Nickel uptake by Pseudomonas aeruginosa : Role of modifying factors

Pseudomonas aeruginosa cells growing in minimal medium were 40-fold more sensitive to Ni2+ than cells growing in enriched medium, suggesting a possible protective role of medium ingredients. Likewise, cells pre-grown in enriched medium showed a high Km (6.15 mM) and increased Ni2+ uptake (950 nmol m...

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Bibliographic Details
Published in:Current microbiology 1998-11, Vol.37 (5), p.306-311
Main Authors: SAR, P, KAZY, S. K, ASTHANA, R. K, SINGH, S. P
Format: Article
Language:English
Subjects:
Bacteriology
Biological and medical sciences
Carbon sources
Cations, Divalent - pharmacology
Culture Media
Dicyclohexylcarbodiimide - pharmacology
Fundamental and applied biological sciences. Psychology
Glucose - pharmacology
Hydrogen-Ion Concentration
Ion Transport - drug effects
Kinetics
Microbiology
Nickel
Nickel - metabolism
Permeability, membrane transport, intracellular transport
Phenols
Pseudomonas aeruginosa
Pseudomonas aeruginosa - growth & development
Pseudomonas aeruginosa - metabolism
Soil Microbiology
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Summary:Pseudomonas aeruginosa cells growing in minimal medium were 40-fold more sensitive to Ni2+ than cells growing in enriched medium, suggesting a possible protective role of medium ingredients. Likewise, cells pre-grown in enriched medium showed a high Km (6.15 mM) and increased Ni2+ uptake (950 nmol mg-1 protein, 1h) over cells pre-sown in minimal medium (Km, 0.48 mM; 146 nmol mg-1 protein, 1 h). The overall pattern indicates that cells pre-grown in enriched medium were characterized by having lowered affinity towards Ni2+ than those with minimal medium background. The enhanced Ni2+ uptake by enriched medium-grown cells can be correlated with the improved metabolic state of the cells. Ni2+ uptake was optimum at neutrality (pH 7.0). A major Ni2+ transport system was competitively inhibited by Mg2+, Zn2+, Cd2+, or Co2+ (400 microM each). Noticeably, a minor Ni2+ transport pathway was still operative even in the higher concentration range of Mg2+ (4 mM and 40 mM). The stimulation of Ni2+ uptake monitored in the presence of different carbon sources (0.5% wt/vol, each) showed the sequence: glucose (1.6-fold) > phenol = gallic acid (1.5-fold). Succinate, in comparison, reduced Ni2+ uptake (0.5-fold) possibly because of its acting as a metal chelator as well. Sensitivity of Ni2+ transport towards methyl viologen, azide, 2-4 DNP, and DCCD suggested that transport was energy-linked.
ISSN:0343-8651
1432-0991
DOI:10.1007/s002849900383