Cadmium biosorption and toxicity to laboratory ‐ grown bacteria

Abstract

Cadmium uptake by Pseudomonas fluorescens cells could be described by a Freundlich isotherm suggesting that adsorption was the major process of cadmium uptake by bacteria. Standardization of culture conditions appears to be necessary as a 30 per cent difference was obtained in cadmium uptake for bacteria grown for 15h and 14.5h respectively. Cadmium concentration inhibiting 50 per cent of growth rate and biomass production or increasing the lag phase by a factor 2 was approximately 3 ppm for a first exposure of Ps. fluorescens. The use of two Klebsiella aerogenes strains (high and low capsule producers) confirmed a protective effect of exopolysaccharides against cadmium.

Treatment Petroleum Oil Contaminated Soil by Inoculation of Different Bacterial Strains

“…The microbial population is directly affected by this lethal concentration. Similar results for bacterial counts have also been reported by Atlas (1981), Wang (1984), Bauda and Block (1985), Pettibone and Cooney (1988) and Odokuma and Dickson (2003). Further increase in duration of incubation period for hydrocarbon degradation resulted in reduction in number of bacteria in all the inoculated soil samples which may be attributed to reduction in the amount of available nutrients required for bacterial growth and altered physico-chemical conditions of soil.…”

Bacterial sorption of heavy metals

“…DISCUSSION The objective of this research was to evaluate the metal sorption capacities of selected gram-positive and gramnegative bacteria and to determine whether Freundlich adsorption isotherms might be useful for evaluating bacterial metal binding. Although adsorption isotherms have been traditionally used to describe stoichiometric solute-solid interactions, such as adsorption, chemisorption, and ion exchange, they have also been used to describe the removal of various cations from a range of solution concentrations by microorganisms and bacterial exopolymers (1,7,14,23,24). However, when using intact bacterial cells, one must consider that other processes besides surface adsorption could occur.…”

Role of envelopes of gram‐negative bacteria in cadmium binding and toxicity

“…An equal number of cells were exposed to cadmium (final pmolar concentrations of cadmium 0.89, 8.9, and 89) for 1 h at 4°C on a rotary shaker (100 rpm). This contact time was chosen from previous results (Bauda and Block, 1985). The bacterial cells were then harvested from the 3-mL samples by centrifugation at 2500 x g for 10 min, and the cadmium concentration in the supernatant was measured twice on three aliquots using a flameless atomic absorption spectrophotometer (Perkin Elmer 305 B).…”