Influence of nutrient limitation of growth on stability and production of virulence factors of mucoid and nonmucoid strains of Pseudomonas aeruginosa

Abstract

The stability of and production of extracellular virulence factors by mucoid (M7) and nonmucoid (wild-type) strains of Pseudomonas aeruginosa were studied in batch culture and in chemostats. Chemostat cultures were nutrient limited by iron, carbon, nitrogen, phosphorus, magnesium, and sulfur at various growth rates. Both M7 and wild-type strains were relatively stable in simple salts media. The wild type gave rise to one variant and M7, to several. M7 was most stable under iron limitation. Chemostat production of extracellular polysaccharide, protease, elastase, lipase, and phospholipase C all varied in a complex manner with growth conditions.