abstract book - Clostridia

CLOSTRIDIUM BOTULINUM, A PATHOGEN FOR MAN AND ANIMAL
– A SUPERIOR GROWTH PROMOTER FOR PLANTS
Frank Gessler 1 , Azuka N. Iwobi 2 , Michael Schmid 2 , Anton Hartmann 2 ,
Helge Böhnel 3
1 miprolab GmbH, Göttingen, Germany, gessler@miprolab.com
2 Helmholtz Zentrum München, German Research Center for
Environmental Health (GmbH), Department Microbe-Plant-Interactions,
Neuherberg, Germany
3 Institute for Applied Biotechnology in the Tropics at the University of
Göttingen, Germany
Clostridium botulinum is well-known for its pathogenicity due its highly
potent neurotoxins. Generally considered being a soil-bacterium, few
aspects are known on the soil life of this species.
In a field experiment the topsoil of the experimental plots was mixed
with compost spiked with increasing amounts of C. botulinum type D
spores. A grass seed mix with clover was sown. We found that C.
botulinum persisted over 3 years, the whole observation period. In
spring of year 2 of the experiment the growth of clover was observed,
but exclusively on the plots treated with C. botulinum spores. The yield
correlated to the amount of spores introduced into soil at the beginning
of the experiment. In the higher spore concentrations the total biomass
increased by 2.6 times compared to the controls. Investigations of the
root zone revealed an increasing spore gradient from the rhizosphere to
the root surface of the clover.
In a subsequent growth chamber experiment the colonization of clover
by toxigenic and non-pathogenic C. botulinum strains was investigated.
Spores of the bacteria, in combination with Rhizobia were applied to the
clover. The harvested plants were subjected to fluorescence in situ
hybridization (FISH). Both toxin-producing and non-pathogenic
C. botulinum strains were identified as endophytic colonizers of clover.
Additionally, a plant growth promotion effect was observed in the
growth chamber experiment as well.
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