Four novel bacteriophages from slaughterhouse: Their potency on control of biofilm-forming MDR S. aureus in beef model

This study was designed to isolate and characterize novel lytic phages specific to Staphylococcus aureus (S. aureus) from wastewater samples, determine their antimicrobial and antibiofilm activities, and investigate the biocontrol efficiency of phages on raw beef contaminated with S. aureus. For this purpose, a total of 50 wastewaters from slaughterhouses were used as material, and phages were isolated with the double-layer agar method. The isolated and purified phages were characterized by whole genome sequence (WGS). Antibiofilm activity of individual phages and their cocktails (B2-102, T2-102, O1-102, and O1-69) was assessed by microplate titer plate. Five novel bacteriophages isolated with broad lytic activity against many S. aureus and E. coli strains. Four phages (B2-102, O1-102, T2-102, and O2-92) isolated belonged to the Herelleviridae family into the order Caudovirales while the remaining phage O1-69 belonged to the Siphoviridae family. No antibiotic resistance or virulence genes were determined in the isolated phages' genome. Results revealed that individual phages reduced the pre-formed mature biofilm structure by their host strains and S. epidermidis. The treatment of the individual phages and their cocktails on beef provided favorable results with a significant decrease in viable S. aureus count. Log reduction of viable S. aureus cell counts ranged from 2.00 to 3.3 CFU/g for individual phages, and from 3.1 to 4.2 cfu/g for cocktails. In conclusion, the characteristics of novel phages isolated provide strong evidence for making them a good candidate for reducing and controlling S. aureus in the food industry.