Induction of stringent response by streptomycin in Bacillus subtilis cells

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Physiology

Background:

• The stringent response is a global regulatory mechanism in bacteria crucial for survival under stress.
• Bacillus subtilis is a model organism for studying bacterial physiology and stress responses.

Purpose of the Study:

• To investigate the induction of the stringent response in Bacillus subtilis by streptomycin.
• To examine the effect of tetracyclines on the streptomycin-induced stringent response.

Main Methods:

• Induction of stringent response in Bacillus subtilis vegetative cells using streptomycin.
• Comparison of stringent (BR16S) and relaxed (BR16R) strains.
• Assessment of stable RNA synthesis and guanosine polyphosphate (pppGpp and ppGpp) levels.
• Pretreatment of stringent cells with tetracyclines before streptomycin exposure.

Main Results:

• Streptomycin successfully induced the stringent response in BR16S cells, characterized by repressed stable RNA synthesis and transient synthesis of pppGpp and ppGpp.
• The isogenic relaxed strain (BR16R) did not exhibit these phenomena under identical conditions.
• Tetracyclines did not induce the stringent response independently.
• Pretreatment with tetracyclines released the stringent response to streptomycin in BR16S cells.

Conclusions:

• Streptomycin is an effective inducer of the stringent response in Bacillus subtilis vegetative cells.
• The stringent response is dependent on the genetic background (stringent vs. relaxed strains).
• Tetracyclines interfere with and can prevent the streptomycin-induced stringent response, suggesting a complex interplay between these antibiotics and bacterial stress pathways.