Influence of chromium (III) on the ability of Pseudomonas fluorescens to adapt to a multiple-metal stress

Abstract

Pseudomonas fluorescens was found to grow in a minimal mineral medium supplemented with millimolar aluminium, iron, zinc, calcium and gallium. The addition of 1 mM chromium slowed the growth rate and led to a dimunition in cellular yield at stationary phase of growth. A 23% and 38% decrease in biomass was observed in the metal stressed cultures as compared to the control. Citrate, the sole cabon source, was completely utilized albeit a different rates. At stationary phase of growth most of the test metals were immobilized in an insoluble deposit that comprised of phosphatidylethanolamine (PE). Ultracentrifugation and dialysis experiments revealed that the test metals were associated with (PE) from an early stage of growth. This microbial model may have potential application in bioremediation processes. When chromium was the only test metal, it was predominantly localized in soluble form(s) in the spent fluid.