EMCB-ENVIS Node ENVIRONMENTAL BIOTECHNOLOGY

EMCB-ENVIS Centre
glyoxalase I, while GSH peroxidase Se-independent enzyme and GSH reductase showed no
significant variation in activities. The increase in the enzymes activities of catfish, involved in
the inactivation of reactive molecules formed during oxidative stress, could provide an additional
protection against the oxidative damage induced by mercury.
Aran Incharoensakdi, Pissopa Kitjaharn. (Laboratory of Biochemical Products, Department
of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand).
Zinc Biosorption from Aqueous Solution by a Halotolerant Cyanobacterium
Aphanothece halophytica. Current Microbiology, 45(4) (2002), 261 – 264.
We have investigated the characteristics of zinc biosorption by Aphanothece halophytica. Zinc
could be rapidly taken up from aqueous solution by the cells with an equilibrium being reached
within 15 min of incubation with 100 mg Lm1 ZnCl2. The adsorbed zinc was desorbed by
treatment with 10 mM EDTA. The presence of glucose, carbonyl cyanide mchlorophenylhydrazone
(CCCP), and N,N'-dicyclohexylcarbodiimide (DCCD) did not affect the
uptake of zinc. The specific uptake of zinc increased at low cell concentration and decreased
when cell concentration exceeded 0.2 g Lm1. The binding of zinc followed Langmuir isotherm
kinetics with a maximum zinc binding capacity of 133 mg gm1 and an apparent zinc binding
constant of 28 mg Lm1. The presence of an equimolar concentration of Mn2+, Mg2+, Co2+, K+,
or Na+ had no effect on zinc biosorption, whereas Ca2+, Hg2+, and Pb2+ showed an inhibitory
effect. The biosorption of zinc was low at a pH range from 4 to 6, but increased progressively at
pH 6.5 and 7.
B. Clasona, W. J. Langstonb, G. -P. Zauke. (Carl von Ossietzky Universität Oldenburg,
Institut für Chemie und Biologie des Meeres (ICBM), Postfach 2503, D-26111, Oldenburg,
Germany. Marine Biological Association, Citadel Hill, Plymouth PL1 2PB, UK).
Bioaccumulation of trace metals in the amphipod Chaetogammarus marinus
(Leach, 1815) from the Avon and Tamar estuaries (UK): comparison of twocompartment
and hyperbolic toxicokinetic models. Water Research, 37(10) (2003),
2505-2511.
Bioaccumulation of Cd, Cr, Cu, Co, Pb, Ni and Zn was investigated in the eulittoral
gammaridean amphipod Chaetogammarus marinus (Leach, 1815) from the Avon and Tamar
estuaries (UK). The main goals were to provide information on accumulation strategies of the
organisms tested and to verify toxicokinetic models as a predictive tool. The organisms
accumulated metals upon exposure and it was possible to estimate significant model parameters
of two-compartment and hyperbolic models, with the exception of Zn. Both types of models
yielded significant model estimates in two independent toxicokinetic studies using gammarids
from the Avon and Tamar estuaries, respectively. Kinetic BCFs at theoretical equilibrium were
58–102 for Cd, 95–215 for Cr, 400–963 for Cu, 38–59 for Co, 150–750 for Pb and 33–63 for Ni,
and were in most cases distinctly lower than the range reported in the literature for other
amphipods. To demonstrate the potential of toxicokinetic models as a predictive tool, attempts
were made, further to verify time-dependent model data (Tamar) with independent experimental
data (Avon). In this case only for Cd were both in good agreement, whilst for all other elements
the models overestimated the measured values. The second approach was to verify timedependent
model data (Tamar) with measured values from an independent concentrationdependent
uptake study (Tamar) or, alternatively, to estimate the model parameters
simultaneously for both studies. A good agreement between observed and predicted values was
obtained for all elements for the simultaneous two-compartment models. Only for Cd was a
simultaneous estimation of the hyperbolic model more promising. A tentative estimation showed
the following sequence of sensitivity of C. marinus to an increase of soluble metal exposure: 0.6
g Cd l-1, 1.7 g Cr l-1, 16 g Cu l-1, 3.5 g Co l-1, 0.8 g Pb l-1 and 7 g Ni l-1. Available
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