Function Comparison And Analysis Of Gene-cox,cup,iro Of Acidithiobacillus Ferrooxidans In Ferrous Iron Oxidation

Acidithiobacillus ferrooxidans is extreme acidophilic autotrophic sulfur bacteria. It is widely distributed in the sulfide ore deposits, acid mine water and soil. It palys important roles in bioleaching, coal desulfurization and sulfur-containing waste water treatment. Under acidic conditions, it can oxidize Fe2+, sulfur or reduced sulfur compounds, and obtain energy from oxidation of the inorganic compounds. Ferric iron produced from ferrous oxidation is a kind of powerful oxidant, which can oxidize insoluble metallic sulfides to soluble form in acidic media. Therefore, ferrous oxidation activity of A. ferrooxidans is closely related with bioleaching efficiency.In practical applications, the defects of slow growth speed, long proliferation time, low cell yield of A. ferrooxidans result in low efficiency. Therefore, by using genetic technique to improve its growth and iron oxidation speed is imperative.In this thesis, ferrous oxidation related genes——cox, cup and iro were cloned and identified, ligated into extensive host plasmids pJRD215 or pMSD2. Sucecefully, three transmissible vectors——pTCOX, pTCUP and pTIRO were constructed, which were then transferred into A. ferrooxidans by conjugation. Conjugation frequencies and plasmids stability were evaluated. After confirmation, several tests were conducted with these constructed strains——A.ferrooxidans(pTCOX), A.ferrooxidans(pTCUP) and A.ferro-xidans(pTIRO). The results show that A. ferrooxidans(pTCOX) has faster iron oxidation rate, rapid increase of redox potential, slightly faster growth rate and higher leaching rate.Then real-time PCR was proceeded to detection gene expression levels in rus operon of A. ferrooxidans(pTCOX).CoxB, Cox A and cyc2 were up-regulated by 2.1,3.9 and 5.9 times compared with wild type control.