Isolation, characterization of Enterococcus phages and their application in control of E. faecalis in milk

Abstract

Aims: Isolation and characterization of Enterococcus phages and application of phage cocktail to control E. faecalis in milk.

Methods and results: For phage isolations, double layer agar method was used. Host range of the phages were determined by the spot test. Twelve phages with varying host ranges were isolated. Phages PEF1, PEF7b, and PEF9 with different host ranges and lytic activities were selected for phage cocktails. Compared to two-phages cocktails tested, the cocktail containing all the three phages displayed stronger antibacterial and biofilm removal activities. The cocktail treatment reduced viable E. faecalis in biofilm by 6 log within 6 h at both 30°C and 4°C. In milk, the cocktail gradually reduced the viable count of E. faecalis and the count reached below the lower limit of detection at 48 h at 4°C.

Conclusion: The strong bactericidal and biofilm removal activities of the phage cocktail suggest the potential of this cocktail as a natural biocontrol agent for combating E. faecalis in milk.

Keywords: Enterococcus phages; activity at low temperature; application to milk; biofilm removal; phage cocktail.