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

Abstract

Musty odor production by actinomycetes is usually related to the presence of geosmin and 2methylisoborneol (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 × × × × × 10 5 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 × × × × × 10 5 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.

Temporal variation of 2‐MIB and geosmin production by Pseudanabaena galeata and Phormidium ambiguum exposed to high‐intensity light

“…The stress-induced production of 2-MIB and GSM in cyanobacteria has been reported in previous studies (Shen et al, 2021;Shudirman et al, 2021). Also, in the present study, the production of 2-MIB and GSM was elevated at the onset of high-intensity light.…”

“…Cyanobacteria can morphologically and physiologically adjust to prevailing environmental conditions, and these adjustments can influence the production of odorous compounds. Based on prior evidence, cyanobacterial 2‐MIB and GSM production can be elevated by unfavorable conditions, such as nutrient limitations and temperature (Shen et al, 2021; Shudirman et al, 2021). However, whether extreme conditions, such as high temperature and extreme light intensity, influence the formation of odorous compounds is unknown.…”