Mating in Bacillus thuringiensis can induce plasmid integrative prophage J7W-1

Area of Science:

• Microbiology
• Bacteriology
• Molecular Biology

Background:

• Bacillus thuringiensis serovar israelensis (Bti) is a bacterium known for its plasmid transfer ability.
• Lysogenic conversion, where a phage integrates into the bacterial genome, can alter bacterial characteristics.
• Phage J7W-1 is a plasmid integrative phage capable of lysogenizing Bti.

Purpose of the Study:

• To investigate the phage induction response in a J7W-1 lysogen of Bti after conjugation with different bacterial strains.
• To explore the role of prophage repressors in regulating phage induction in various Bacillus species.

Main Methods:

• Lysogenization of B. thuringiensis serovar israelensis with plasmid integrative phage J7W-1.
• Conjugation experiments (mating) between the J7W-1 lysogen and various phage-insensitive and phage-sensitive bacterial strains.
• Observation and analysis of phage induction following mating.

Main Results:

• Phage induction occurred in the J7W-1 lysogen of Bti when mated with phage-insensitive strains (B. thuringiensis serovar thuringiensis, B. cereus, B. subtilis) and the phage-sensitive Bti strain.
• No phage induction was observed when mating with specific B. thuringiensis strains (AF101, serovar dendrolimus, serovar indiana) naturally associated with J7W-1 or related phages.
• Phage induction was observed in B. thuringiensis serovar aizawai, despite the presence of J7W-1 DNA homologous regions.

Conclusions:

• The absence of phage induction in certain B. thuringiensis strains suggests constitutive expression of the J7W-1 prophage repressor.
• The presence of homologous DNA regions does not guarantee phage induction, indicating complex regulatory mechanisms.
• This study provides insights into phage-host interactions and repressor function in Bacillus species.