Scanning electron microscopy of L-phase streptococci. II. Growth in broth and upon Millipore filters

Abstract

The growth of L-phase streptococci in broth and upon Millipore membrane filters was studied by light and scanning-beam electron microscopy. Osmotic sensitivity, shape, size, and surface features of L-phase bodies, ratios of large bodies to granules, and number of units in clusters varied with the phase of growth in broth. During the lag phase of growth the L-phase elements seemed to possess a weakened membrane as suggested by their increased susceptibility to osmotic lysis and their flattened shape. Irregular protuberances, which may be associated with formation of elementary corpuscles or degeneration of membrane, were found on large bodies in stationary phase. Replication in broth appeared to occur by single budding of large bodies or binary fission of granules measuring 0.7 μm or more in diameter. L-Phase colonies of group D streptococci, strains F24 and Z30, and group A streptococci, strains ADA, AED, and GL8, were differentiated by morphology when grown on Millipore membrane filters pressed upon uniform agar medium. Both group and strain variation were observed.