Application of Lytic Bacteriophages and Their Enzymes to Reduce Saprophytic Bacteria Isolated from Minimally Processed Plant-Based Food Products—In Vitro Studies

Abstract

The aim of this study was to isolate phage enzymes and apply them in vitro for eradication of the dominant saprophytic bacteria isolated from minimally processed food. Four bacteriophages—two Enterobacter-specific and two Serratia-specific, which produce lytic enzymes—were used in this research. Two methods of phage enzyme isolation were tested, namely precipitation with acetone and ultracentrifugation. It was found that the number of virions could be increased almost 100 times due to the extension of the cultivation time (72 h). The amplification of phage particles and lytic proteins was dependent on the time of cultivation. Considering the influence of isolated enzymes on the growth kinetics of bacterial hosts, proteins isolated with acetone after 72-hour phage propagation exhibited the highest inhibitory effect. The reduction of bacteria count was dependent on the concentration of enzymes in the lysates. The obtained results indicate that phages and their lytic enzymes could be used in further research aiming at the improvement of microbiological quality and safety of minimally processed food products.

Biological Characterization and Genomic Analysis of Three Novel Serratia- and Enterobacter-Specific Virulent Phages

“…EPS depolymerases are believed to be effective in dispersing biofilms [ 40 ]. Photos of phage plaques on bacterial lawn, the procedure for isolating bacteriophage enzymes, and assessing their impact on limiting bacterial growth were described in an earlier article by Shymialevich et al [ 41 ]. The morphology of the isolated bacteriophages was visualized by TEM, and the electron micrographs are shown in Figure 1 .…”

Effectiveness of a Phage Cocktail as a Potential Biocontrol Agent against Saprophytic Bacteria in Ready-To-Eat Plant-Based Food

“…Four of the phages studied (i.e., Enterobacter phage KKP 3262 against Enterobacter cloacae strain KKP 3082, Enterobacter phage KKP 3263 against Enterobacter ludwigii strain KKP 3083, Serratia phage KKP 3264 against Serratia fonticola strain KKP 3084, and Citrobacter phage KKP 3664 against Citrobacter freundii strain KKP 3655) were comprehensively characterized in our previous study [ 20 ], and genome sequences have been deposited in the GenBank database under the accession numbers OK210076, OK210074, OK210077, and OK210075, respectively. In addition, another three enzyme-producing phages (i.e., Serratia phage KKP 3708 against Serratia liquefaciens strain KKP 3654, Serratia phage KKP 3709 against Serratia marcescens strain KKP 3687, and Enterobacter phage KKP 3711 against Enterobacter cloacae strain KKP 3684) were described by Shymialevich et al [ 71 ].…”