moldi

• Antibiotics


  Potent small molecules that can inhibit essential cellular processes and confer a competitive advantage to the producing organism
• Streptomycin


  • An aminoglycoside antibiotic produced by Streptomyces bacteria
• Streptomycin production


  1. Formation of a glucose-derived precursor

  2. Modification by various enzymes, including glycosyltransferases, methyltransferases, and oxidoreductases

  3. Catalysis by StreptidineStreptomycin 6-kinase (StrS6K) to form the streptidine moiety
• Biosynthetic pathway


  Complex pathway with multiple enzymatic steps, encoded by a gene cluster spanning over 25 kilobases in the Streptomyces genome
• Biosynthetic pathway regulation


  Tightly regulated by pathway-specific regulatory genes, which respond to environmental cues and nutrient availability
• Streptomycin mechanism of action

  Binds to the 30S subunit of the bacterial ribosome, interfering with protein synthesis and causing mistranslation of mRNA
• Streptomycin resistance mechanisms in Streptomyces

  • Ribosomal mutations
  • Enzymatic inactivation
  • Efflux pumps
• Self-resistance mechanisms


  Allow Streptomyces species to tolerate the high concentrations of streptomycin produced during antibiotic biosynthesis, preventing self-toxicity
• Ecological role of streptomycin

  • Provides a competitive advantage by inhibiting the growth of other bacteria and fungi, reducing competition for nutrients and ecological niches
  • Production is often triggered by environmental cues, serving as a defensive strategy and a means of resource competition
  • Can act as a signaling molecule, modulating gene expression and behavior in both the producing Streptomyces species and other microorganisms
• Agricultural use of streptomycin

  • Used as a bactericide to control bacterial diseases in plants, such as fire blight in apple and pear trees
• Medical use of streptomycin

  • Used to treat tuberculosis, a deadly infectious disease caused by Mycobacterium tuberculosis
• The widespread use of streptomycin in both agriculture and medicine has contributed to the emergence of antibiotic resistance