Inactivation of Listeria monocytogenes/Flavobacterium spp. biofilms using chlorine: impact of substrate, pH, time and concentration.
OBJECTIVE
To determine the effect of chlorine on mixed bacterial biofilms on stainless steel (SS) and conveyor belt surfaces.


RESULTS
Biofilms were exposed to pH-adjusted (6.5) and non-pH-adjusted solutions of chlorine (200, 400 and 600 ppm) for either 2, 10 or 20 min and survivors enumerated. There were significant differences in cell death relating to chlorine concentration and exposure time for the cells attached to the SS, with solutions adjusted to pH 6.5 being more effective at reducing numbers. In contrast, on conveyor belt surfaces cell numbers decreased by less than two logs after 20 min regardless of treatment.


CONCLUSIONS
Chlorine effectiveness is dependent on its concentration, solution pH, exposure time, the nature of the surface and the microbial species present. SIGNIFICANCE AND IMPACT OF THE STUDY the interests of food safety it is important that sanitizer users are aware of the conditions that effect their performance.
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002713:Chlorine / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods; D005417:Flavobacterium / Q000187:drug effects* / Q000502:physiology; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D011143:Polyvinyl Chloride; D012996:Solutions; D013193:Stainless Steel; D013997:Time Factors
D000900:Anti-Bacterial Agents; D012996:Solutions; D013193:Stainless Steel; D002713:Chlorine; D011143:Polyvinyl Chloride