Relationship between lysogeny, spontaneous induction, and transformation efficiencies in Bacillus subtilis

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Bacillus subtilis 168 transformation efficiency is often low.
• Lysogenic cells carrying phages ø105 or SPO2 exhibit reduced transformation rates.
• Competence, a state for DNA uptake, influences lysogenic cell physiology.

Purpose of the Study:

• To investigate the cause of low transformation efficiency in lysogenic Bacillus subtilis.
• To identify phage mutants that overcome this limitation.
• To understand the interaction between competence and prophage stability.

Main Methods:

• Comparing transformation efficiencies of lysogenic and non-lysogenic competent cells.
• Measuring spontaneous prophage induction rates in competent and non-competent cells.
• Isolating and characterizing phage mutants resistant to spontaneous induction.

Main Results:

• Competent lysogenic Bacillus subtilis cells show higher rates of spontaneous prophage induction.
• This induction leads to lytic phage replication and cell death, reducing transformant recovery.
• Mutants of phages ø105 and SPO2 resistant to spontaneous induction enabled higher transformation levels.

Conclusions:

• The physiological state of competence in Bacillus subtilis promotes prophage derepression.
• Prophage derepression in competent cells leads to cell death and loss of potential transformants.
• Phage mutants resistant to spontaneous induction can enhance transformation efficiency in lysogenic B. subtilis.