3.3. Effect of initial metal ion concentration on growth and metal ion bioaccumulation
The growth of A. lentulus was significantly influenced by the initial metal ion concentration ( Table 1). In case of the control, the stationary growth phase was achieved after 3 d due to exhaustion of glucose (data not shown). However, the growth was delayed in the presence of metal ions resulting in an extended lag phase. During this period, the fungus adapted to metal ions. Lower biomass production was observed in the presence of metals as compared to the control. Percent reduction in biomass in the presence of Ni(II) ions was increased from 19 to 76% (at 70–140 mg L−1), while in the presence of Cu(II) ions it was increased from 16 to 77% (at 80–800 mg L−1) after 5 d of the growth. Cr(III) ions showed least inhibition (35% at 5000 mg L−1) whereas in the presence of 1000 mg L−1 Pb(II) ions, 40% growth inhibition was observed. Considering the exposed metal concentration, Ni(II) caused a higher growth inhibition than Cu(II) followed by Pb(II) and Cr(III). Similar results were also observed by Moore et al. (2008), who had reported that Cu(II) and Ni(II) causes a significant inhibitory effect on the biomass production. Donmez and Aksu (2001) have also reported the reduction in the biomass growth rate both for adapted (from 3.84 d−1 to 1.42 d−1) and non-adapted (from 3.84 d−1 to 1.1 d−1) Candida sp. in the presence of 578.7 mg L−1 Cu(II) ions. A more severe reduction in the growth rate was observed for both the adapted (from 2.4 to 0.3 d−1) and non-adapted (3.36–1.1 d−1) Candida sp. in the presence of 63.6–375.8 mg L−1 Ni(II) ion.
3.3. Effect of initial metal ion concentration on growth and metal ion bioaccumulationThe growth of A. lentulus was significantly influenced by the initial metal ion concentration ( Table 1). In case of the control, the stationary growth phase was achieved after 3 d due to exhaustion of glucose (data not shown). However, the growth was delayed in the presence of metal ions resulting in an extended lag phase. During this period, the fungus adapted to metal ions. Lower biomass production was observed in the presence of metals as compared to the control. Percent reduction in biomass in the presence of Ni(II) ions was increased from 19 to 76% (at 70–140 mg L−1), while in the presence of Cu(II) ions it was increased from 16 to 77% (at 80–800 mg L−1) after 5 d of the growth. Cr(III) ions showed least inhibition (35% at 5000 mg L−1) whereas in the presence of 1000 mg L−1 Pb(II) ions, 40% growth inhibition was observed. Considering the exposed metal concentration, Ni(II) caused a higher growth inhibition than Cu(II) followed by Pb(II) and Cr(III). Similar results were also observed by Moore et al. (2008), who had reported that Cu(II) and Ni(II) causes a significant inhibitory effect on the biomass production. Donmez and Aksu (2001) have also reported the reduction in the biomass growth rate both for adapted (from 3.84 d−1 to 1.42 d−1) and non-adapted (from 3.84 d−1 to 1.1 d−1) Candida sp. in the presence of 578.7 mg L−1 Cu(II) ions. A more severe reduction in the growth rate was observed for both the adapted (from 2.4 to 0.3 d−1) and non-adapted (3.36–1.1 d−1) Candida sp. in the presence of 63.6–375.8 mg L−1 Ni(II) ion.
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