INDIUM DETOXIFICATION IN PSEUDOMONAS-FLUORESCENS

The interaction between indium, a non-essential toxic element, and a soil bacterium was studied. Although the presence of 0.5 mm indium complexed to citrate, the sole source of carbon, had an inhibitory influence on growth rate and cellular yield, Pseudomonas fluorescens circumvented the toxicity of the trivalent metal via its insolubilization as a phosphorus residue. The inclusion of 20 muM iron(III) arrested the negative impact of indium and no diminution of cellular yield was recorded. In this instance indium homeostasis was also attained by elaboration of an extracellular phosphorus-containing deposit. Electrophoretic analyses of the cytoplasmic extracts revealed several dissimilar patterns Notably, two polypeptides with apparent molecular masses of 57 kDa and 18 kDa were induced in the metal-stressed bacteria. An increment in extracellular carbohydrates in metal-supplemented media was observed. No citrate was detected in the spent fluid at the cessation of cellular multiplication. This model of microbial indium insolubilization may have potential application in metal pollution management.