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PHOTOKILLING OF MICROCOCCUS ROSEUS
Author(s) -
Dieringer S. M.,
Singer J. T.,
Cooney J. J.
Publication year - 1977
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.1751-1097.1977.tb07503.x
Subject(s) - photosensitizer , carotenoid , micrococcus , photodynamic therapy , chemistry , endogeny , biochemistry , mutant , light intensity , bacteria , biophysics , biology , photochemistry , optics , physics , organic chemistry , gene , genetics
Abstract. Previous work showed that the bacterium Micrococcus roseus is killed by photodynamic action when an exogenous photosensitizer is present, but when a photosensitizer is not added the organism survives long exposure to high intensity (22,000ft‐c, 348 J/s/m 2 ) white light. Experiments designed to demonstrate the presence of a mechanism to repair damage caused by photodynamic action failed to reveal such a mechanism. However, the organism was killed by light of a very high intensity (32,000ft‐c, 506 J/s/m 2 ) in the absence of added photosensitizer, indicating that cells have an effective endogenous photosensitizer(s). Two carotenoid‐deficient mutants were killed via photodynamic action more rapidly than the fully pigmented wild‐type in the presence or absence of an exogenous photosensitizer. Thus, resistance of M. roseus to photodynamic action is not due to a repair mechanism, nor to lack of an effective endogenous photosensitizer, but to the protective action of carotenoid pigments.