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

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

JOURNAL OF MASS SPECTROMETRY

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2022

1076-5174

In this work two Bacillus strains isolated from honey (Bacillus subtilis subsp. subtilis C4;access code HQ828992) and from a waste of an artisanal tannery (Bacillusamyloliquefaciens B31; access code KP893752), were evaluated in order to determine theirantibacterial activity against five enteropathogenic Escherichia coli strains. The number ofviable cultivable cells of the different strains of E. coli analyzed was determined by platecount. The crude cell free supernatants of both Bacillus strains exerted anti-E. coliactivities, while only the lipopeptide fraction of B31 had significant E. coli inhibition. Thelipopeptides produced by the Bacillus were analyzed using matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS). The analysis was conducted combining theprofiles (fingerprints) of the lipopeptides mixture and the individual lipopeptidefragmentation (MS/MS mode), both obtained from the same lipopeptides mixture sample,for higher output. Data obtained from C4 and B31 revealed that surfactin homologues werethe most abundant lipopeptides produced by both strains studied. Additionally, kurstakin,iturin and fengycin homologues were detected. Using the MS/MS mode, it wasdemonstrated that isobar compounds belonging to different families were produced by eachBacillus strain (e.g, C-16 bacillomycin D was detected in B31 samples, meanwhile C-15iturin C was detected in C4). Tandem mass spectrometry MS/MS analysis contributed withrelevant information about the type of lipopeptides that the studied Bacillus strainssynthesize.