Limitation of nutrients stimulates musty odor production by Streptomyces sp. isolated from a tropical environment

J Gen Appl Microbiol. 2021 Jul 31;67(3):92-99. doi: 10.2323/jgam.2020.08.001. Epub 2021 Feb 27.


Musty odor production by actinomycetes is usually related to the presence of geosmin and 2-methylisoborneol (2-MIB), which are synthesized by enzymes encoded by the geoA and tpc genes, respectively. Streptomyces spp. strain S10, which was isolated from a water reservoir in Malaysia, has the ability to produce geosmin when cultivated in a basal salt (BS) solid medium, but no 2-MIB production occurred during growth in BS medium. Strain S10 could produce higher levels of geosmin when the phosphate concentration was limited to 0.05 mg/L, with a yield of 17.53 ± 3.12 ✕ 105 ng/L, compared with growth in BS medium. Interestingly, 2-MIB production was suddenly detected when the nitrate concentration was limited to 1.0 mg/L, with a yield of 1.4 ± 0.11 ✕ 105 ng/L. Therefore, it was concluded that phosphate- and nitrate-limiting conditions could induce the initial production of geosmin and 2-MIB by strain S10. Furthermore, a positive amplicon of geoA was detected in strain S10, but no tpc amplicon was detected by PCR analysis. Draft genome sequence analysis showed that one open reading frame (ORF) contained a conserved motif of geosmin synthase with 95% identity with geoA in Streptomyces coelicolor A3 (2). In the case of the tpc genes, it was found that one ORF showed 23% identity to the known tpc gene in S. coelicolor A3(2), but strain S10 lacked one motif in the N-terminus.

Keywords: 2-methylisoborneol; Streptomyces; geosmin; nutrient limitation.

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Camphanes / metabolism
  • Culture Media / chemistry
  • Genome, Bacterial / genetics
  • Malaysia
  • Naphthols / metabolism
  • Nitrates / analysis
  • Nutrients / deficiency*
  • Odorants* / analysis
  • Phosphates / analysis
  • Streptomyces / isolation & purification
  • Streptomyces / metabolism*
  • Water Microbiology


  • Bacterial Proteins
  • Camphanes
  • Culture Media
  • Naphthols
  • Nitrates
  • Phosphates
  • 2-methylisoborneol
  • geosmin