Exocellular and intracellular accumulation of lead in Pseudomonas fluorescens ATCC 13525 is mediated by the phosphate content of the growth medium |
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Authors: | Ala Al-Aoukaty Vasu D Appanna John Huang |
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Institution: | Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada. |
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Abstract: | Pseudomonas fluorescens appears to elicit disparate lead detoxification mechanisms in phosphate-rich and phosphate-deficient media. When grown in the presence of 0.1 mM Pb2+ complexed to citrate, the sole source of carbon, only a slight diminution in cellular yield was observed in the former medium. However, in a phosphate-deficient milieu, lead imposed approximately a 30% reduction in bacterial multiplication. At stationary phase of growth, 72% of the metal was found in the bacterial cells from the phosphate-deficient medium, while that from phosphate-rich broth contained only 12.5%. The latter medium was characterized by an insoluble pellet that accounted for 73.5% of the lead. Although no citrate was detected in the phosphate-rich media after 40 h of incubation, only 72% of citrate was consumed even after 70 h of growth in the phosphate-deficient cultures. The inclusion of lead did not appear to enhance the production of either extracellular proteins or carbohydrates. |
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Keywords: | Lead detoxification Bioaccumulation Bioprecipitation Citrate Phosphate Pseudomonas fluorescens |
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