Efficacy and mechanism of inactivation of fungal spores by ultraviolet combined with performic acid process
WANG Jing-yi, WU Ge-hui, Lin Wei, 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
Abstract：The inactivation efficiency and mechanism of ultraviolet / performic acid (UV/PFA) combined process against two typical pathogenic fungi (Aspergillus Niger and Aspergillus flavus) were investigated in this study. It was found that UV/PFA could inactivate 1.21-log of Aspergillus Niger spores and 2.08-log of Aspergillus flavus spores at 8min, and the inactivation efficiency of combined inactivation was higher than the sum of the inactivation efficiency of PFA and UV alone, showing a synergistic effect. The mechanism of combined inactivation was mainly that UV activated PFA to generate strong oxidizing hydroxyl radicals (·OH) to cause damage to cell membranes, increased the level of intracellular reactive oxygen species to increase cellular stress, and also facilitated the penetration of PFA into the cell interior, thus enhancing the inactivation efficiency. UV played a major role in the combined inactivation process, followed by ·OH, which contributed 87% and 11% to Aspergillus Niger inactivation and 71% and 27% to Aspergillus flavus inactivation, respectively. In addition, after UV/PFA inactivation, the regeneration time of fungi was delayed and the maximum potential of regeneration growth was inhibited.
[1] Oliveira B R, Crespo M T B, San Romão M V, et al. New insights concerning the occurrence of fungi in water sources and their potential pathogenicity[J]. Water research, 2013,47(16):6338-6347. [2] 吴戈辉,赵辉,万琪琪,等.紫外灭活水中3种致病性曲霉的效能及其光复活控制[J].中国环境科学, 2022,42(3):1173-1181. WU G H, ZHAO H, WAN Q Q, et al. Efficacy of ultraviolet inactivation of three pathogenic Aspergillus species in water and control of photoreactivation[J]. China Environmental Science, 2022, 42(3):1173-1181. [3] 文刚,朱红,黄廷林,等.氯灭活地下水源中3种优势真菌的效能与机制[J].环境科学, 2016,37(11):4228-4234. WEN G, ZHU H, HUANG T L, et al. Efficacy and mechanism of chlorine inactivation of three dominant fungi in groundwater sources[J]. Environmental Science, 2016,37(11):4228-4234. [4] Xia Y C, Wan Q Q, Xu X Q, et al. Solar disinfection of fungal spores in water:Kinetics, influencing factors, mechanisms and regrowth[J]. Chemical Engineering Journal, 2022,428:132065. [5] Zhang C, Brown P J B, Miles R J, et al. Inhibition of regrowth of planktonic and biofilm bacteria after peracetic acid disinfection[J]. Water research, 2019,149:640-649. [6] Flores M J, Lescano M R, Brandi R J, et al. A novel approach to explain the inactivation mechanism of Escherichia coli employing a commercially available peracetic acid[J]. Water Science and Technology, 2014,69(2):358-363. [7] Zuo J, Xu X Q, Wan Q Q, et al. Inactivation of fungal spores in water with peracetic acid:Efficiency and mechanism[J]. Chemical Engineering Journal, 2022,427:131753. [8] Xu X, Zuo J, Wan Q, et al. Effective inactivation of fungal spores by the combined UV/PAA:Synergistic effect and mechanisms[J]. Journal of Hazardous Materials, 2022,430:128515. [9] Lin W, Zuo J, Li K, et al. Pre-exposure of peracetic acid enhances its subsequent combination with ultraviolet for the inactivation of fungal spores:Efficiency, mechanisms, and implications[J]. Water Research, 2022,229:119404. [10] Wang J, Wan Y, Ding J, et al. Thermal activation of peracetic acid in aquatic solution:The mechanism and application to degrade sulfamethoxazole[J]. Environmental Science&Technology, 2020, 54(22):14635-14645. [11] Maffettone R, Manoli K, Santoro D, et al. Performic Acid Disinfection of Municipal Secondary Effluent Wastewater:Inactivation of Murine Norovirus, Fecal Coliforms, and Enterococci[J]. Environmental Science&Technology, 2020,54(19):12761-12770. [12] 蒋励铭,卞静,张晓晖,等.电化学活化过氧乙酸灭活水中大肠杆菌[J].中国环境科学, 43(8):3966-3973. Jiang Li M, Bian J, Zhang X H, et al. Inactivation of Escherichia coli in water by electrochemically activated peroxyacetic acid[J]. China Environmental Science, 43(8):3966-3973. [13] Gehr R, Chen D, Moreau M. Performic acid (PFA):tests on an advanced primary effluent show promising disinfection performance[J]. Water Science and Technology, 2009,59(1):89-96. [14] Wen G, Xu X Q, Zhu H, et al. Inactivation of four genera of dominant fungal spores in groundwater using UV and UV/PMS:Efficiency and mechanisms[J]. Chemical Engineering Journal, 2017,328:619-628. [15] Campo N, De Flora C, Maffettone R, et al. Inactivation kinetics of antibiotic resistant Escherichia coli in secondary wastewater effluents by peracetic and performic acids[J]. Water Research, 2020,169:115227. [16] Xiao J, Wang M, Pang Z, et al. Simultaneous spectrophotometric determination of peracetic acid and the coexistent hydrogen peroxide using potassium iodide as the indicator[J]. Analytical Methods, 2019,11(14):1930-1938. [17] Wan Q Q, Wen G, Cao R H, et al. Simultaneously enhance the inactivation and inhibit the photoreactivation of fungal spores by the combination of UV-LEDs and chlorine:Kinetics and mechanisms[J]. Water Research, 2020,184:116143. [18] Wen G, Xu X Q, Huang T L, et al. Inactivation of three genera of dominant fungal spores in groundwater using chlorine dioxide:Effectiveness, influencing factors, and mechanisms[J]. Water Research, 2017,125:132-140. [19] Wen G, Cao R H, Wan Q Q, et al. Development of fungal spore staining methods for flow cytometric quantification and their application in chlorine-based disinfection[J]. Chemosphere, 2020,243:125453. [20] Lin J, Zou J, Cai H, et al. Hydroxylamine enhanced Fe (II)-activated peracetic acid process for diclofenac degradation:Efficiency, mechanism and effects of various parameters[J]. Water Research, 2021,207:117796. [21] Chandra J, Kuhn D M, Mukherjee P K, et al. Biofilm Formation by the Fungal Pathogen Candida albicans?:Development, Architecture, and Drug Resistance[J]. Journal of Bacteriology, 2001,183(18):5385-5394. [22] Geeraerd A H, Valdramidis V P, Van Impe J F. GInaFiT, a freeware tool to assess non-log-linear microbial survivor curves[J]. International Journal of Food Microbiology, 2005,102(1):95-105. [23] Buxton G V, Greenstock C L, Helman W P, et al. Critical Review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (OH/O-in Aqueous Solution[J]. Journal of Physical and Chemical Reference Data, 1988,17(2):513-886. [24] Lee Y, Von Gunten U. Oxidative transformation of micropollutants during municipal wastewater treatment:Comparison of kinetic aspects of selective (chlorine, chlorine dioxide, ferrateVI, and ozone) and non-selective oxidants (hydroxyl radical)[J]. Water Research, 2010, 44(2):555-566. [25] Malvestiti J A, Cruz-Alcalde A, Lopez-Vinent N, et al. Catalytic ozonation by metal ions for municipal wastewater disinfection and simulataneous micropollutants removal[J]. Applied Catalysis B:Environmental, 2019,259:118104.
