Viability loss and morphology change of foodborne pathogens following exposure to hydrostatic pressures in the presence and absence of bacteriocins

Cell suspensions of three pathogens were exposed to hydrostatic pressure (HP), bacteriocin mixture (nisin and pediocin) or a combination of HP+bacteriocins and changes in colony forming units (cfu) and cell-morphology by scanning electron microscopy (SEM) were studied. Cell viability loss, as determined from the reduction in cfu before and after a treatment, occurred in Listeria monocytogenes by all three treatments and in Salmonella typhimurium and Escherichia coli O157:H7 by HP and HP+ bacteriocin combination. Cell wall and cell membrane collapse and cell lysis was indicated in L. monocytogenes exposed to bacteriocin or HP+ bacteriocin and in Salmonella and E. coli exposed to HP or HP+ bacteriocin. (C) 2003 Elsevier B.V. All rights reserved.