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Role of Ozone in UV ‐C Disinfection, Demonstrated by Comparison between Wild‐Type and Mutant Conidia of Aspergillus niger
Author(s) -
Liu Jing,
Zhou Lin,
Chen JiHong,
Mao Wang,
Li WenJian,
Hu Wei,
Wang ShuYang,
Wang ChunMing
Publication year - 2014
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12217
Subject(s) - ozone , chemistry , irradiation , aspergillus niger , melanin , conidium , pigment , nuclear chemistry , food science , botany , biology , biochemistry , organic chemistry , physics , nuclear physics
This study aimed to investigate the tolerance of a melanized wild‐type strain of Aspergillus niger ( CON 1) and its light‐colored mutant ( MUT 1) to UV –C light and the concomitantly generated ozone. Treatments were segregated into four groups based on whether UV irradiation was used and the presence or absence of ozone: (− UV , −O 3 ), (− UV , +O 3 ), (+ UV , −O 3 ) and (+ UV , +O 3 ). The survival of CON 1 and MUT 1 conidia under + UV decreased as the exposure time increased, with CON 1 showing greater resistance to UV irradiation than MUT 1. Ozone induced CON 1 conidium inactivation only under conditions of UV radiation exposure. While, the inactivation effect of ozone on MUT 1 was always detectable regardless of the presence of UV irradiation. Furthermore, the CON 1 conidial suspension showed lower UV light transmission than MUT 1 when examined at the same concentration. Compared with the pigment in MUT 1, the melanin in CON 1 exhibited more potent radical‐scavenging activity and stronger UV absorbance. These results suggested that melanin protected A. niger against UV disinfection via UV screening and free radical scavenging. The process by which UV –C disinfection induces a continual decrease in conidial survival suggests that UV irradiation and ozone exert a synergistic fungicidal effect on A. niger prior to reaching a plateau.