Bacillus thuringiensisandBacillus weihenstephanensisInhibit the Growth of PhytopathogenicVerticilliumSpecies.
Verticilliumwilt causes severe yield losses in a broad range of economically important crops worldwide. As many soil fumigants have a severe environmental impact, new biocontrol strategies are needed. Members of the genusBacillusare known as plant growth-promoting bacteria (PGPB) as well as biocontrol agents of pests and diseases. In this study, we isolated 267Bacillusstrains from root-associated soil of field-grown tomato plants. We evaluated the antifungal potential of 20 phenotypically diverse strains according to their antagonistic activity against the two phytopathogenic fungiVerticillium dahliaeandVerticillium longisporum. In addition, the 20 strains were sequenced and phylogenetically characterized by multi-locus sequence typing (MLST) resulting in 7 differentBacillus thuringiensisand 13Bacillus weihenstephanensisstrains. AllB. thuringiensisisolates inhibitedin vitrothe tomato pathogenV. dahliaeJR2, but had only low efficacy against the tomato-foreign pathogenV. longisporum43. AllB. weihenstephanensisisolates exhibited no fungicidal activity whereas threeB. weihenstephanensisisolates showed antagonistic effects on both phytopathogens. These strains had a rhizoid colony morphology, which has not been described forB. weihenstephanensisstrains previously. Genome analysis of all isolates revealed putative genes encoding fungicidal substances and resulted in identification of 304 secondary metabolite gene clusters including 101 non-ribosomal polypeptide synthetases and 203 ribosomal-synthesized and post-translationally modified peptides. All genomes encoded genes for the synthesis of the antifungal siderophore bacillibactin. In the genome of oneB. thuringiensisstrain, a gene cluster for zwittermicin A was detected. Isolates which either exhibited an inhibitory or an interfering effect on the growth of the phytopathogens carried one or two genes encoding putative mycolitic chitinases, which might contribute to antifungal activities. This indicates that chitinases contribute to antifungal activities. The present study identifiedB. thuringiensisisolates from tomato roots which exhibitedin vitroantifungal activity againstVerticilliumspecies.
Göttingen Genomics Laboratory, Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August-University Gottingen, Germany.
Jacqueline
J
Hollensteiner
Göttingen Genomics Laboratory, Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August-University Gottingen, Germany.
Franziska
F
Wemheuer
Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics and Göttingen Center for Molecular Biosciences, Georg-August-University Gottingen, Germany.
Rebekka
R
Harting
Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics and Göttingen Center for Molecular Biosciences, Georg-August-University Gottingen, Germany.
Anna M
AM
Kolarzyk
Göttingen Genomics Laboratory, Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August-University Gottingen, Germany.
Stefani M
SM
Diaz Valerio
Göttingen Genomics Laboratory, Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August-University Gottingen, Germany.
Anja
A
Poehlein
Göttingen Genomics Laboratory, Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August-University Gottingen, Germany.
Elzbieta B
EB
Brzuszkiewicz
Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics and Göttingen Center for Molecular Biosciences, Georg-August-University Gottingen, Germany.
Kai
K
Nesemann
Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics and Göttingen Center for Molecular Biosciences, Georg-August-University Gottingen, Germany.
Susanna A
SA
Braus-Stromeyer
Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics and Göttingen Center for Molecular Biosciences, Georg-August-University Gottingen, Germany.
Gerhard H
GH
Braus
Göttingen Genomics Laboratory, Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August-University Gottingen, Germany.
Rolf
R
Daniel
Göttingen Genomics Laboratory, Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August-University Gottingen, Germany.
Heiko
H
Liesegang
Bacillus thuringiensis; Bacillus weihenstephanensis; Verticillium; antifungal activity; bacterial-fungal interaction; biopesticide; chitinase; plant pathogen