The spectrum of bacteriochlorophyll in vivo: observations on mutants of Rhodopseudomonas spheroides unable to grow photosynthetically.

Abstract

Abstract— The major blue pigment from a mutant of Rhodopseudomonas spheroides that is unable to grow photosynthetically has been compared with authentic bacteriochlorophyll. By the following criteria the pigments are identical: chromatographic behavior; visible and i.r. epectra of the pigments and of their Mg‐free derivatives in a varity of solvents; reaction in the Molisch phase test; isolation of phytol.The spectra in vivo in the region of bacteriochlorophyll absorption of the following strains grown under a variety of conditions have been compared:(a) wild‐type (strain Ga), (b) photosynthetically deficient mutant (strain PM‐8), (c) secondary mutants derived from PM‐8 lacking colored carotenoid pigments, and (d) carotenoid‐less, photosynthetically competent revertants from strains of type (c). It is concluded (1) that the spectrum of reaction center bacteriochlorophyll (P870) includes an absorption band at 805 mμ as well as at 870 mμ and (2) that the relative heights of the three absorption bands of bulk bacteriochlorophyll (at 805, 850 and 875 mp) are strongly influenced by the presence of P870.