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Effect of Freezing on Photoreactivation of Escherichia coli and Enterococcus faecalis
Author(s) -
Williams A.,
Gao W.,
Leung K.T.
Publication year - 2012
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143012x13347678384648
Subject(s) - photolyase , enterococcus faecalis , strain (injury) , microbiology and biotechnology , escherichia coli , irradiation , ultraviolet , ultraviolet irradiation , ultraviolet light , biology , chemistry , food science , materials science , biochemistry , dna repair , photochemistry , dna , physics , optoelectronics , anatomy , gene , nuclear physics
The effect of freezing on photoreactivation of two strains of Escherichia coli (ATCC strain 25922 and O157:H7 strain 961019) and two strains of Enterococcus faecalis (strain ATCC 51299, vancomycin‐resistant and strain ATCC 29212, vancomycin‐sensitive) following ultraviolet irradiation were examined. The level of log photoreactivation of the freezing treated test organisms (frozen at −7, −15, or −30 °C then thawed at room temperature prior to ultraviolet irradiation) was compared with that of the samples that had not been frozen. Freezing had obvious impact on the response of the test organisms to visible light following ultraviolet irradiation. Significantly lower levels of photoreactivation were observed in the freezing treated cells. The effect of freezing on the ability of the test microbes to photoreactivate seems to be strain and species dependent. Overall, the experimental results suggest that less photoreactivation could be expected if freezing is used as a treatment method prior to ultraviolet disinfection.