HAEMOPROTEINS AND HAEM SYNTHESIS IN FACULTATIVE PHOTOSYNTHETIC AND DENITRIFYING BACTERIA

Abstract

A simple spectrophotometric method is described for the measurement of various hemoproteins in extracts of photosynthetic and non-photosynthetic bacteria. The method is based on measurements of difference spectra at the Soret maxima. In photosynthetic bacteria of the Athiorhodaceae group the concentration of carbon monoxide-binding hemoprotein and of cytochromes of the b and c types is two to three times as high in anaerobically grown cells as in those grown aerobically. During the adaptation of Rhodopseudomonas spheroides 8253 to form photosynthetic pigments the concentration of each of these hemoproteins increases in parallel with that of the bacteriochlorophyll. The carbon monoxide-binding hemoprotein in aerobically grown R. spheroides 8253, in contrast with anaerobically grown cells, is predominantly in the particulate fraction of extracts prepared by ultrasonic vibration. The b- and c-type cytochromes are approximately equally distributed between each fraction in extracts from both types of cell. Extracts of Micrococcus dentrificans grown anaerobically on nitrate contain more cytochromes of the b and c types, as well as of the carbon monoxide-binding pigment, than do those from aerobically grown cells. The activity of ferrochelatase in both R. spheroides 8253 and M. dentrificans was similar in extracts from cells grown aerobically and anaerobically, though the hemoprotein content was higher under the latter conditions. Coproporphyrinogen oxi-dative decarboxylase could not be demonstrated in cell-free extracts of either organism.