Isolation and Characterization of Lytic Pseudomonas fluorescens Bacteriophage isolated from milk

Abstract

Phage-based biocontrol is an alternative method for preventing and controlling the occurrence of Pseudomonas spp. in food products. However the use of bacteriophages to control heat-stable protease Pseudomonas fluorescens is still rare. The objectives of this study were to isolate lytic bacteriophages of P. fluorescens and to evaluate their efficacy in controlling P. fluorescens at the laboratory level. Among these strains only one phage ?TIS1 was isolated by using P. fluorescens TISTR 1887 as the host. Further analysis using electron microscopy indicated that ?TIS1 belongs to the Myoviridae family. This phage ?TIS1 was relatively stable at pH and temperature ranges of 4.0 to 12.0 and 4 30 37 and 45?C respectively after 1.5 h incubation. The partial ?TIS1 genome was a linear double-stranded with a total length of 87 646 bp and a G + C content of 54.71%. In vitro studies of the effect of bacteriophages against P. fluorescens TISTR 1887 with phage ?TIS1 using various multiplicity of infection (MOI) values showed a significant decrease in bacterial numbers during 6-12 hours of incubation followed by bacterial regrowth. However the phage was still able to significantly reduce the bacterial numbers compared to the control without phage. These findings suggest that phage ?TIS1 has the potential to be an effective method for controlling the prevalence of spoilage-causing P. fluorescens strains in dairy industries. ? 2018-2023 Rangsit University.