Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6309898 | Chemosphere | 2014 | 6 Pages |
Abstract
The current study aimed to characterize Arthrobacter sp. Sphe3 ability to reduce Cr(VI) in suspended cell cultures as well as in immobilized form using Ca-alginate beads. Adaptation studies in the presence of 5 mg Lâ1 Cr(VI) showed a significant increase in specific growth rate from 0.25 to 0.3 hâ1 and bioremoval percentage from 64% to 94% (p < 0.05), whereas Arthrobacter sp. Sphe3 could tolerate up to 50 mg Lâ1 Cr(VI). Optimization of culture conditions resulted in complete reduction of 45 mg Lâ1 Cr(VI) at 30 °C, pH 8 and 10 g Lâ1 of glucose. High glucose concentrations helped at reducing (80 ± 2.4)% of initial 100 mg Lâ1 Cr(VI), whereas the bacterial strain could tolerate 850 mg Lâ1 Cr(VI). Cr(III) formation was first evidenced by the appearance of a green insoluble precipitate in the medium. Cell biomass was successfully immobilized in Ca-alginate beads that were evaluated for their stability. Cell release was sharply decreased when 4% Na-alginate was used under non-shaking conditions. Biotransformation efficiency was enhanced when 25-50 mg cells mLâ1 Na-alginate from the exponential growth phase were collected and co-encapsulated with either 1% glucose and 0.5% (NH4)2SO4, or 1% LB medium. Immobilized biocatalyst could be reused up to 6 continuous cycles in the presence of 10 mg Lâ1 Cr(VI), but its performance was lowered at higher metal concentrations comparing with free cells that significantly maintained their reducing ability up to 300 mg Lâ1 Cr(VI).
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Authors
M.G. Ziagova, A.I. Koukkou, M. Liakopoulou-Kyriakides,