Plasmids and phages in Bifidobacterium longum

Area of Science:

• Microbiology
• Bacteriology
• Virology

Background:

• Bifidobacterium longum is a key probiotic bacterium.
• Bacteriophages (phages) are viruses that infect bacteria and can impact bacterial populations.
• The relationship between plasmids and phage production in B. longum is not well understood.

Purpose of the Study:

• To investigate phage production in Bifidobacterium longum strains.
• To determine if plasmids in B. longum are associated with phage induction.
• To characterize the morphology of induced bacteriophages.

Main Methods:

• Fourteen strains of Bifidobacterium longum were cultured.
• Bacterial strains were induced for phage production using UV irradiation and mitomycin C.
• Phage particles were observed using electron microscopy, and their dimensions were measured.
• Plasmid DNA was analyzed in the B. longum strains.

Main Results:

• Phage-like particles were successfully induced from four out of fourteen B. longum strains.
• Two of the phage-producing strains contained plasmids, while the other two did not.
• The induced phages exhibited head dimensions of 49-56 nm and tail lengths of 76-268 nm.
• No correlation was found between the presence of various plasmids and the induction of phages.

Conclusions:

• Bacteriophage production can be induced from certain Bifidobacterium longum strains.
• Plasmid carriage in B. longum does not appear to be a prerequisite for phage induction.
• The study characterized the morphology of induced B. longum phages and found no plasmid-phage correlation.