title: Investigation of the Antimicrobial Activity of Bacillus licheniformis Strains Isolated from Retail Powdered Infant Milk Formulae.
abstract: This study investigated the potential antimicrobial activity of ten Bacillus licheniformis strains isolated from retail infant milk formulae against a range of indicator (Lactococcus lactis, Lactobacillus bulgaricus and Listeria innocua) and clinically relevant (Listeria monocytogenes, Staphylococcus aureus, Streptococcus agalactiae, Salmonella Typhimurium and Escherichia coli) microorganisms. Deferred antagonism assays confirmed that all B. licheniformis isolates show antimicrobial activity against the Gram-positive target organisms. PCR and matrix-assisted laser desorption ionization time-of-flight mass spectrometry analyses indicated that four of the B. licheniformis isolates produce the bacteriocin lichenicidin. The remaining six isolates demonstrated a higher antimicrobial potency than lichenicidin-producing strains. Further analyses identified a peptide of ~1,422 Da as the most likely bioactive responsible for the antibacterial activity of these six isolates. N-terminal sequencing of the ~1,422 Da peptide from one strain identified it as ILPEITXIFHD. This peptide shows a high homology to the non-ribosomal peptides bacitracin and subpeptin, known to be produced by Bacillus spp. Subsequent PCR analyses demonstrated that the six B. licheniformis isolates may harbor the genetic machinery needed for the synthesis of a non-ribosomal peptide synthetase similar to those involved in production of subpeptin and bacitracin, which suggests that the ~1,422 Da peptide might be a variant of subpeptin and bacitracin.
authors.affiliation: Department of Microbiology, University College Cork, Cork, Ireland, avalordvet@gmail.com.
authors.forename: Avelino
authors.initials: A
authors.lastname: Alvarez-Ordóñez
authors.forename: Máire
authors.initials: M
authors.lastname: Begley
authors.forename: Tanya
authors.initials: T
authors.lastname: Clifford
authors.forename: Thérèse
authors.initials: T
authors.lastname: Deasy
authors.forename: Kiera
authors.initials: K
authors.lastname: Considine
authors.forename: Paula
authors.initials: P
authors.lastname: O'Connor
authors.forename: R Paul
authors.initials: RP
authors.lastname: Ross
authors.forename: Colin
authors.initials: C
authors.lastname: Hill
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D001407:Bacillus / Q000145:classification / Q000302:isolation & purification* / Q000502:physiology*; D001430:Bacteriocins / Q000096:biosynthesis / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D005506:Food Contamination / Q000517:prevention & control; D005516:Food Microbiology; D041943:Infant Formula / Q000382:microbiology*; D007778:Lactobacillus / Q000378:metabolism; D013294:Lactococcus lactis / Q000378:metabolism; D008087:Listeria / Q000378:metabolism; D008089:Listeria monocytogenes / Q000378:metabolism; D012486:Salmonella typhimurium / Q000378:metabolism; D013211:Staphylococcus aureus
chemical_list: D000890:Anti-Infective Agents; D001430:Bacteriocins