Mycosubtilin overproduction by Bacillus subtilis BBG100 enhances the organism's antagonistic and biocontrol activities.
A Bacillus subtilis derivative was obtained from strain ATCC 6633 by replacement of the native promoter of the mycosubtilin operon by a constitutive promoter originating from the replication gene repU of the Staphylococcus aureus plasmid pUB110. The recombinant strain, designated BBG100, produced up to 15-fold more mycosubtilin than the wild type produced. The overproducing phenotype was related to enhancement of the antagonistic activities against several yeasts and pathogenic fungi. Hemolytic activities were also clearly increased in the modified strain. Mass spectrometry analyses of enriched mycosubtilin extracts showed similar patterns of lipopeptides for BBG100 and the wild type. Interestingly, these analyses also revealed a new form of mycosubtilin which was more easily detected in the BBG100 sample. When tested for its biocontrol potential, wild-type strain ATCC 6633 was almost ineffective for reducing a Pythium infection of tomato seedlings. However, treatment of seeds with the BBG100 overproducing strain resulted in a marked increase in the germination rate of seeds. This protective effect afforded by mycosubtilin overproduction was also visualized by the significantly greater fresh weight of emerging seedlings treated with BBG100 compared to controls or seedlings inoculated with the wild-type strain.
Leclère
Valérie
V
Laboratory of Microbial Bioprocesses (LABEM), Polytech'Lille, University of Science and Technology of Lille, Avenue du Professeur Langevin, F-59655 Villeneuve d'Ascq Cedex, France.
Béchet
Max
M
Adam
Akram
A
Guez
Jean-Sébastien
JS
Wathelet
Bernard
B
Ongena
Marc
M
Thonart
Philippe
P
Gancel
Frédérique
F
Chollet-Imbert
Marlène
M
Jacques
Philippe
P
D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D000898:Antibiosis; D000935:Antifungal Agents / Q000378:metabolism / Q000494:pharmacology; D001412:Bacillus subtilis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D006461:Hemolysis; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D016982:Micrococcus luteus / Q000187:drug effects; D010572:Pest Control, Biological; D010935:Plant Diseases / Q000382:microbiology; D011401:Promoter Regions, Genetic; D011775:Pythium / Q000187:drug effects* / Q000254:growth & development; D015854:Up-Regulation
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D003470:Culture Media; D008074:Lipoproteins; C012448:mycosubtiline