname: Iwobi
authors.affiliation: Institute for Applied Biotechnology in the Tropics at the Georg-August University Goettingen Goettingen, Germany.
authors.forename: Helge
authors.initials: H
authors.lastname: Böhnel
authors.affiliation: Institute for Applied Biotechnology in the Tropics at the Georg-August University Goettingen Goettingen, Germany ; miprolab GmbH Goettingen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Gessler
authors.affiliation: Research Unit Microbe-Plant Interactions, Department for Environmental Sciences, German Research Center for Environmental Health - Helmholtz Zentrum München Neuherberg, Germany.
authors.forename: Anton
authors.initials: A
authors.lastname: Hartmann
authors.affiliation: Research Unit Microbe-Plant Interactions, Department for Environmental Sciences, German Research Center for Environmental Health - Helmholtz Zentrum München Neuherberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schmid
keywords: CLSM; Clostridium botulinum; FISH; botulinum-neurotoxin D (BoNT D); diagnostic PCR; plant-associated-pathogenic-endophytic-bacteria; plant-growth-promotion