There has been a resurgent interest in the use of bacteriophages or their gene products to control bacterial pathogens as alternatives to currently used antibiotics, according to Bruce S. Seal of the R.B. Russell Agricultural Research Center in Athens, Georgia.

In a paper presented at the 'Tomorrow’s Poultry: Sustainability and Safety Symposium' at the Poultry Science Association's annual meeting in Athens in July 2012 and published in Poultry Science, he explained that Clostridium perfringens is a gram-positive, spore-forming anaerobic bacterium that plays a significant role in human foodborne disease as well as non-foodborne human, animal, and avian diseases.

Countries that have complied with the ban on antimicrobial growth promoters in feeds have reported increased incidences of C. perfringens-associated diseases in poultry. To address these issues, new antimicrobial agents, putative lysins encoded by the genomes of bacteriophages, are being identified in the Athens laboratory.

Poultry intestinal material, soil, sewage and poultry processing drainage water were screened for virulent bacteriophages that could lyse C. perfringens and produce clear plaques in spot assays.

Bacteriophages were isolated that had long non-contractile tails, members of the family Siphoviridae, and with short non-contractile tails, members of the family Podoviridae.

Several bacteriophage genes were identified that encoded N-acetylmuramoyl-l-alanine amidases, lysozyme-endopeptidases, and a zinc carboxypeptidase domain that has not been previously reported in viral genomes.

Putative phage lysin genes (ply) were cloned and expressed in Escherichia coli. The recombinant lysins were amidases capable of lysing both parental phage host strains of C. perfringens as well as other strains of the bacterium in spot and turbidity reduction assays but did not lyse any clostridia beyond the species.

Consequently, according to Seal, bacteriophage gene products could eventually be used to target bacterial pathogens, such as C. perfringens via a species-specific strategy in order to control animal and human diseases without having deleterious effects on beneficial probiotic bacteria.

Reference

^{Seal B.S. 2013. Characterization of bacteriophages virulent for Clostridium perfringens and identification of phage lytic enzymes as alternatives to antibiotics for potential control of the bacterium. Poult. Sci. 92(2):526-533. doi: 10.3382/ps.2012-02708}

February 2013