Bacterial viruses known as bacteriophages have been demonstrated to be effective in killing foodborne pathogens such as Shigella flexneri. Adsorption is the first step in the phage-host interaction. In the present work, 10 Shigella phages were used to characterize the adsorption process on Shigella flexneri ATCC12022 in several physicochemical conditions related to food and in a food matrix. One-step growth curves were drawn for all the Shigella-phages evaluated. Furthermore, the adsorption rate for each of the 10 phages was determined. In addition, the influence of temperature, Na+, Mg2+, pH, sucrose and glycerol on phage adsorption was investigated. Two phages (Shi22 and Shi30) showed higher burst sizes values (67 and 64 PFU cell-1, respectively) and burst times of 25 min to 30 min, while the other eight phages exhibited burst sizes ranging from 14 to 17 PFU cell-1 with slower burst times. Furthermore, most phages achieved a high adsorption rate, and the adsorption constants (k) ranged from ~10-9 to 10-10 mL min-1. Regarding the influence of temperature, cations and pH, a high or moderate percentage of adsorption was observed for most of the phages evaluated. The adsorption decreased at increasing concentrations of Na+, sucrose and glycerol, although at different levels, since adsorption was more affected by sucrose than by glycerol and Na+ for most phages. The adsorption obtained in Triptein soy broth (TSB) for most of the phages/strain systems evaluated was moderate or high, as well as those observed in a food matrix. Thus, our phages could potentially be used to improve food safety under a wide range of environmental conditions against foodborne pathogens.
Keywords: Shigella flexneri; adsorption; bacteriophage; food safety.