Functionality of Tn916 in Paenibacillus larvae.

Area of Science:

• Microbiology
• Bacterial Genetics
• Horizontal Gene Transfer

Background:

• Paenibacillus larvae is an important honeybee pathogen.
• Conjugative transposons facilitate the spread of antibiotic resistance genes.
• Understanding Tn916 mobility in P. larvae is crucial for controlling resistance.

Purpose of the Study:

• To investigate the functionality and transferability of the conjugative transposon Tn916 in Paenibacillus larvae.
• To assess the stability and insertion patterns of Tn916 and its derivative Tn916ΔE in P. larvae.
• To determine the potential for interspecies and intraspecies transfer of Tn916 within Paenibacillus.

Main Methods:

• Conjugative transfer experiments using defined donor and recipient strains.
• Expression analysis of antibiotic resistance genes (tetracycline and erythromycin).
• Southern hybridization for transposon insertion site analysis and copy number determination.

Main Results:

• Tn916 demonstrated functional expression of tetracycline resistance and conjugative transfer in P. larvae.
• Tn916ΔE also conferred erythromycin resistance, indicating its functionality.
• Both interspecies and intraspecies transfer of Tn916 and Tn916ΔE were observed.
• Southern hybridization revealed random chromosomal insertion of Tn916, with evidence of hot spots and predominantly single-copy insertions.
• Multiple copies of Tn916 and Tn916ΔE could coexist in the P. larvae genome.
• Tn916 and Tn916ΔE were stably maintained in P. larvae without antibiotic selection.

Conclusions:

• The conjugative transposon Tn916 is a mobile genetic element capable of functional expression and transfer in Paenibacillus larvae.
• Tn916 can transfer both within and between Paenibacillus species, contributing to the dissemination of antibiotic resistance.
• The stable maintenance and potential for multiple-copy integration suggest Tn916 can persist and spread within bacterial populations.