Transposon mutagenesis of antagonistic bacterium acillus cereus C1L and the cloning of genes related to ntifungal activity
Date Issued
2008
Date
2008
Author(s)
Huang, Ru-Yin
Abstract
Bacillus cereus C1L, an antagonistic bacterium, was originally isolated from the rhizosphere of Fomorsa lily. In order to identify the genes related to the antagonistic ability of B. cereus C1L, a transponson insertion mutant library was constructed. Totally, 850 mutants were obtained. Alternaria brassicicola and Alternaria longipes were used in mutant screening on potato dextrose agar and a mutant, M-902, with significant decrease on antifungal activity was selected. M-902 loses its inhibitory activity against mycelial growth of A. brassicicola, A. longipes, Botrytis cinerea, and Botrytis elliptica ; in addition, the culture supernatant of M-902 decreases spore germination rate. Sequence analysis revealed that the Tn917ac1 was inserted into a plasmid pC1L8 of B. cereus C1L wild-type strain. Southern blot analysis showed a band shift of pC1L8 of B. cereus M-902. The Tn917ac1 insertion site was located downstream a putative promoter of open reading frames-orf1 and orf2。These two ORFs may constitute a two-gene operon. In a complementay test using A. brassicicola as the test fungus, the vector containing predicted promoter, orf1 and orf2, or orf2 singly showed a partial recovery of the inhibition on conidial germination, but orf1 singly could not recover the inhibition on conidial germination. Thus, orf 2 related to antibiotic production of strain C1L was presumed.
Subjects
transposon mutagenesis, Bacillus cereus, antifungal activity, biocontrol bacterium, molecular cloning
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