APPLICATION OF BACTERIOPHAGE AS BIO-SENSOR FOR DETECTION OF SOME FOOD-BORNE PATHOGENIC BACTERIA

Abstract

Food-borne diseases are a gastrointestinal infection caused by foods containing harmful bacteria that caused by fecal contamination. Salmonella spp. are a most common cause of food-borne bacterial infections. This study aimed to detect Salmonella spp. in food product by phages. From 41 environmental and plant samples 22 bacterial isolates showed typical colonies on specific media XLD and Bismuth Sulphite agar. Tenisolates were confirmed as S. enterica using16S rRNA gene sequencing. Three highly lytic phages were detected against these strains. These phages named as Ø sal-1, Øsal-2 and Ø sal-3 Salmonella phages. They were isolated from the same samples collected to isolate Salmonella spp. Transmission electron microscopy revealed that, one of these phages (Øsal-1) has contractile tail and therefore belongs to the family Myoviridae, while the other two isolates (Ø sal-2 and Ø sal-3) had non-contractile tails, and therefore belong to the family Siphoviridae, these phages could infect S. enterica subsp. Enterica serotype. Typhimuriumbut couldn’t infect E.coli,Enterococcus and Enterobacter isolates .Phages were stable under different physical and chemical conditions. They endured high temperatures up to 72°C and pH ranged from 5 - 11, while they retained activity in NaCl solutions up to 3%. The phage Ø sal-3 was particularly interesting because it had higher rate and capacity of adsorption than the other two phages. Burst sizes were 124,121and 133 PFU and latent periods ranged from 45-50min observed for all isolate phages for phages Ø sal-1, Ø sal-2 and Ø sal-3 respectively.