• The Korean Journal of Mycology
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• v.19 no.4
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• pp.282-284
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• 1991

The yeast, Hansenula anomala B-7, isolated from the $Cd^{2+}$ rich soils and determined to be tolerant in the high concentration of $Cd^{2+}$ were employed in this work. Its intact cells grown in high concentration of $Cd^{2+}$ were observed to be Iysed at the early stage when transferred to a cadmium deficient broth. Its intact cells found to be not Iysed and grow well under the high concentration of $Cd^{2+}$. The Iysis of the intact cells grown at the high concentration of $Cd^{2+}$ ion was not found when the metal ions were replaced with $Cd^{2+}$ ion in the same concentration. This result indicated that Iysis of yeast cells, at least in this isolate, would be related to cell osmosis with the mineral ions added.

• Journal of Applied Biological Chemistry
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• v.60 no.2
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• pp.113-117
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• 2017

Bioremediation is a technique using microorganisms to clean up contaminated pollutants including heavy metals. It is well known that yeasts have a high capacity to remove a wide range of metals by biosorption. Therefore, this study was focused on to obtain yeast mutant that has strong tolerance to zinc (Zn), one of representative heavy metals. The Zn resistant yeast mutant (ZnR) was induced and isolated by growing yeast cells in media containing 1 mM $ZnCl_2$ and gradually increasing the concentration until 80 mM $ZnCl_2$, in which cells were adapted and survived. The induced ZnR cells showed strong tolerance to Zn stress compared with control cells. Moreover, the ZnR cells showed increased tolerance to cadmium and nickel stress but decreased tolerance to copper stress. The increased tolerance of ZnR cells to Zn stress was due to mutation of genes. This study can be useful in bioremediation of heavy metals as the metal tolerant microorganism was artificially induced in short time.

• Microbiology and Biotechnology Letters
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• v.9 no.2
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• pp.59-64
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• 1981

The cultural conditions and the intra cellular accumulation of cadmium was studied using a cadmium tolerant yeast strain B-7 which had been isolated from activated sludge collected from a zinc mining area. The organism was able to grow in a medium containing 3,000 $\mu\textrm{g}$/$m\ell$ of cadmium-ion. (C $d^{++}$) Optimum conditions for the growth of the organisms were 20~22$^{\circ}C$ and pH 5.0~8.0 under aerobic condition. The maximum cadmium accumulation was observed when the organism was grown at pH 6.0. The growth of B-7 was not affected by the addition of a silicone-based antifoamer, which stimulated the intra cellular accumulation of cadmium. The intra cellular cadmium accumulation started after the cell ceased to grow. One gram of cells accumulated 34.17mg of cadmium when the organism was grown in a medium containing 500 $\mu\textrm{g}$/$m\ell$ of cadmium and 0.2%, v/v silicone-based antifoamer at 28$^{\circ}C$ for 48 hours with shaking. About 73 % of the accumulated heavy metal by the organism was found in the cytoplasm.m.

• Korean Journal of Microbiology
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• v.34 no.4
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• pp.225-230
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• 1998

This study was carried out to investigate the effect of cadmium ion on activities of cadmium-adapted malate dehydrogenase (adapted-MDH), which is defined to be an enzyme obtained from an extreme cadmium-tolerant yeast Hansenula anomaul B-7 grown in medium containing 1 mM cadmium ion. Cadmium-nonadapted malate dehydrogenase (nonadapted-MDH), which is defined to be enzyme expressed in the cells grown in $Cd^{2+}$ -free medium was also characterized by the same manner. Activities of the adapted-MDH and the nonadapted-MDH were strongly induced to 450% and to 150% in comparision with the control examined with 1 mM $Cd^{2+}$, respectively. The adapted-MDH activity was stimulated to 147%, 150%, and 135% compared with the control analyzed with 1 mM $Zn^{2+}$, 1 mM $Mn^{2+}$, and 1 mM $Ca^{2+}$, respectively and to 925%, and 250% compared with the control analyzed in the presence of 2 mM $Cd^{2+}$, and 2.5 mM $Zn^{2+}$, respectively. Km values of the adapted-MDH and the nonadapted-MDH were calculated to be the same 6.9 mM for L-malate, respectively. The Km value of the nonadapted-MDH was not changed by $Cd^{2+}$ while Vmax of the nonadapted-MDH was increased by $Cd^{2+}$. In contrast, both the Km and the Vmax values of the adapted-MDH were changed by $Cd^{2+}$.