The mitochondrial toxin produced by Streptomyces griseus strains isolated from an indoor environment is valinomycin

MA Andersson*, R Mikkola, RM Kroppenstedt, FA Rainey, J Peltola, J Helin, K Sivonen, MS Salkinoja-Salonen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Actinomycete isolates from indoor air and dust in water-damaged schools and children's day care centers were tested for toxicity by using boar spermatozoa as an indicator. Toxicity was detected in extracts of four strains which caused a loss of sperm motility, and the 50% effective concentrations (EC50) were 10 to 63 ng (dry weight) mi of extended boar semen(-1). The four strains were identified as Streptomyces griseus strains by 16S ribosomal DNA and chemotaxonomic methods. The four S. griseus strains had similar effects on sperm cells, including loss of motility and swelling of mitochondria, but we observed no loss of plasma membrane integrity or depletion of cellular ATP, None of the effects was observed with sperm cells exposed to extracts of other indoor actinomycete isolates at concentrations of greater than or equal to 5,000 to 72,000 ng ml(-1). The toxin was purified from all four strains and was identified as a dodecadepsipeptide, and the fragmentation pattern obtained by tandem mass spectrometry was identical to that of valinomycin, Commercial valinomycin had effects in sperm cells that were identical to the effects of the four indoor isolates of S, griseus. The EC50 of purified toxin from the S, griseus strains were 1 to 3 ng ml of extended boar semen(-1), and the EC50 of commercial valinomycin was 2 ng ml of extended boar semen(-1). To our knowledge, this is the first report of the presence of ionophoric toxin producers in an indoor environment and the first report of valinomycin-producing strains identified as S, griseus.

Original languageEnglish
Pages (from-to)4767-4773
Number of pages7
JournalApplied and Environmental Microbiology
Volume64
Issue number12
Publication statusPublished - Dec 1998
MoE publication typeA1 Journal article-refereed

Keywords

  • BACILLUS-CEREUS
  • MICROORGANISMS
  • MYCOTOXINS
  • BACTERIA

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