Related Experiment Videos
A novel phage genome integrated into a plasmid in Bacillus thuringiensis strain AF101
1Institute of Biological Control, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Abstract:
Bacillus thuringiensis strain AF101 possesses a single plasmid (pAF101) with a molecular size of 42 MDa (69 kb). During plasmid curing experiments in strain AF101, we found that a phage (J7W-1) was induced by ethidium bromide treatment. Moreover, the phage genome (48 kb) hybridized only with pAF101 on a Southern blot of the DNA of a cleared lysate prepared from strain AF101. Comparison of the restriction patterns of pAF101 and J7W-1 phage DNA revealed that pAF101 contains not only the entire phage DNA but also a plasmid-specific DNA region. These results indicate that the J7W-1 genome has been stably integrated into pAF101 in strain AF101. Integration of the J7W-1 genome into a plasmid was also observed after phage infection of the type strain of B. thuringiensis subsp. israelensis.
Insights
Bacillus thuringiensis strain AF101 harbors a plasmid (pAF101) that contains the integrated genome of the J7W-1 phage. This phage genome integration into a plasmid was also observed in other Bacillus thuringiensis strains.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Bacillus thuringiensis (Bt) is a Gram-positive bacterium known for its insecticidal properties.
- Bt strains often harbor plasmids that carry genes for toxins and other functions.
- Phages can infect bacteria and integrate their genomes into the host's DNA.
Purpose of the Study:
- To investigate the nature of a plasmid (pAF101) in Bacillus thuringiensis strain AF101.
- To determine the relationship between the plasmid and an induced phage (J7W-1).
- To explore the phenomenon of phage genome integration into plasmids in B. thuringiensis.
Main Methods:
- Plasmid curing experiments using ethidium bromide.
- Phage induction and isolation.
- Southern blot hybridization to analyze DNA.
- Restriction pattern comparison of plasmid and phage DNA.
Main Results:
- Ethidium bromide treatment induced the J7W-1 phage from B. thuringiensis strain AF101.
- The J7W-1 phage genome hybridized exclusively with pAF101 DNA.
- pAF101 contains the complete J7W-1 phage genome and a plasmid-specific region.
- Phage genome integration into a plasmid was also observed in B. thuringiensis subsp. israelensis.
Conclusions:
- The J7W-1 phage genome is stably integrated into the pAF101 plasmid in B. thuringiensis strain AF101.
- This integration represents a novel mechanism of phage-plasmid interaction.
- Phage genome integration into plasmids may occur in other B. thuringiensis strains.