Plasmids Can Shift Bacterial Morphological Response against Antibiotic Stress

Area of Science:

• Microbiology
• Bacterial Morphology
• Antibiotic Resistance

Background:

• Bacterial cell filamentation is a survival mechanism under stress.
• Plasmids can provide advantageous traits like antibiotic resistance.
• The impact of plasmids on bacterial morphological responses to antibiotics is unclear.

Purpose of the Study:

• To investigate how plasmids influence bacterial filamentation under antibiotic stress.
• To elucidate the molecular mechanisms behind plasmid-mediated morphological changes.
• To understand the role of plasmids in bacterial adaptation to antibiotics.

Main Methods:

• Exposure of plasmid-free and plasmid-bearing bacteria to sub-inhibitory antibiotic concentrations (ciprofloxacin, cephalexin).
• Analysis of DNA damage, cell division inhibitor sulA expression, SOS response, and efflux pump activity.
• Investigation of the plasmid-encoded parDE toxin-antitoxin module.

Main Results:

• Plasmid-free cells exhibited filamentation and asymmetrical cell division, unlike plasmid-bearing cells.
• Higher sulA expression was observed in plasmid-free cells.
• Plasmid carriage reduced DNA damage, increased efflux pump activity, and enhanced antibiotic tolerance.

Conclusions:

• Plasmids confer innate defenses against antibiotics, altering bacterial morphology.
• The parDE module on plasmids plays a key role in mediating stress responses and morphological changes.
• Plasmids significantly impact bacterial evolution and survival in antibiotic-stressed environments.