Laboratory of Food Chemistry and Nutrition, College of Food Science and Engineering, Ocean University of China, Qingdao, China.
Department of Computer Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.
J Basic Microbiol. 2019 Sep;59(9):867-878. doi: 10.1002/jobm.201900272. Epub 2019 Jul 26.
Removal of heavy metals from food material by growing micro-organisms is limited by the toxicity to cells. In this study, different preincubation treatments were investigated to analyze their effects on cadmium resistance and removal ability of Pichia kudriavzevii A16 and Saccharomyces cerevisiae CICC1211. Sucrose preincubation improved the cadmium resistance of both yeast cells and increased the cadmium-removal rate of P. kudriavzevii A16. An evident decrease of intracellular and cell-surface cadmium accumulation was observed after sucrose preincubation, which may be the primary reason responsible for the improved cadmium resistance. Flow cytometry assay showed that sucrose significantly reduced the production of reactive oxygen species (ROS) and cell death rate of both yeasts under cadmium compared with those normally cultured cells. Under cadmium stress, the content of both protein carbonyls and malonyldialdehyde were also reduced by the addition of sucrose, the results were in accordance with the tendency of ROS, exhibiting a defending function of sucrose. Osmotic regulators as proline and trehalose were increased by sucrose preincubation in P. kudriavzevii A16 in the presence of cadmium. The results suggested that sucrose preincubation could be applied to improve cadmium resistance and removal rate of yeasts.
利用生长中的微生物从食物材料中去除重金属受到细胞毒性的限制。在这项研究中，研究了不同的预孵育处理方法，以分析它们对毕赤酵母 A16 和酿酒酵母 CICC1211 的镉抗性和去除能力的影响。蔗糖预孵育提高了酵母细胞的镉抗性，并提高了毕赤酵母 A16 的镉去除率。蔗糖预孵育后，观察到细胞内和细胞表面的镉积累明显减少，这可能是提高镉抗性的主要原因。流式细胞术检测表明，与正常培养的细胞相比，蔗糖显著降低了镉胁迫下两种酵母的活性氧（ROS）产生和细胞死亡率。在镉胁迫下，添加蔗糖还降低了蛋白质羰基和丙二醛的含量，这与 ROS 的趋势一致，表现出蔗糖的防御功能。在存在镉的情况下，蔗糖预孵育增加了毕赤酵母 A16 中的渗透调节剂脯氨酸和海藻糖。结果表明，蔗糖预孵育可用于提高酵母的镉抗性和去除率。
