Efficacy and mechanism of combined inactivation of fungal spores by peracetic acid pretreatment and UV combined
WANG Jing-yi, WU Ge-hui, WAN Qi-qi, HUANG Ting-lin, WEN Gang
Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Shaanxi Key Laboratory of Environmental Engineering, Xi' an University of Architecture and Technology, Xi' an 710055, China
摘要 The study investigated the effects and mechanisms of fungal spore inactivation by pre-exposure to peracetic acid (PFA) combined with ultraviolet (UV) light and subsequent PFA treatment. It was found that PFA, as an effective disinfectant, could produce strong oxidative effects under low-pressure UV activation, disrupting the cell wall structure of fungal spores and thereby achieving inactivation. The results indicated that PFA pretreatment could enhance the subsequent UV/PFA combined disinfection process. Under the same UV and PFA dosage conditions, after 12minutes of PFA pretreatment followed by UV inactivation, the inactivation rates of Aspergillus niger and Aspergillus flavus increased to 3.67-log and 2.51-log, respectively, which were 1.21 and 1.17 times the effect of direct UV/PFA treatment. Additionally, the study examined the influence of pretreatment time, PFA concentration, pH value, and humic acid concentration on the inactivation effect. Increasing the pretreatment time and PFA concentration significantly improved the inactivation efficiency, while alkaline conditions and high humic acid concentrations were detrimental to the inactivation effect. Flow cytometry analysis revealed that the PFA-UV/PFA combined treatment caused more severe damage to the cell membrane and significantly increased reactive oxygen species levels. The generation of more hydroxyl radicals and stronger synergistic effects were key factors in enhancing the inactivation effect. Furthermore, the PFA-UV/PFA treatment was more effective in inhibiting the regeneration ability of incompletely inactivated fungal spores compared to the UV/PFA treatment alone. Compared to the PAA-UV/PAA system, the PFA-UV/PFA combined inactivation system demonstrated higher potential and efficiency in inactivating fungal spores.
Abstract：The study investigated the effects and mechanisms of fungal spore inactivation by pre-exposure to peracetic acid (PFA) combined with ultraviolet (UV) light and subsequent PFA treatment. It was found that PFA, as an effective disinfectant, could produce strong oxidative effects under low-pressure UV activation, disrupting the cell wall structure of fungal spores and thereby achieving inactivation. The results indicated that PFA pretreatment could enhance the subsequent UV/PFA combined disinfection process. Under the same UV and PFA dosage conditions, after 12minutes of PFA pretreatment followed by UV inactivation, the inactivation rates of Aspergillus niger and Aspergillus flavus increased to 3.67-log and 2.51-log, respectively, which were 1.21 and 1.17 times the effect of direct UV/PFA treatment. Additionally, the study examined the influence of pretreatment time, PFA concentration, pH value, and humic acid concentration on the inactivation effect. Increasing the pretreatment time and PFA concentration significantly improved the inactivation efficiency, while alkaline conditions and high humic acid concentrations were detrimental to the inactivation effect. Flow cytometry analysis revealed that the PFA-UV/PFA combined treatment caused more severe damage to the cell membrane and significantly increased reactive oxygen species levels. The generation of more hydroxyl radicals and stronger synergistic effects were key factors in enhancing the inactivation effect. Furthermore, the PFA-UV/PFA treatment was more effective in inhibiting the regeneration ability of incompletely inactivated fungal spores compared to the UV/PFA treatment alone. Compared to the PAA-UV/PAA system, the PFA-UV/PFA combined inactivation system demonstrated higher potential and efficiency in inactivating fungal spores.
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