Antibacterial activity against enterovirulent Escherichia coli strains from Bacillus amyloliquefaciens B31 and Bacillus subtilis subsp. subtilis C4: MALDI‐TOF MS profiling and MALDI TOF/TOF MS structural analysis on lipopeptides mixtures

HUARACHI, SERGIO FERNANDO; PETROSELLI, GABRIELA; ERRA-BALSELLS, ROSA; AUDISIO, MARCELA CARINA

JOURNAL OF MASS SPECTROMETRY

JOHN WILEY & SONS LTD

Año: 2022 vol. 57 p. 1 - 10

1076-5174

AbstractIn this work, two Bacillus strains isolated from honey (Bacillus subtilis subsp. subtilisC4; access code HQ828992) and from a waste of an artisanal tannery (Bacillus amyloliquefaciensB31; access code KP893752) were evaluated in order to determine theirantibacterial activity against five enteropathogenic Escherichia coli strains. The numberof viable cultivable cells of the different strains of E. coli analyzed was determinedby plate count. The crude cell-free supernatants of both Bacillus strains exerted anti-E. coli activities, whereas only the lipopeptide fraction of B31 had significant E. coliinhibition. The lipopeptides produced by the Bacillus were analyzed using matrixassistedlaser desorption–ionization mass spectrometry (MALDI MS). The analysiswas conducted combining the profiles (fingerprints) of the lipopeptides mixture andthe individual lipopeptide fragmentation (tandem mass spectrometry [MS/MS]mode), both obtained from the same lipopeptides mixture sample, for higher output.Data obtained from C4 and B31 revealed that surfactin homologues were the mostabundant lipopeptides produced by both strains studied. Additionally, kurstakin,iturin, and fengycin homologues were detected. Using the MS/MS mode, it was demonstratedthat isobar compounds belonging to different families were produced byeach Bacillus strain (e.g., C-16 bacillomycin D was detected in B31 samples, meanwhileC-15 iturin C was detected in C4). MS/MS analysis contributed with relevantinformation about the type of lipopeptides synthesized by Bacillus strains studied inthis work.KEYWORDSBacillus, Escherichia coli, fingerprint, lipopeptides, MALDI TOF/TOF MS