Identification, Comparison, and Transfer of the pxo Gene between Members of Bacilli Species

Aim: Bacillus anthracis causes anthrax in which the pxo gene and its associated plasmids, pXOP1and pXO2, encode toxin and capsule proteins, both of which are involved in the pathogenicity of anthrax. The possibility of transferring the pxo gene to other bacilli has recently been shown. The main aims of this study were to identify and compare the frequencies of the pxo gene in isolated bacilli members. The study examined possible pxo gene transfer from B. anthracis to other closely related members of the genus Bacillus. The findings presented here may be useful in the study of vaccination.

Study Design: The study design was cross-sectional and descriptive. Sixty-five soil samples were collected from different geographical regions in Iran.

Place and duration of study: The study was conducted in many provinces in Iran over several months. Samples were analyzed at the Mashhad University of Medical Sciences.

Methodology: Organisms were isolated from the soil, and the isolation of pXO plasmid was performed. Presence of the pXO1 plasmid was confirmed by agarose gel electrophoresis. Isolated proteins from each bacillus were examined by SDS-PAGE. The limits of proteins encoded by the pxo gene were specifically located and data were statistically analyzed using excel.

Results: Results showed that 13 samples out of 38 bacilli contained the plasmid of interest and protein bands related to proteins coded by the pxo gene.

Conclusion: We have determined that the pXO1 plasmid has been transferred from B. anthracis to 13 other isolates of B. cereus group members in different regions in Iran. No transfer of the pXO2 plasmid was observed. This was apart from the identification of the pxo gene and its plasmids in different members of bacilli.