Molecular Breeding of High Ability Iron-oxidizing Bacteria

高能力铁氧化细菌的分子育种

基本信息

批准号：
11450392
负责人：
INOUE Chihiro
金额：
$ 9.54万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Since the load to the environment is smaller than conventional pyrometallurgy process, bioleaching process using iron-oxidizing bacteria is expected as a next-generational metal smelting process. However, it is difficult to find the iron-oxidizing bacteria with high bioleaching ability. If such bacterium exists, the bioleaching becomes also applicable the processing of high-grade ore such as the flotation concentrate. The purpose of this study is to drastically improve the ability of iron-oxidizing bacteria. Using vector plasmids of which the mercury resistance gene was coupled as a selectable marker of transformants, the condition of the electroporation was examined. By contrivance of the pretreatment condition and improvement on the buffer solution, it was possible to transform the iron-oxidizing bacterium, strain Y4-3. This strain also transformed by vector plasmids containing iron oxidizing enzyme gene. However, the improvement of iron oxidizing rate could not be observed in the tr … More ansformant. The stability of vector plasmid was examined. It was confirmed that vector DNA existed stably, even if the subculture over 10 times was carried out. This stability was same even in the condition that the mercury ion did not exist. Wild type strain and the transformant were cultured in the same vessel, and both competition relation was analyzed. The ratio the transformant in the culture solution rapidly decreased, when it did not put on the selection pressure of mercury ion, and only the wild type strain remained in the culture. As a selectable marker except for the mercury resistance gene, the silver resistance gene was noticed. The strain E-24 showed the highest silver resistance in the 10 strains of iron-oxidizing bacteria tested. On strain E-24, the resistance mechanism was examined, and the possibility of discharging the silver ion to extracorporeal was found. As a result of examining the resistance mechanism, it was anticipated that the silver ion was discharged to extacellular. The cloning of the silver resistance gene to Escherichia coli was tried, and it ended in the failure. Less

由于对环境的负荷小于传统的火法冶金工艺，因此使用铁氧化细菌的生物浸出工艺有望成为下一代金属冶炼工艺，但是，很难找到具有高生物浸出能力的铁氧化细菌。由于细菌的存在，生物浸出也适用于浮选精矿等高品位矿石的加工，本研究的目的是大幅提高铁氧化细菌的利用能力。通过设计预处理条件和改进缓冲液，研究了偶联了汞抗性基因作为转化体选择标记的载体质粒的电穿孔条件，从而可以转化铁氧化细菌、菌株。 Y4-3.也用含有铁氧化酶基因的载体质粒进行转化，但在转化体中未观察到铁氧化率的提高。检测载体质粒的稳定性，即使在野生型菌株和转化体不存在的情况下进行10次传代培养，该稳定性也相同。在同一容器中培养，分析两种竞争关系，当不施加汞离子的选择压力时，培养液中转化体的比例迅速下降，并且仅野生型菌株保留在培养物中。除了汞抗性基因之外，还注意到菌株E-24在所测试的10个铁氧化细菌菌株中表现出最高的银抗性，并检查了菌株E-24的抗性机制。发现了将银离子释放到体外的可能性。通过研究抗性机制，预计银离子被释放到细胞外。将银抗性基因克隆到大肠杆菌中。曾尝试过，但以失败告终。