Plant-made Salmonella bacteriocins salmocins for control of Salmonella pathovars

Abstract

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.

Techno‐economic analysis of a plant‐based platform for manufacturing antimicrobial proteins for food safety

“…11,14,22 Several salmocins and lysins can be expressed at high levels in spinach, which is comparable to expression levels in N. benthamiana. The alternative scenario models were designed in alignment with base case scenario inputs unless otherwise noted; each alternative scenario was chosen to isolate the impact of a key facility design assumption.…”

“…11,14,15,[22][23][24] In this study, we address cost sensitivity with a comprehensive techno-economic analysis of plant-based production of AMP for food safety applications. Plant-based platforms have the potential for producing market-relevant volumes of AMPs at competitive costs, because they do not require expensive bioreactors and culture media.…”

Engineering bacteriocin‐mediated resistance against the plant pathogen Pseudomonas syringae

“…We conclude that PL1 has a very specific killing spectrum making it an ideal candidate for expression in plants. Previously, bacteriocins that are active against human pathogens have been expressed in N. benthamiana leaves and in leafy green vegetables (Schulz et al, 2015;Pa skevi cius et al, 2017;Schneider et al, 2018). To express PL1 in planta, a construct that encodes PL1 with an N-terminal 4 9 c-Myc tag was cloned into a Ti binary vector and transiently expressed in leaves of N. benthamiana using agroinfiltration.…”

“…We are not aware of any prior reports of attempts to express bacteriocins in planta as a strategy to confer resistance against plant pathogenic bacteria. Bacteriocins with activities against E. coli , Salmonella and Pseudomonas aeruginosa have been expressed in plants but with the objective of using these as a means of treating bacterial infections in humans (Schulz et al , ; Paškevičius et al , ; Schneider et al , ). The resulting successful demonstration that active bacteriocins can be expressed in planta suggests that PL1 could also be expressed in planta in an active form to protect plants against Ps infection.…”

LlpB represents a second subclass of lectin‐like bacteriocins

“…Among Gram-negative bacteria, bacteriocins from Escherichia coli (colicins) and Pseudomonas aeruginosa (pyocins) serve as model systems for studying receptor binding, cell import mechanisms and toxin-immunity interactions (Cascales et al, 2007;Papadakos et al, 2012;Ghequire and De Mot, 2014;Chassaing and Cascales, 2018). These compounds are potent antibacterials and their use in food and therapeutic applications is currently being investigated (Schulz et al, 2015;Pa skevi cius et al, 2017;Scholl, 2017;Schneider et al, 2018). Major advantages of bacteriocins include biodegradability, selective killing and eligibility (of some bacteriocins) for large-scale production in plants (Behrens et al, 2017;Ghequire and De Mot, 2018).…”