title: Effectiveness of chitosan against mature biofilms formed by food related bacteria.
abstract: Chitosan has proven antimicrobial properties against planktonic cell growth. Little is known, however, about its effects on already established biofilms. Oriented for application in food industry disinfection, the effectiveness of both medium molecular weight (MMW) chitosan and its enzymatically hydrolyzed product was tested against mature biofilms of four pathogenic strains, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus and Salmonella enterica, and a food spoilage species, Pseudomonas fluorescens. Unexpectedly, log reductions were in some cases higher for biofilm than for planktonic cells. One hour exposure to MMW chitosan (1% w/v) caused a 6 log viable cell reduction on L. monocytogenes monospecies mature biofilms and reduced significantly (3-5 log reductions) the attached population of the other organisms tested, except S. aureus. Pronase-treated chitosan was more effective than MMW chitosan on all tested microorganisms, also with the exception of S. aureus, offering best results (8 log units) against the attached cells of B. cereus. These treatments open a new possibility to fight against mature biofilms in the food industry.
authors.affiliation: Department of Nutrition, Food Science and Technology, Faculty of Veterinary, University Complutense of Madrid, Spain; E-Mails: maria.mlobete@gmail.com (M.M.L.); chpuga@estumail.es (C.H.P.); serran@vet.ucm.es (C.S.).
authors.forename: Belen
authors.initials: B
authors.lastname: Orgaz
authors.forename: Maria M
authors.initials: MM
authors.lastname: Lobete
authors.forename: Carmen H
authors.initials: CH
authors.lastname: Puga
authors.forename: Carmen
authors.initials: C
authors.lastname: San Jose
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001409:Bacillus cereus / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D048271:Chitosan / Q000494:pharmacology*; D005516:Food Microbiology; D008089:Listeria monocytogenes / Q000187:drug effects; D019779:Salmonella enterica / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D048271:Chitosan