Bacillus strains isolated from indoor dusts produced antimicrobial lipopeptides

Raimo Mikkola*, Aino Andersson, Heidi Salonen

*Corresponding author for this work

Research output: Contribution to conferenceAbstractScientificpeer-review


Bacterial colonies from indoor dusts were screened for production of bioactivesubstances. Colonies antagonistic to the growth of other microbes on cultureplates, were isolated and extracted with methanol and investigated for theirantimicrobial and cytotoxic effects. The first category strains were isolatedfrom five different buildings over a five-year period. The strains hadidentical DNA fingerprinting ribopatterns and were identified as Bacillusamyloliquefaciens. The B. amyloliquefaciens strains inhibited the growth ofChaetomium globosum, B. megaterium, Mycobacterium murale, Sphingomonas aurantiacaand Ureibacillus thermosphaericus. B. amyloliquefaciens strains producedthermostable methanol-soluble antimicrobial agents identified by LC-MS / MS assurfactin, fengycin, bacillomycin D and amylosin lipopeptides. Amylosin wastoxic to somatic cells and boar sperm cells and exhibited high antimicrobialactivity. Tested fengycin and surfactin were >10 times less toxic thanamylosin. The B. amyloliquefaciens type strains DSM 7 and IAM 1521 were not antimicrobialand biocontrol strain FBZ42 was non-toxic to boar sperm. The second and thirdcategory of Bacillus strains inhibited the growth of Penicillium strains butwere not sperm toxic. LC-MS/MS analyses showed that both second and thirdcategory strain(s) produced fengycin and surfactin, while bacillomycin Lclipopeptides were produced only by the third category strain. Bacilli producingbioactive lipopeptides have been isolated from different environments, but tothe best of our knowledge, no strains producing both the three lipopeptidefamilies and amylosin have been previously reported in buildings. Surfactantsof cleaning agents damages mammalian cell membranes in the same way as toxic lipopeptidebiosurfactants. Therefore, toxic lipopeptides from indoor microbes or detergentmay impair indoor air quality.

Original languageEnglish
Number of pages1
Publication statusPublished - Sept 2022
MoE publication typeNot Eligible
EventBiosurfactants International Conference - University of Hohenheim, Stuttgart, Germany
Duration: 27 Sept 202230 Sept 2022


ConferenceBiosurfactants International Conference


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