Influence Of Different Minerals On The Formation Of Magnetosomes In Acidithiobacillus Ferrooxidans YN-3

Magnetotactic bacteria(MTB) is the name of all kinds of prokaryotes with magnetotaxis, which containing Nano-particles--the magnetosomes. Magnetosomes is an ideal kind of bio-nano-magnetic material, because of its specific properties such as superior crystalline, well biocompatible, uniform nano-sized, non-agglomerated and specific magnetic characteristics.The researchers in this group discovered the fact that the Acidithiobacillus ferrooxidans could synthesize intracellular electron-dense magnetic particles and this study researched the effect of formation of magnetosomes in bioleaching bacteria under different minerals.Acidithiobacillus ferrooxidans strainYN-3 was used to reach the effect of physiological characteristics and the change of magnetotaxis under different minerals including pyrite, chalcopyrite, pyrrhotite and sphalerite. The results showed that the physiological characteristics of bacteria had become great difference because of the effect of different minerals.The growth rate of YN-3 was fastest when sphalerite was the source of energy, the next was pyrrhotite and chalcopyrite, YN-3 had the lowest growth rate under the effect of pyrite. Semi-solid flat-panel magnetophoresis indicated that the bacteria were able to orient and migrate to the magnet in artificial magnetic field when pyrite and pyrrhotite as the energy, but there was no such phenomenon when sphalerite and chalcopyrite were energy.Analyze the response of mpsA, magA, thy and mamB genes of YN-3 under pyrite, chalcopyrite, pyrrhotite and sphalerite by using Real-time PCR. The result of Realtime-PCR showed that these four genes had higher expression under the effect of pyrrhotite and pyrite. On the other hand, because of pyrite is hard to oxidize, the bacteria is difficult to use it as energy. As a result, the growth of YN-3 was slow, it was hard to cultivate on a large scale. According to the factors of physiological characteristics and magnetotaxis of bacteria, we can calculated that pyrrhotite was the best energy mineral for the formation of magnetosomes in YN-3.In this paper, different concentration of pyrrhotite was used to find the effect of concentration of pyrrhotite to YN-3 on the growth and the formation of magnetosomes. In the experiment, pyrrhotite concentration was 1%,2%,3%,4%,5%. The growth curve showed that YN-3 grew fastest when pyrrhotite concentration was 3%, it had the lowest growth rate with the concentration was 5%. Real-time PCR results showed that the expression of mpsA, magA, and mamB gene tended to increase with the increase of concentration of pyrrhotite. When concentration was 1% to 3%, the expression was increased significantly. While,4% to 5%, the increase tended to be gently. The expression of thy gene had no obvious change with the increase of concentration of pyrrhotite. The growth curve and the result of Real-time PCR showed that 3% was the optimum concentration of pyrrhotite for YN-3.