title: Effects of environmental parameters on the dual-species biofilms formed by Escherichia coli O157:H7 and Ralstonia insidiosa, a strong biofilm producer isolated from a fresh-cut produce processing plant.
abstract: Biofilm-forming bacteria resident to food processing facilities are a food safety concern due to the potential of biofilms to harbor foodborne bacterial pathogens. When cultured together, Ralstonia insidiosa, a strong biofilm former frequently isolated from produce processing environments, has been shown to promote the incorporation of Escherichia coli O157:H7 into dual-species biofilms. In this study, interactions between E. coli O157:H7 and R. insidiosa were examined under different incubating conditions. Under static culture conditions, the incorporation of E. coli O157:H7 into biofilms with R. insidiosa was not significantly affected by either low incubating temperature (10°C) or by limited nutrient availability. Greater enhancement of E. coli O157:H7 incorporation in dual-species biofilms was observed by using a continuous culture system with limited nutrient availability. Under the continuous culture conditions used in this study, E coli O157:H7 cells showed a strong tendency of colocalizing with R. insidiosa on a glass surface at the early stage of biofilm formation. As the biofilms matured, E coli O157:H7 cells were mostly found at the bottom layer of the dual-species biofilms, suggesting an effective protection by R. insidiosa in the mature biofilms.
authors.affiliation: Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA; Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20740, USA.
authors.forename: Nancy T
authors.initials: NT
authors.lastname: Liu
authors.affiliation: Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA. xiangwu.nou@ars.usda.gov.
authors.forename: Xiangwu
authors.initials: X
authors.lastname: Nou
authors.affiliation: Electron and Confocal Microscopy Unit, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA.
authors.forename: Gary R
authors.initials: GR
authors.lastname: Bauchan
authors.affiliation: Electron and Confocal Microscopy Unit, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Murphy
authors.affiliation: Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Lefcourt
authors.affiliation: Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Shelton
authors.affiliation: Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20740, USA.
authors.forename: Y Martin
authors.initials: YM
authors.lastname: Lo
mesh_terms: D058491:Bacterial Load; D018441:Biofilms / Q000254:growth & development*; D004777:Environment; D019453:Escherichia coli O157 / Q000502:physiology*; D005511:Food Handling; D005516:Food Microbiology; D043367:Ralstonia / Q000502:physiology*; D013696:Temperature