Intracellular inclusions of a n-alkane-grown Arthrobacter

The ultrastructural changes associated with the growth of a marine Arthrobacter sp. on n-hexadecane were demonstrated by transmission electron microscopy. Multiple electron translucent areas (ETI), similar to inclusions described by other investigators, were found in hydrocarbon-grown cells but not in peptone-grown cells. Stereological planimetry demonstrated that the ETI occupy as much as 40% of the hydrocarbon-grown cell's volume. Electron dense structures (EDI) were observed in hexadecane and in peptone-grown cells. Gas chromatographic analysis indicated traces of n-hexadecane associated with the hydrocarbon-grown cells: however, the hydrocarbon levels were not high enough to suggest the presence of hydrocarbon inclusions in the cells. Solvent partition studies with disrupted 14C-n-hexadecane-grown cells suggested that the intracellular radioactivity was associated with polar compounds. Acrylate-inhibited, hydrocarbon-grown Arthrobacter sp. did not form ETI, suggesting that the formation of ETI involves the participation of Coenzyme A. Thin-layer and gas chromatography indicated that the major intracellular components were glycerides, with one or more R groups composed of palmitic acid and free palmitic acid. 27 references, 5 figures, 2 tables