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THE EFFECTS OF LIQUID HOLDING ON NEAR‐UV(300–400 nm) IRRADIATED ESCHERICHIA COLI STRAINS DIFFERING IN NEAR AND FAR‐UV RADIATION SENSITIVITY
Author(s) -
Tuveson R. W.,
Violante Edward V.
Publication year - 1982
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/j.1751-1097.1982.tb02656.x
Subject(s) - escherichia coli , irradiation , lysis , radiation , bacteria , stationary phase , leakage (economics) , chemistry , biophysics , biology , chromatography , biochemistry , optics , physics , genetics , nuclear physics , gene , macroeconomics , economics
— Stationary phase cells from four Escherichia coli strains differing in near‐ (nur vs. nur + ) and far‐UV (recAl vs. recA + ) radiation sensitivity were subjected to near‐UV radiation (NUV) in 0.85% saline. Although the NUV‐irradiated cultures yielded increased colony numbers following 24 h of liquid holding (LH), a fluctuation test for each experiment showed that the observed increases were not due to recovery but were in fact due to cell multiplication. The decline in viability observed after NUV with liquid holding using the fluctuation test was equivalent in strains RT2, 3 and 4 while the decline observed with RT1 was less marked. The discrepancy between LH involving cell densities of 10 8 ‐10 9 and 1–4 cells/m/ can be resolved by assuming that with dense cell suspensions, NUV‐induced membrane damage leads to leakage or lysis, supplying sufficient nutrients to allow growth of undamaged, surviving cells.