Localization by Electron Microscopy of Alkylsulphatases in Bacterial Cells

Alkylsulphatases have been localized in cells of two bacterial isolates using transmission electron microscopy. Cells were incubated with the appropriate alkyl sulphate ester in the presence of Ba2+ ions. Inorganic sulphate liberated by alkylsulphatases was precipitated at the site of liberation as BaSO4. Electron microscopy of thin sections was used to locate electron-dense grains which were identified by energy dispersive analysis of X-rays (EDAX) as BaSO4. The long-chain primary alkylsulphatases of the detergent-degrading bacterium Pseudomonas C12B, active on C6-C14 primary alkyl sulphates, were located on the outer cell-wall. There was no activity inside the cells. In contrast, the short-chain (C3-C7) alkylsulphatase in a coryneform isolated for its ability to grow on but-1-yl sulphate was located entirely in the cytoplasm. The butylsulphatase was apparently associated with granules of poly-β-hydroxybutyric acid. The different locations for the long- and short-chain alkylsulphatases may be related to the relative potential toxicities of their ester substrates.