Action of light on Micrococcus roseus

Abstract

1974. Action of light on Micrococc~ts roseus. Can. J.Microbiol. 20: 1015-1021. Micrococc~ts roseus is killed by exposure to a continuous spectrum of white light (3000 ft-c (32 292 Im/m2)) in the presence of air and the dye, toluidine blue. Comparison of rates of photodynamic killing for log and stationary phase cells and for two pigmentation mutants indicated that photosensitivity could not be correlated with amount of carotenoid or with carotenoid-chromophore length. Moreover, cells grown in medium containing diphenylamine (DPA) did not contain significant quantities of colored carotenoids; they were not as sensitive to photodynamic killing as fully pigmented cclls. Photodynamic killing was accompanied by selective release of magnesium and calcium and by release of UV-absorbing material. In the absence of added photosensitizer, M. rosetts, the two mutants, or DPA-inhibited cells were not killed when exposed to white light at intensities as high as 22 000 ft-c (236 806 Im/m2) for a s long as 9 h, and cells did not release UV-absorbing material. Under these conditions M . roseus and the yellow mutant did not release as much magnesium or calcium as when subjected to photodynamic killing, but DPA-grown cells leaked sodium, magnesium, and calcium. These observations are consistent with several suggestions: (i) carotenoids do not serve as photochemical buffers in M. roserts; (ii) growth in medium containing DPA or mutations leading to altered pigmentation change membrane organization leading to altered photosensitivity; (iii) M. roseus has an efficient repair mechanism which renders it resistant to photodynamic killing unless an exogenous photosensitizer is present. SCHWARTZEL, E. H., et J. J. COONEY. 1974. Action of light on Micrococcus roseus. Can. J.Microbiol. 20: 1015-1021. Micrococcus roselts est tuC par I'exposition un spectre continu de lumiere blanche (3000 ft-c (32 292 Im/m2)) en presence de I'air et d'un colorant toluidine bleu. La comparaison des taux de mortalite photodynamique pour les cellules en phase logarithmique et en phase stationnaire et pour les deux mutants a la pigmentation indique que la photosensibilite ne peut pas &tre corrdee avec la quantitt de carotkno'ide ou avec la longueur du chromophore caroteno'ide. En plus, les cellules qui se sont developpees dans un milieu contenant la diphenylamine (DPA) ne contiennent pas de quantitt significative de carotenoi'des colorees; elles ne sont pas aussi sensibles a la mortalit6 photodynamique que les cellules entierement pigmentees. La mortalit6 photodynamique est accompagnke par une liberation selective du magntsium et du calcium e t de materiel absorbant I'UV. En I'absence de photosensibilisateurs, M . roseus, les deux mutants, ou lcs cellules inhibks au DPA, ne sont pas tuees lorsqu'elles sont exposees a la lumitre blanche a des intensites aussi hautes que 22 000 ft-c (236 806 Im/m2) pour aussi longtemps que 9 1.1, et les cellules ne liberent pas de materiel absorbant I'UV. Sous ces conditions, M . rosetts et le mutant jaune ne liberent pas autant d...

PHOTOKILLING OF MICROCOCCUS ROSEUS

“…Procedures similar to those used here were used to demonstrate repair of photodynamic damage in Escherichia coli (Das et al, 1974). However, we were not able to substantiate the suggestion of Schwartzel and Cooney (1974b) that M . roseus has a repair mechanism.…”

“…The absorption spectrum of pigments from the wild type (Fig. 2) are typical of a mixture of canthaxanthin, echinenone, 4-hydroxyechinenone, and other pigments with a /I-carotene chromophore previously identified (Cooney et a!., 1966;Schwartzel and Cooney, 1970, 1972, 1974b. Two mutants, labeled W H and 10.5, respectively, appear to lack colored carotenoids.…”

“…The bacterium Micrococcus roseus is killed when cells are exposed to white light (3000 ft-c, 47 J/s/mz) in the presence of oxygen and a photosensitizing dye. The phenomenon, known as lethal photodynamic action (PDA), is not observed if the exogenous photosensitizing dye is omitted, even when cells are exposed for as long as 9 h to light of an intensity of 22,000 ft-c (348 J/s/m2) (Schwartzel and Cooney, 1974b). This led to the suggestions that M .…”

“…roseus synthesizes a number of carotenoids (Cooney, et al, 1966;Schwartzel and Cooney, 1970, 1972, 1974a. Cells grown in the presence of diphenylamine (DPA) do not contain significant quantities of colored carotenoids but they accumulate colorless carotenoid precursors (Schwartzel and Cooney, 1974b fore, a second objective of the present work was to obtain mutants of M . roseus which lack colored carotenoids and to compare their sensitivity to PDA with that of the pigmented parent organism in order to determine if carotenoids protect the organism against lethal PDA.…”

Oxycarotenoids in Poultry Feeds

“…Cooney et al (165), Ungers and Cooney (826), and Schwartzel and Cooney (710) reported canthaxanthin to be the major pigment in Micrococcus roseus. Canthaxanthin has its widest distribution in marine organisms.…”