chapter 8.2 case study, Characteristics of bacteriophage isolates and expression of Shiga toxin genes transferred to non Shiga toxin producing E.coli by transduction

aim

not all strains of E. coli can produce shiga toxin, but there is a concern that environmental bacteriophages are helping to transfer this toxin gene to non-toxin producing E. coli

Hypothesis

strains of phage carrying Shiga toxin that were most effective at infecting E. coli  would also result in the highest rate of gene transfer. If they are better at infecting, they are better at gene transfer

background

Shiga toxin:

• produced by pathogenic E. coli  and Shigella dysenteriae

conclusion

• bacteriophages can mediate the transfer of Shiga toxin through transduction. This is because Shiga toxin 1 (stx1) is transferred more so than stx2

• More bacterial cell death is observed under high osmotic pressure (higher salt concentration)

• Shiga toxin is more highly expressed under high osmotic pressure. This increased expression in high salt could correlate to gut conditions