Intracellular location of carotenoid pigments and some respiratory enzymes in Sarcina lutea.

The study of the analytical cytology of the bacterial cell was initiated with the work of Schachman et al. (1952), which revealed the presence of a variety of particles in extracts of many microorganisms. Since that time, numerous workers have isolated and characterized some of these particles. This work has been thoroughly reviewed by Alexander (1956). More recent studies (Cota-Robles et al., 1958; Tissieres and Watson, 1958) suggest that these various particles may be divided into two broad categories. The first includes large particles with which are associated a variety of enzymatic activities, often respiratory in nature. The second includes small particles, rich in ribonucleoprotein. The chromatophores of photosynthetic bacteria represent perhaps a third and distinct type. Until recently, little could be said about the origin or intracellular location of any of these kinds of particles; in particular it was unclear whether particles of the first kind, the "respiratory" particles, existed in the particulate state within the cell, or whether they were artifacts of cell breakage. Weibull (1953), on the basis of experiments with protoplasts of Bacillus megaterium, suggested that the entire cytochrome content of the cell is associated with the cell membrane. Stanier (1954) made a more precise and general statement of this hypothesis, and suggested that the particles found in extracts of mechanically disrupted cells, with which are associated respiratory enzymes, are derived from the membrane by comminution. More recently, Marr and Cota-Robles (1957), Storck and Wachsman (1957), and Mitchell and Moyle (1956) have presented evidence supporting the