Characterization and In Vitro Efficacy against Listeria monocytogenes of a Newly Isolated Bacteriophage, ΦIZSAM-1

Abstract

Listeria monocytogenes is a bacterial pathogen responsible of listeriosis, a disease that in humans is often related to the contamination of ready-to-eat foods. Phages are candidate biodecontaminants of pathogenic bacteria thanks to their ability to lyse prokaryotes while being safe for eukaryotic cells. In this study, ɸIZSAM-1 was isolated from the drain-waters of an Italian blue cheese plant and showed lytic activity against antimicrobial resistant Listeria monocytogenes strains. This phage was subjected to purification and in vitro efficacy tests. The results showed that at multiplicities of infection (MOIs) ≤ 1, phages were able to keep Listeria monocytogenes at low optical density values up to 8 h, with bacterial counts ranging from 1.02 to 3.96 log10 units lower than the control. Besides, ɸIZSAM-1 was further characterized, showing 25 principal proteins (sodium dodecyl sulfate polyacrylamide gel electrophoresis profile) and a genome of approximately 50 kilo base pairs. Moreover, this study describes a new approach to phage isolation for applications in Listeriamonocytogenes biocontrol in food production. In particular, the authors believe that the selection of phages from the same environments where pathogens live could represent a new approach to successfully integrating the control measures in an innovative, cost effective, safe and environmentally friendly way.

Phages and Enzybiotics in Food Biopreservation

“…The isolation of phages from sewage and water samples is common due to their abundance in these ecosystems. However, Scattolini et al, pointed out that the search and characterization of phages isolated in the same foods in which the pathogens can hide could be a good way “to integrate this control measure in an innovative, cost-effective, safe and environmentally friendly way” [ 86 ]. Therefore, it seems like a good idea to use phages in food safety which in turn come from food, especially for the consumer, who can identify fewer drawbacks than when consuming phages or their genetically manipulated enzybiotics.…”

Application of Bacteriophages for Human Health: An Old Approach against Contemporary “Bad Bugs”

“…At the same time, this collection reports many descriptions of newly characterized phages, which could be good candidates for the treatment of human infections due to Enterococcus faecalis [ 8 , 9 ], Klebsiella pneumoniae [ 10 ], Escherichia coli [ 11 ] and Pseudomonas aeruginosa [ 12 ] or to combat phytopathogens [ 13 , 14 ] or bacteria responsible for foodborne diseases [ 15 , 16 , 17 ]. It is relevant to underscore that, besides the use of standard techniques for general characterization of phages, some contributions evaluated their effective activity on bacterial biofilm [ 8 , 11 , 12 ] or on animal infection models [ 9 , 10 ], while others took original experimental approaches tailored to the future intended usage of the investigated phages [ 8 , 13 , 16 ].…”