Effect of arsenite on the physiological and cytological properties of Pseudomonas putida strains capable of degrading polycyclic aromatic hydrocarbons

Some physiological and cytological properties of Pseudomonas putida strains resistant to arsenite and capable of degrading polycyclic aromatic hydroca rbons were studied. The resistance of P. putida BS202 (NPL-1) to arsenite p roved to be determined by chromosomal genes, while the arsenite resistance of P. putida BS238 (pBS2; pBS3031), by plasmid-borne genes. Arsenite affect ed the pattern and rate of growth of strain BS202 (NPL-I) in media with nap hthalene or salicylate as carbon sources; particularly, it lengthened the l ag phase. Electron-microscopic analysis of the strains studied did not reve al any arsenite-induced destructive changes in the cell envelope. At the sa me time, arsenite in the growth medium induced some alterations in the stru cture of the outer membrane of strain BS202 (NPL-I) and the cytoplasmic mem brane of strain BS238 (pBS2; pBS3031) and, in both strains, led to an incre ase in the density of intramembrane particles on the EF face of the freeze- fractured cytoplasmic membrane. Arsenite resistance evidently protects cell s of both strains from greater damage. Physiological and cytological data s uggest that the mechanisms of arsenite resistance in the strains studied ar e different.