Effects of Exogenous Phospholipase A_2 and C on Phospholipids in Whole Cells of Escherichia coli JE1011 and Its NS Mutants

Whole cells of Escherirhia coli JE 1011 and its novobiocin-supersensitive (NS) mutants were treated with exogenous phospho!ipase A_2 and C. The phospholipids in whole cells of JE 1011 were scarcely hydrolyzed by the phospholipases, whereas those of NS mutants including NS6 with complete lipopolysaccharide (LPS) were extensively hydrolyzed. The accessibility of phospholipids in whole cells to exogenous phospholipases bore no relation to the composition of phospholipids in these strains. When the cells of JE 1011 were frozen-thawed or treated with ethylenediaminetetraacetate (EDTA), the phospholipids were hydrolyzed by the phospholipases to the extent similar to those of NS mutants. Parent strain JE 1011 was resistant to hydrophobic substances such as tripropyl- and tributyl-tin. gentian violet and esters of p-hydroxybenzoic acid, however, the strain became sensitive to these compounds by EDTA-treatment. On the other hand, all of the NS mutants were sensitive to them. From these results, it was suggested that the accessibility of phospholipids in whole cells to the exogenous phospholipases related to the permeability of hydrophobic substances