title: Co-loaded proteinase K/thyme oil liposomes for inactivation of Escherichia coli O157:H7 biofilms on cucumber.
abstract: E. coli O157:H7 is a bacterium frequently found on vegetable surfaces, such as cucumber, that can pose a significant threat to consumers. In the present work, proteinase K (PK) and thyme oil (TO) were used to inactivate E. coli O157:H7 biofilms. Both PK and TO were encapsulated in liposomes to improve their chemical stability and to allow for a controlled release. The optimal PK/TO-loaded liposomes (particle size of 170.4 nm, polydispersity index of 0.309, zeta potential of -29.8 mV and entrapment efficiency of 33.2%) were engineered. The antibacterial activities of the PK/TO liposomes against E. coli O157:H7 biofilms in vitro and on the cucumber were observed. Compared to free PK, free TO, and free PK/TO and TO liposome treatments, PK/TO-liposomes exhibited a higher antibiofilm activity and longer action duration. Specifically, the counts of viable E. coli O157:H7 on cucumbers were reduced by 1.23, 2.32 and 2.44 Logs after treatment with 400 mg mL-1of PK/TO liposomes for 3 d, at 5, 15 and 25 °C, respectively. Colorimetric analysis and sensory tests showed that the PK/TO-liposome treatment had almost no impact on food quality after 1 d.
authors.affiliation: School of Food & Biological Engineering, Jiangsu University, Zhenjiang 212013, P.R. China. linl@ujs.edu.cn.
authors.forename: Haiying
authors.initials: H
authors.lastname: Cui
authors.affiliation: School of Food & Biological Engineering, Jiangsu University, Zhenjiang 212013, P.R. China. linl@ujs.edu.cn.
authors.forename: Cuixia
authors.initials: C
authors.lastname: Ma
authors.affiliation: School of Food & Biological Engineering, Jiangsu University, Zhenjiang 212013, P.R. China. linl@ujs.edu.cn.
authors.forename: Lin
authors.identifier: http://orcid.org/0000-0001-6374-2165
authors.initials: L
authors.lastname: Lin
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D002681:China; D003080:Cold Temperature; D018553:Cucumis sativus / Q000737:chemistry / Q000382:microbiology*; D019286:Endopeptidase K / Q000737:chemistry / Q000378:metabolism*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D019453:Escherichia coli O157 / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D005518:Food Preferences; D005520:Food Preservatives / Q000737:chemistry / Q000378:metabolism; D063427:Food Quality; D061353:Food Storage; D005638:Fruit / Q000737:chemistry / Q000382:microbiology*; D006801:Humans; D007700:Kinetics; D008081:Liposomes; D050296:Microbial Viability; D009822:Oils, Volatile / Q000737:chemistry / Q000378:metabolism*; D010316:Particle Size; D010860:Pigments, Biological / Q000032:analysis / Q000737:chemistry; D013499:Surface Properties; D046930:Thymus Plant / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D005520:Food Preservatives; D008081:Liposomes; D009822:Oils, Volatile; D010860:Pigments, Biological; D019286:Endopeptidase K