Detergent effects on disinfectant susceptibility of Escherichia coli and listeria monocytogenes attached to stainless steel

2.50
Hdl Handle:
http://hdl.handle.net/2436/279612
Title:
Detergent effects on disinfectant susceptibility of Escherichia coli and listeria monocytogenes attached to stainless steel
Authors:
Walton, Julie
Abstract:
This study investigated the effect of detergent treatment on susceptibility of attached Escherichia coli and Listeria monocytogenes to subsequent disinfectant treatment, in relation to food industry cleaning procedures. E. coli attached to stainless steel surfaces became significantly more susceptible to benzalkonium chloride (BAC) after treatment with sodium alkyl sulphate (SAS) by 0.51 Log10 cfu ml-1 and fatty alcohol ethoxylate (FAE) by 0.96 Log10 cfu ml-1. No change in susceptibility was observed with sodium dodecyl sulphate (SDS), sodium lauryl ethyl sulphate (SLES) or polyethoxylated alcohol (PEA). L. monocytogenes became significantly less susceptible to BAC after treatment with anionic detergents SAS by 0.79 Log10 cfu ml-1, SDS by 0.33 Log10 cfu ml-1 and SLES by 0.22 Log10 cfu ml-1, yet no change in susceptibility was observed with FAE. Following treatment with all detergents both organisms became significantly more susceptible to sodium dichloroisocyanurate (NaDCC) demonstrating that the effect of the disinfectant was independent of detergent type. Flow cytometry using the fluorochrome propidium iodide (PI) revealed significant increases in cell membrane permeability of both organisms by all detergents except sodium dodecyl sulphate (SDS) and the effect was much greater in E. coli. Increasing above the in-use concentration of SAS and FAE had no further effect on cell membrane permeability, or susceptibility to BAC. Hydrophobic interaction chromatography (HIC) showed that E. coli became less hydrophobic following treatment with SAS, SDS, FAE and L. monocytogenes became less hydrophobic following treatment with SAS and SDS but no effect was seen with FAE. Investigations into carbon chain length of detergent revealed that SAS and the C18 standard increased susceptibility of E. coli to BAC which, with permeability results, suggests a link between increase in susceptibility to BAC and increase in membrane permeability. Efflux experiments with L. monocytogenes showed that efflux of ethidium bromide (EtBr) was greater from cells treated with SAS than with FAE suggesting that the anionic charge on the detergent molecule influences an efflux mechanism that reduces susceptibility to BAC. Overall the results demonstrate that detergent type can influence the sensitivity of persistent food borne microorganisms to BAC and NaDCC and the significance of the findings may impact on the choice of agents used in cleaning procedures in the food industry.
Advisors:
Gibson, Hazel
Publisher:
University of Wolverhampton
Issue Date:
Jul-2012
URI:
http://hdl.handle.net/2436/279612
Type:
Thesis or dissertation
Language:
en
Description:
A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophy
Appears in Collections:
E-Theses

Full metadata record

DC FieldValue Language
dc.contributor.advisorGibson, Hazelen_GB
dc.contributor.authorWalton, Julieen_GB
dc.date.accessioned2013-04-10T12:41:51Z-
dc.date.available2013-04-10T12:41:51Z-
dc.date.issued2012-07-
dc.identifier.urihttp://hdl.handle.net/2436/279612-
dc.descriptionA thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophyen_GB
dc.description.abstractThis study investigated the effect of detergent treatment on susceptibility of attached Escherichia coli and Listeria monocytogenes to subsequent disinfectant treatment, in relation to food industry cleaning procedures. E. coli attached to stainless steel surfaces became significantly more susceptible to benzalkonium chloride (BAC) after treatment with sodium alkyl sulphate (SAS) by 0.51 Log10 cfu ml-1 and fatty alcohol ethoxylate (FAE) by 0.96 Log10 cfu ml-1. No change in susceptibility was observed with sodium dodecyl sulphate (SDS), sodium lauryl ethyl sulphate (SLES) or polyethoxylated alcohol (PEA). L. monocytogenes became significantly less susceptible to BAC after treatment with anionic detergents SAS by 0.79 Log10 cfu ml-1, SDS by 0.33 Log10 cfu ml-1 and SLES by 0.22 Log10 cfu ml-1, yet no change in susceptibility was observed with FAE. Following treatment with all detergents both organisms became significantly more susceptible to sodium dichloroisocyanurate (NaDCC) demonstrating that the effect of the disinfectant was independent of detergent type. Flow cytometry using the fluorochrome propidium iodide (PI) revealed significant increases in cell membrane permeability of both organisms by all detergents except sodium dodecyl sulphate (SDS) and the effect was much greater in E. coli. Increasing above the in-use concentration of SAS and FAE had no further effect on cell membrane permeability, or susceptibility to BAC. Hydrophobic interaction chromatography (HIC) showed that E. coli became less hydrophobic following treatment with SAS, SDS, FAE and L. monocytogenes became less hydrophobic following treatment with SAS and SDS but no effect was seen with FAE. Investigations into carbon chain length of detergent revealed that SAS and the C18 standard increased susceptibility of E. coli to BAC which, with permeability results, suggests a link between increase in susceptibility to BAC and increase in membrane permeability. Efflux experiments with L. monocytogenes showed that efflux of ethidium bromide (EtBr) was greater from cells treated with SAS than with FAE suggesting that the anionic charge on the detergent molecule influences an efflux mechanism that reduces susceptibility to BAC. Overall the results demonstrate that detergent type can influence the sensitivity of persistent food borne microorganisms to BAC and NaDCC and the significance of the findings may impact on the choice of agents used in cleaning procedures in the food industry.en_GB
dc.language.isoenen
dc.publisherUniversity of Wolverhamptonen
dc.subjectdetergenten_GB
dc.subjectbenzalkonium chlorideen_GB
dc.subjectflow cytometryen_GB
dc.subjectcell surface hydrophobicityen_GB
dc.subjectsusceptibilityen_GB
dc.subjecteffluxen_GB
dc.titleDetergent effects on disinfectant susceptibility of Escherichia coli and listeria monocytogenes attached to stainless steelen_GB
dc.typeThesis or dissertationen
dc.type.qualificationnamePhDen
dc.type.qualificationlevelMasters Degreeen
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