Isolation And Regulation Mechanisms Study Of The Antibiotics In B. Amyloliquefaciens

The Bacillus amyloliquefaciens strains have potential to produce many antibiotics with a variety of structure. Principally, there are two different biosynthetic pathways for antibiotics peptides:(i) the non-ribosomal synthesis of peptides by large megaenzymes, the non-ribosomal peptide synthetases (NRPSs) and (ii) the ribosomal synthesis of linear precursor peptides that are subjected to post-translational modification and proteolytic processing. The B.amyloliquefaciens strain NK10.BAhjaWT, stored in our lab, could synthesize diverse secondary metabolites that have abilities against fungal or bacterial strains. Due to its potentials as antibiotics, it is important to isolate and identify antifungal or antimicrobial compounds.With the completion of sequencing of the Bacillus amyloliquefaciens FZB42 whole genome, the research about its capabilities of antifungal or antimicrobial came down to the molecular level. We screened a number of genes on antibiotics production in B.amyloliquefaciens strain NK10.BAhjaWT by Mini-Tn10 system. Then Real-time PCR, LacZ expression assay and Western blot were used to study regulation relationship involved these genes.We draw the following conclusions:1. In this research, we isolated an antimicrobial which had the molecular weight of 3399.8 D synthesized by B.amyloliquefaciens strain NK10.BAhjaWT. The gene sboA coding Sutilosin A, known antimicrobial has similar molecular weight to ours, was also found in this strain. We inferred that antimicrobial from B.amyloliquefaciens strain NK10.BAhjaWT was Subtilosin A.2. The mutant NK10.BAhjaWT-citB::Tn10 could decrease antifugal productivity through creating high level of DegU phosphorylation in B.amyloliquefaciens cells. But Sutilosin A only suppress G+bacterial, gene citB don't affect the production of Sutilosin A.3. The mutant NK10.BAhjaWT-purL::Tn10 had promotive effect in antimicrobial production. After further research, we found purL influenced TPP synthesization and the latter interacted with the global regulator AbrB to control Subtilosin A production.