INFLUENCE OF CALCIUM OR MANGANESE ON THE RESISTANCE TO EDTA, POLYMYXIN-B OR COLD SHOCK, AND THE COMPOSITION OF PSEUDOMONAS-AERUGINOSA GROWN IN GLUCOSE-DEPLETED OR MAGNESIUM-DEPLETED BATCH CULTURES

Cultures were batch grown in simple salts media in which growth was limited either by depletion of glucose and magnesium (C/Mg‐dep) or by glucose alone (C‐dep). Cultures were also grown in these media supplemented by calcium and/or manganese. All cultures grown in the C‐dep media were sensitive to ethylenediaminetetraacetic acid (EDTA), polymyxin and also to cold shock but were relatively resistant to ethyleneglycol‐bis(2‐aminoethyl ether)‐N, N‐tetraacetic acid (EGTA). Inclusion of calcium or manganese in the growth medium enhanced lysis by EDTA. Cultures grown in the basic C/Mg‐dep media were resistant to EDTA, EGTA, polymyxin and to cold shock. Sensitivity to these agents was retained by cultures grown in C/Mg‐dep media supplemented with Ca2+ and/or Mn2+. Cells grown in C/Mg‐dep media with added Mn2+ were more sensitive to EDTA and polymyxin than those from the unsupplemented C/Mg‐dep media but still resistant compared with C‐dep cultures. All cultures from supplemented C/Mg‐dep media were more sensitive to EGTA than those from any of the C‐dep media. Whole cells and cell walls from these various media had differing amounts of cell wall, phosphorus, amino sugar, carbohydrates, readily extractable lipid (REL), total phospholipid (PL), and especially differences in cell wall divalent metal cation content. The differences in PL, REL and amino sugars and carbohydrate did not correlate with the response of C‐dep and C/Mg‐dep bacteria to EDTA, EGTA or polymyxin. The results are discussed in relation to the hypothesis that the sensitivity of Pseudomonas aeruginosa to polymyxin and EDTA is more dependent on outer membrane cation content rather than on other components, e.g. PL and lipopolysaccharide. Copyright © 1979, Wiley Blackwell. All rights reserved