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The Photosensitizing Activity of Haematoporphyrin on Mollicutes

1985; Microbiology Society; Volume: 131; Issue: 9 Linguagem: Inglês

10.1099/00221287-131-9-2217

1465-2080

Giulio Bertoloni, Alessandra Viel, A Grossato, G. Jori,

Plant and animal studies

The photosensitizing activity of haematoporphyrin (HP) on Mycoplasma hominis and Acholeplasma laidlawii was studied as a function of the phase of growth and the amount of sterols in the cell membrane. Less HP was bound to cells when the membrane had a high sterol content. Both strains in the exponential but not in the stationary phase of growth were sensitive to HP treatment (above 1 microgram ml-1) in the dark. Visible light irradiation of HP-loaded cells caused in all cases a decrease of cell survival, with concomitant changes in the pattern of membrane proteins that suggested protein-protein cross-linking, and the appearance of ultrastructural alterations (rounded and lysed cells); the photosensitivity was indirectly related to the sterol content of the cell membrane. On the whole, our findings suggest that the cell membrane is a major target for HP photosensitization of mycoplasma cells.