The Establishment Of The Gene Transfer System In Magnetotactic Bacterium AMB-1, And Its Functional Gene Cloning And Expression

Magnetotactic bacterium are motile, mostly aquatic prokaryotes that swim along geomagnetic field lines. All magnetotactic bacteria synthesize unique intracellular structures called magnetosomes, which are nanometer-sized, membrane-bound magnetic particles consisting of the iron mineral magnetite (Fe₃O₄) (Bazylinski 1995; Balkwill et al. 1980). The unique characteristics of bacterial magnetosomes have attracted a broad interdisciplinary research interest. Their superior crystalline and magnetic properties make them potentially useful as a highly ordered biomaterial in a number of applications, e.g. in the immobilization of bioactive compounds, magnetic drug targeting, and as contrast agent for magnetic resonance imaging (Schu|¨ler and Frankel 1999).AMB-1 is a facultative anaerobic magnetotactic bacterium Magnetospirillum sp. strain , (ATCC 700264). To further understand the mechanisms of magnetosome systhesis and other relative processes, we tried to establish a high-efficiency gene transfer system in AMB-1, and also tried to clone and express its SOD and FeR genes, considering their potential involvement in the unique growth characteristics and magnetosome synthesis, respectively. SDS-PAGE and activity assay revealed that the expressed SOD had a Mr 25kD and the purified SOD displayed superoxide dismutase activity. The following are the main research contents and results:1. The establishment of a Gene transfer system based on electroporationGenomic DNA of AMB-1 was extracted and was partially digested by restrictionenzyme Sau3AI, and fragments were then ligased with plasmid pSL1180 by T4 DNAligase. The constructed plasmids were transformed into AMB-1 througelectroporation method. Changing some important effecting factors, like voltage, cell...