[Thermosensitivity of naphthalene biodegradation plasmids]

Area of Science:

• Microbiology
• Molecular Biology
• Environmental Science

Background:

• Pseudomonas aeruginosa harbors plasmids encoding naphthalene and salicylic acid catabolism.
• Plasmid stability is crucial for maintaining biodegradation capabilities.
• Thermosensitivity of plasmids can impact bacterial growth and function.

Purpose of the Study:

• To investigate the functional expression and stability of naphthalene biodegradation plasmids (NAH, pBS2, pBS3, NPL-41) in Pseudomonas aeruginosa PAO.
• To determine the thermosensitivity and growth inhibitory effects of these plasmids at elevated temperatures.

Main Methods:

• Studying functional expression of catabolic systems.
• Assessing plasmid stability at varying temperatures.
• Monitoring bacterial growth and cell morphology under thermal stress.
• Selecting plasmid-free clones at elevated temperatures.

Main Results:

• Naphthalene catabolism plasmids (NAH, pBS2, pBS3, NPL-41) exhibit thermosensitivity.
• Plasmid instability and growth inhibition occurred at 41-42°C.
• NPL-41 and pBS3 strongly inhibited growth, while NAH and pBS2 showed weak inhibition.
• Plasmid loss facilitated normal growth at elevated temperatures, enabling selection of cured strains.

Conclusions:

• Plasmid-encoded naphthalene biodegradation systems are thermosensitive.
• Elevated temperatures can lead to plasmid elimination and altered bacterial morphology.
• The thermosensitivity of these plasmids provides a method for selecting plasmid-free Pseudomonas aeruginosa strains.
• Plasmid-mediated growth inhibition at high temperatures should be considered in Pseudomonas taxonomy.