Copper reduction by yeast cell wall materials and its role on copper uptake in Debaryomyces hansenii |
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| Affiliation: | 1. School of Chemical Engineering, Nanjing University of Science and Technology Nanjing, Jiangsu 210094, PR China;2. Nanjing AIREP Environmental Protection Technology Co., Ltd, Nanjing, Jiangsu 210091, PR China;3. Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), Nanjing University of Information Science & Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Nanjing, Jiangsu 210044, PR China;1. Department of Civil Engineering Technology, Faculty of Civil Engineering Technology, Universiti Tun Hussein Onn Malaysia, Pagoh Education Hub, 84600, Pagoh, Muar, Johor, Malaysia;2. Advanced Technology Centre, Faculty of Engineering Technology, Universiti Tun Hussein Onn Malaysia, Pagoh Education Hub, 84600, Pagoh, Muar, Johor, Malaysia;3. Department of Production and Operation Management, Faculty of Technology Management and Business, Universiti Tun Hussein Onn Malaysia, 86400, Parit Raja, Batu Pahat, Johor, Malaysia;4. Department of Chemical Engineering, Faculty of Engineering Technology, Universiti Tun Hussein Onn Malaysia, Pagoh Education Hub, 84600, Pagoh, Muar, Johor, Malaysia;1. Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia;2. Faculty of Petroleum and Renewable Energy Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia;3. Rubber Research Institute of Malaysia, Malaysian Rubber Board, Technology and Engineering Division, Rubber Research Institute of Malaysia, Malaysian Rubber Board, 47000 Sungai Buloh, Selangor, Malaysia |
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| Abstract: | Copper binding reducing activities of cell wall materials (CWM) prepared from cells of the yeast Debaryomyces hamsenii were examined. When CWM was treated with copper sulfate (0.1 mM CuSO4), the copper was partially reduced from Cu (II) to Cu (I) and bound to CWM (below 10 nmol per mg dry wt.). The bound copper was mostly in the fraction of mannan-protein. Both copper-binding ability and protein content decreased with protease treatments. Mannan-protein prepared from CWM bound more copper than mannan did. This suggests that Cu (II) bound to the protein portion in CWM and was reduced to Cu (I). The optimum pH of copper reduction by CWM was about 5.0. The amount of copper bound to CWM increased with reducing agents and decreased with oxidizing agents. On the other hand, the copper uptake by yeast whole cells and spheroplasts was also stimulated by reducing agents, but inhibited by oxidizing agents. Furthermore, copper uptake by spheroplasts was stimulated in the presence of CWM. The optimum pH of copper uptake coincided with that of copper reducing activity. These results suggest that yeast cell wall not only supplies copper binding but also reduces copper, and the reduced copper is transported into yeast cells. The yeast cells may have copper-reducing proteins in the cell wall. |
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