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Mathematical Modeling for Evaluating Inherent Parameters Affecting UVC Decontamination of Indicator Bacteria
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Document Title
Mathematical Modeling for Evaluating Inherent Parameters Affecting UVC Decontamination of Indicator Bacteria
Author
Jaiaue P, Piluk J, Sawattrakool K, Thammakes J, Malasuk C, Thitiprasert S, Thongchul N, Siwamogsatham S
Name from Authors Collection
Affiliations
Chulalongkorn University; Chulalongkorn University; Chulalongkorn University; National Science & Technology Development Agency - Thailand
Type
Article
Source Title
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
ISSN
0099-2240
Year
2022
Volume
88
Issue
1
Open Access
Green Published
Publisher
AMER SOC MICROBIOLOGY
DOI
10.1128/aem.02148-21
Format
Abstract
UV light is a tool associated with the denaturation of cellular components, DNA damage, and cell disruption. UV treatment is widely used in the decontamination process; however, predicting a sufficient UV dose by using traditional methods is doubtful. In this study, an in-house UVC apparatus was designed to investigate the process of the inactivation of five indicator bacteria when the initial cell concentrations and irradiation intensities varied. Both linear and nonlinear mathematical models were applied to predict the inactivation kinetics. In comparison with the Weibull and modified Chick-Watson models, the Chick-Watson model provided a good fit of the experimental data for five bacteria, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus faecalis, and Bacillus subtilis. The specific death rate (k(d)) significantly increased when the irradiation intensity (I) increased from 1.41 W/m(2) to 3.02 W/m(2) and 4.83 W/m(2) (P < 0.05). Statistical analysis revealed no significant difference in the k(d) values among the groups of tested Gram-positive bacteria, Gram-negative bacteria, and B. subtilis spores, but the k(d) values differed among groups (P < 0.05). The death rate coefficient (k) varied from species to species. The k values of the tested Gram-positive bacteria were higher than those of the Gram-negative bacteria. The thick peptidoglycan layer in the Gram-positive membrane was responsible for UVC resistance. The high guanine-cytosine (GC) content in bacteria also contributed to UV resistance due to the less photoreactive sites on the nucleotides. This investigation provides a good understanding of bacterial inactivation induced by UVC treatment. IMPORTANCE Prevention and control measures for microbial pathogens have attracted worldwide attention due to the recent coronavirus disease 2019 pandemic. UV treatments are used as a commercial control to prevent microbial contamination in diverse applications. Microorganisms exhibit different UV sensitivities, which are often measured by the UV doses required for decreasing the number of microbial contaminants in the logarithmic order. The maximum efficacy of UV is usually observed at 254 nm (residing in the UVC range of the light spectrum). UV technology is a nonthermal physical decontamination measure that does not require any chemicals and consumes low levels of energy while leaving insignificant amounts of chemical residues or toxic compounds. Therefore, obtaining the microbial death kinetics and their intrinsic parameters provided in this study together with the UV photoreaction rate enables advancement in the design of UV treatment systems. Prevention and control measures for microbial pathogens have attracted worldwide attention due to the recent coronavirus disease 2019 pandemic. UV treatments are used as a commercial control to prevent microbial contamination in diverse applications.
Funding Sponsor
National Security and Dual-Use Technology Center, National Science and Technology Development Agency (NSTDA); National Research Council of Thailand; National Science and Technology Development Agency (NSTDA); Thailand Research Fund [RTA6280014]
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Publication Source
WOS