Plant-made Salmonella bacteriocins salmocins for control of Salmonella pathovars

Salmonella enterica causes an estimated 1 million illnesses in the United States each year, resulting in 19,000 hospitalizations and 380 deaths, and is one of the four major global causes of diarrhoeal diseases. No effective treatments are available to the food industry. Much attention has been given to colicins, natural non-antibiotic proteins of the bacteriocin class, to control the related pathogen Escherichia coli. We searched Salmonella genomic databases for colicin analogues and cloned and expressed in plants five such proteins, which we call salmocins. Among those, SalE1a and SalE1b were found to possess broad antimicrobial activity against all 99 major Salmonella pathovars. Each of the two salmocins also showed remarkably high potency (>10⁶ AU/µg recombinant protein, or >10³ higher than colicins) against major pathogenic target strains. Treatment of poultry meat matrices contaminated with seven key pathogenic serovars confirmed salmocin efficacy as a food safety intervention against Salmonella.