title: Inactivation and changes in metabolic profile of selected foodborne bacteria by 460 nm LED illumination.
abstract: The objective of this study was to investigate the effect of 460 nm light-emitting diode (LED) on the inactivation of foodborne bacteria. Additionally, the change in the endogenous metabolic profile of LED illuminated cells was analyzed to understand the bacterial response to the LED illumination. Six different species of bacteria (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, Pseudomonas aeruginosa and Salmonella Typhimurium) were illuminated with 460 nm LED to a maximum dose of 4080 J/cm2at 4, 10 and 25 °C. Inactivation curves were modeled using Hom model. Metabolic profiling of the non-illuminated and illuminated cells was performed using a Liquid chromatography-mass spectrometry system. Results indicate that the 460 nm LED significantly (p < 0.05) reduced the populations of all six bacterial species. For example, the population of S. aureus reached below detection limit within 7 h. B. cereus was most resistant to photo-inactivation and exhibited about 3-log reduction in 9 h. Metabolic profiling of the illuminated cells indicated that several metabolites e.g. 11-deoxycortisol, actinonin, coformycin, tyramine, chitobiose etc. were regulated during LED illumination. These results elucidate the effectiveness of 460 nm LED against foodborne bacteria and hence, its suitability as a novel antimicrobial control method to ensure food safety.
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Vinayak
authors.initials: V
authors.lastname: Ghate
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Min-Jeong
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore; National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, Suzhou, Jiangsu, 215123, China.
authors.forename: Weibiao
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Post-Harvest Technology Department, Technology & Industry Development Group, Agri-Food & Veterinary Authority of Singapore, 2 Perahu Road, 718915, Singapore.
authors.forename: Gek Hoon
authors.initials: GH
authors.lastname: Khoo
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore; National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, Suzhou, Jiangsu, 215123, China. Electronic address: chmyukhg@nus.edu.sg.
authors.forename: Hyun-Gyun
authors.initials: HG
authors.lastname: Yuk
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000528:radiation effects*; D002853:Chromatography, Liquid; D003070:Coformycin / Q000378:metabolism; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000254:growth & development / Q000528:radiation effects; D005516:Food Microbiology / Q000379:methods; D005519:Food Preservation / Q000379:methods; D059022:Food Safety / Q000379:methods*; D006877:Hydroxamic Acids / Q000378:metabolism; D008027:Light; D057230:Limit of Detection; D008089:Listeria monocytogenes / Q000254:growth & development / Q000528:radiation effects; D055442:Metabolome / Q000528:radiation effects; D050296:Microbial Viability / Q000528:radiation effects*; D018384:Oxidative Stress; D013696:Temperature
chemical_list: D006877:Hydroxamic Acids; D003070:Coformycin; C010531:actinonin
keywords: Endogenous metabolites; Foodborne bacteria; Light emitting diode; Oxidative stress; Photo-inactivation