Presentation Information
[P01-090]Enhancement of the biosynthesis of secondary metabolites in Streptomyces sp. strain TUA-HK1GM by sodium chloride
○Sachiko Masaki1, Sho Ogaki2, Aiko Teshima2, Ryosuke Unno1, Morio Ishikawa1, Taifo Mahmud3, Kenji Arakawa2, Toshihiro Suzuki1 (1. Department of Fermentation Science and Technology, Graduate School of Applied Bioscience, Tokyo University of Agriculture (Japan), 2. Graduate School of Integrated Science for Life, Hiroshima University (Japan), 3. Department of Pharmaceutical Sciences, Oregon State University (USA))
Keywords:
Streptomyces,oligomycin,7-deoxypactamycin,secondary metabolites,sodium chloride
Genus Streptomyces produces a wide variety of antibiotics and other bioactive compounds as secondary metabolites. However, the discovery rate of novel actinomycetes, including Streptomyces, and antibiotics they produce is decreasing. Therefore, diverse environments other than soil, the traditional source of isolation, are now studied as new sources of actinomycetes and novel antibiotics. These strains may have different metabolic features from soil-derived Streptomyces.
To explore novel actinomycetes, antibiotics, and the mechanisms of antibiotic production, we focused on a salt-containing fermented fish brine known as “kusaya gravy”, which exhibits antimicrobial activities, as a new isolation source. From kusaya gravy, we successfully isolated several Streptomyces strains [1]. Among them, Streptomyces sp. strain TUA-HK1GM showed high salt tolerance and harbored a large genome of approximately 11 Mbp, including approximately 40 putative secondary metabolite biosynthetic gene clusters. Based on these characteristics, we investigated the antibiotic production of the strain.
First, strain TUA-HK1GM was cultured on ISP2 medium, where it exhibited strong antifungal activity and the active principle was identified as oligomycin B. Subsequently, the strain was cultured on ISP2-3N medium (ISP2 medium containing 3% NaCl), since it was isolated from a hypersaline environment. As a result, we observed antibacterial activities in addition to antifungal activity, and identified the compounds responsible for these new activities as 7-deoxypactamycin and previously unknown pactamycin analogues. Significant production of oligomycin A and an increase in oligomycin B were also observed. Quantitative analysis revealed that the addition of 3% NaCl during cultivation increased the yields of these antibiotics in a NaCl exposure duration-dependent manner. Furthermore, we investigated the effect of NaCl on the production of secondary metabolites beyond antifungal and antibacterial compounds. We analyzed culture extracts from ISP2 and ISP2-3 media through LC-MS and performed differential analysis using OPLS-DA (Orthogonal Projections to Latent Structures Discriminant Analysis). Of the 855 detected compounds, 538 showed at least a 5-fold increase in peak intensities in the ISP2-3N medium compared with the ISP2 medium. These results demonstrate that addition of 3% NaCl activates and enhances the production of various secondary metabolites, including antibiotics, in this strain. This suggests that NaCl supplementation is a simple and effective strategy to enhance antibiotic production. Further studies are currently underway to elucidate how NaCl enhances antibiotic production in this strain.
[1] Masaki S et al., J. Gen. Appl. Microbiol., 2024;70:147–51
To explore novel actinomycetes, antibiotics, and the mechanisms of antibiotic production, we focused on a salt-containing fermented fish brine known as “kusaya gravy”, which exhibits antimicrobial activities, as a new isolation source. From kusaya gravy, we successfully isolated several Streptomyces strains [1]. Among them, Streptomyces sp. strain TUA-HK1GM showed high salt tolerance and harbored a large genome of approximately 11 Mbp, including approximately 40 putative secondary metabolite biosynthetic gene clusters. Based on these characteristics, we investigated the antibiotic production of the strain.
First, strain TUA-HK1GM was cultured on ISP2 medium, where it exhibited strong antifungal activity and the active principle was identified as oligomycin B. Subsequently, the strain was cultured on ISP2-3N medium (ISP2 medium containing 3% NaCl), since it was isolated from a hypersaline environment. As a result, we observed antibacterial activities in addition to antifungal activity, and identified the compounds responsible for these new activities as 7-deoxypactamycin and previously unknown pactamycin analogues. Significant production of oligomycin A and an increase in oligomycin B were also observed. Quantitative analysis revealed that the addition of 3% NaCl during cultivation increased the yields of these antibiotics in a NaCl exposure duration-dependent manner. Furthermore, we investigated the effect of NaCl on the production of secondary metabolites beyond antifungal and antibacterial compounds. We analyzed culture extracts from ISP2 and ISP2-3 media through LC-MS and performed differential analysis using OPLS-DA (Orthogonal Projections to Latent Structures Discriminant Analysis). Of the 855 detected compounds, 538 showed at least a 5-fold increase in peak intensities in the ISP2-3N medium compared with the ISP2 medium. These results demonstrate that addition of 3% NaCl activates and enhances the production of various secondary metabolites, including antibiotics, in this strain. This suggests that NaCl supplementation is a simple and effective strategy to enhance antibiotic production. Further studies are currently underway to elucidate how NaCl enhances antibiotic production in this strain.
[1] Masaki S et al., J. Gen. Appl. Microbiol., 2024;70:147–51
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