title: Characterization of intracytoplasmic hydrocarbon inclusions from the hydrocarbon-oxidizing Acinetobacter species HO1-N.
abstract: The ultrastructure of Acinetobacter sp. strain HO1-N grown on hydrocarbon and nonhydrocarbon substrates was compared using thin sections and freeze-etching. Hydrocarbon-grown cells were characterized by the presence of intracytoplasmic membrane-bound hexadecane inclusions. This membrane did not exhibit a typical unit membrane structure but appeared as a monolayer. The freeze-etch technique revealed the internal structure of the hexadecane inclusions and provided evidence for the presence of a smooth-surfaced limiting membrane. Freeze-etching also revealed intracytoplasmic membranes in the hexadecane-grown cells. These ultrastructural modifications were not present in nonhydrocarbon-grown cells. The hexadecane inclusions were isolated from Acinetobacter. Negative-staining of the inclusions revealed electron-transparent vesicles approximating the size of the inclusions seen in whole cells. Freeze-etching of the purified inclusions revealed membrane-bound vesicles. The purified inclusions exhibited a relatively high value of lipid phosphorus to protein. The lipid composition and the electrophoretic banding pattern of the inclusions on sodium dodecyl sulfate-polyacrylamide gels were determined and compared with other membrane fractions (outer membrane and cytoplasmic membrane) previously isolated from this organism.
mesh_terms: D000150:Acinetobacter / Q000378:metabolism / Q000648:ultrastructure*; D000473:Alkanes / Q000032:analysis / Q000378:metabolism; D001426:Bacterial Proteins / Q000032:analysis; D002462:Cell Membrane / Q000032:analysis; D005613:Freeze Etching; D002479:Inclusion Bodies / Q000032:analysis / Q000648:ultrastructure*; D007661:Ketoses / Q000032:analysis; D008055:Lipids / Q000032:analysis; D010743:Phospholipids / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D013400:Sugar Acids / Q000032:analysis
chemical_list: D000473:Alkanes; D001426:Bacterial Proteins; D007661:Ketoses; D008055:Lipids; D010743:Phospholipids; D013400:Sugar Acids; D010758:Phosphorus