Bacillus amyloliquefaciens strains isolated from moisture-damaged buildings produced surfactin and a substance toxic to mammalian cells

R Mikkola*, MA Andersson, P Grigoriev, VV Teplova, NEL Saris, FA Rainey, MS Salkinoja-Salonen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review


Fungicidic Bacillus amyloliquefaciens strains isolated from the indoor environment of moisture-damaged buildings contained heat-stable, methanol-soluble substances that inhibited motility of boar spermatozoa within 15 min of exposure and killed feline lung cells in high dilution in 1 day. Boar sperm cells lost motility, cellular ATP, and NADH upon contact to the bacterial extract (0.2 mug dry wt/ml). Two bioactive substances were purified from biomass of the fungicidal isolates. One partially characterized substance, 1,197 Da, was moderately hydrophobic and contained leucine, proline, serine, aspartic acid, glutamic acid and tyrosine, in addition to chromophore(s) absorbing at 365 nm. In boar sperm and human neural cells (Paju), the compound depolarized the transmembrane potentials of mitochondria (DeltaPsi(m)) and the plasma membrane (DeltaPsi(p)) after a 20-min exposure and formed cation-selective channels in lipid membranes, with a selectivity K+:Na+:Ca2+ of 26:15:3.5. The other substance was identified as a plasma-membrane-damaging lipopeptide surfactin. Plate-grown biomass of indoor Bacillus amyloliquefaciens contained ca. 7% of dry weight of the two substances, 1,197 Da and surfactin, in a ratio of 1:6 (w:w). The in vitro observed simultaneous collapse of both cytosolic and mitochondrial ATP in the affected mammalian cell, induced by the 1,197-Da cation channel, suggests potential health risks for occupants of buildings contaminated with such toxins.

Original languageEnglish
Pages (from-to)314-323
Number of pages10
JournalArchives of Microbiology
Issue number4
Publication statusPublished - Apr 2004
MoE publication typeA1 Journal article-refereed


  • Bacillus amyloliquefaciens
  • black lipid membrane
  • cation channel
  • ionophore
  • membrane-damage
  • mitochondria
  • moisture-damaged building
  • plasma membrane
  • surfactin
  • toxin
  • PORE
  • AIR


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