Gluconobacter oxydans is well known for the limited oxidation of compounds and rapid excretion of industrially important oxidation products. The dehydrogenases responsible for these oxidations are reportedly bound to the cell's plasma membrane. This report demonstrates that fully viable G. oxydans differentiates at the end of exponential growth by forming dense regions at the end of each cell observed with the light microscope. When these cells were thin sectioned, their polar regions contained accumulations of intracytoplasmic membranes and ribosomes not found in undifferentiated exponentially growing cells. Both freeze-fracture-etched whole cells and thin sections through broken-cell envelopes of differentiated cells demonstrate that intracytoplasmic membranes occur as a polar accumulation of vesicles that are attached to the plasma membrane. When cells were tested for the activity of the plasma membrane-associated glycerol dehydrogenase, those containing intracytoplasmic membranes were 100% more active than cells lacking these membranes. These results suggest that intracytoplasmic membranes are formed by continued plasma membrane synthesis at the end of active cell division.

Cytological differences were observed between stationary-and exponentialphase cells of Acetobacter suboxydans grown in a defined medium. Unstained cells observed with the light microscope just after entering the stationary phase differed from exponentially growing cells in that the former exhibited localized increases in density, particularly in the polar regions. Electron microscopy of thin sections revealed that early stationary-phase cells possessed predominantly polar complexes of intracytoplasmic membranes accompanied by polar increases in ribosomal material. When cultures were allowed to continue far into the stationary phase, cells contained extensive aggregations of membrane-like material as the predominant fine-structural feature. In contrast, thin sections of exponentially growing cells exhibited only occasional indications of intracytoplasmic membranes. Intracytoplasmic membranes heretofore have been observed only rarely in the heterotrophic Pseudomonadales.

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Dihydroxyacetone was quantitatively produced from glycerol during the primary exponential growth phase and depleted during the secondary exponential phase. Although no growth was detected on the basal medium, growth occurred upon addition of dihydroxyacetone.

Naturally occurring glomerulonephritis in conventional NZB (1), AKR (2), and RF (3) mice has been associated with an immune complex etiology. In all three cases, it has been demonstrated that the glomerular lesion is a result, in part, of chronic deposition of immune complexes of endogenous Gross virus-specific cell surface and/or soluble antigens with “G natural” antibody. Glomerular lesions of this type also have been observed in AKR (4) and BALB/c (5) mice with experimentally induced leukemias, and in the latter study they were specifically associated with immune complexes involving antigens of the exogenous murine leukemia virus (MuLV).3 At the ultrastructural level, this glomerulonephritis is characterized by marked thickening of localized regions of the glomerular basement membrane (5, 6), which is thought to result from the immune complex deposition (7). We report here the localization of intact endogenous C-type virus within the basement membrane of aged AKR mice showing evidence of chronic glomerulonephritis.