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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

与传统的火法冶金工艺相比，生物浸铁工艺对环境的污染小，因此有望成为下一代金属冶炼工艺。然而，目前还很难找到具有较高浸出能力的铁氧化细菌。如果这种细菌存在，则生物浸出也适用于高品位矿石如浮选精矿的处理。本研究的目的是大幅度提高铁氧化细菌的能力。使用其抗汞基因偶联的载体质粒作为转化子的选择标记，检查电穿孔的条件。通过对预处理条件的设计和缓冲液的改进，使铁氧化菌Y 4 -3的转化成为可能。该菌株还被含铁氧化酶基因的载体质粒转化。但在处理过程中，铁氧化速率的提高并不明显 ...更多信息回答者检测了载体质粒的稳定性。证实即使经过10次以上的继代培养，载体DNA仍稳定存在。这种稳定性即使在汞离子不存在的条件下也是相同的。将野生型菌株与野生型菌株在同一容器中培养，分析两者的竞争关系。在不施加汞离子选择压力的情况下，培养液中汞的比例迅速下降，培养物中只剩下野生型菌株。除汞抗性基因外，银抗性基因作为一种选择标记受到关注。在10株铁氧化细菌中，E-24菌株对银的抗性最强。对菌株E-24进行了抗性机制的研究，发现了将银离子排出到体外的可能性，作为抗性机制研究的结果，预期银离子被排出到细胞外。对大肠杆菌耐银基因的克隆进行了尝试，以失败告终。少