Enzyme localization in Bacillus megaterium.

Weibull (1953a) has shown that after osmotic lysis of protoplasts of Bacillus megaterium, prepared by controlled treatment with lysozyme, only two microscopically detectable structures remain; membrane-like bodies termed "ghosts," and granules. The ghosts were found to sediment as a dark yellow fraction by centrifugation at 10,000 G (Weibull, 1953b) and to contain almost all the pigmented material and cytochromes of the whole cell. The latter observation is in agreement with the particulate nature (particles sedimenting between 22,000 and 100,000 G) of the cytochrome complement of Pseudomonas fluorescens (Stanier et al., 1953; Wood, 1955), Escherichia coli (Asnis et al., 1956), and Acetobacter suboxydans (Smith, 1954). In subsequent experiments Weibull (1956a) has obtained evidence that the ghost is the cytoplasmic membrane, perhaps in a denatured form. A brief treatment of the yellow ghost fraction in the sonic oscillator destroys the ghost structure and leads to the formation of granules which could be sedimented at 105,000 G (Weibull, 1953b). The similarity in chemical and physical properties between these granules and the particulate fractions isolated after the mechanical disruption of several different types of bacteria have led Stanier (1954) to propose that "the bacterial cytochrome system, along with some other enzymes, may be a built-in part of the cell membrane, and not, as in higher organisms, a mitochondrial component." The present work supports this concept by