Comparison Research Of Physiological Features Of Acidithiobacillus Ferrooxidans And The Mechanism Of Environmental Adaptability Of Sulfobacillus Acidophilus

Acidithiobacillus ferrooxidans (A.f for short) is a chemolithautotrophic bacterium which can obtain energy from the oxidation of ferrous ion,elemental sulfur or partially oxidized sulfur compounds.This ability makes it applicable to recover metal such as copper,gold and uranium.Sulfobacillus acidophilus (S.a for short) is a kind of moderate-thermophilic bacterium. It can obtain energy from ferrous ion,elemental sulfur and sulfur compounds when culture as chemolithautotrophic bacterium, and it also can grow heterotrophic and mixotrophic by using yeast extract. People began to do research about S.a later and less than A.f, but for S.a can adapt the environment better, endure higher temperature, more kinds of trophic types than A.f, all of these made it more useful in bioleaching. To know more of the physiologic characterictics, mechanism of bioleaching and environmental adaptability, and help to isolate more active strain in bioleaching, we did some research about these two bacteria.1,In this research,Four strains of Acidithiobacillus ferrooxidans (A. f for short), A.f.1, A.f.2, A.f.3 and A.f.c, were isolated from samples with different geological sources using a 9K medium. These four isolates were identified as Acidithiobacillus ferrooxidans by phenotypic and 16S rDNA sequence analyses. All four isolates were able to use ferrous (Fe2+), elemental sulfur (S0) or pyrite as a sole energy source, but they showed differences in pH optima and range of activity, optimum temperature of activity, resistance to chloride (KCl) and heavy metal ions, and oxidation rates of Fe2+, S0 and pyrite. A.f.3 was the most active strain when using Fe2+ as the energy source, while A.f.c grew best using pyrite as the energy source. A.f.2 appeared to differ from the other three strains in substrate utilization, as it oxidizes S0 and pyrite more effectively than Fe2+. RAPD analysis of genomic DNA from these isolates showed that banding profiles of their genomic DNA exhibited some differences, and the genomic banding profile of A.f.2 was significantly different from that of others. To get an insight into the molecular biology of the process of the energy production of these strains, several genes involved in the iron respiratory chain were cloned and sequenced, including Fe2+ oxidase (iro), rusticyanin (rus) and subunit III of aa3- type cytochrome oxidase (coxC) genes. The results revealed that the iro gene can be cloned from all of the four strains and the nucleotide sequences were shown to be completely identical in each. However, rus and coxC genes could be amplified only from A.f.1, A.f.3, and A.f.c, not from A.f.2. These results suggested that the phenotypic differences of the four strains of A.f from different sites correlated with their genetic polymorphism, which may result from the different environment in which they lived, and that the strain A.f.2 was phenotypically and genetically significantly different from the other three strains.2,Sulfobacillus acidophilus was isolated from a sample which came from Pacific ocean. The optima pH, temperature and energy source were found out by grads experiments. This strains of S.a was most active at temperature between 45 to 50℃, pH around 1.8. The concentration of inorganic compounds was consistent as the 882 medium in DSMZ. When cultivated as an autotrophic bacterium, it was most active at the concentration of ferrous was 13.9g/L or elemental sulfur was 10g/L. And when it was cultivated as heterotrophic or mixotrophic bacterium, it was most active at the concentration of yeast extract was 0.2g/L.3,To find out the mechanism of the environmental adaptability and different mechanism of metabolize, Differential Displayed reverse transcriptase-PCR (DDRT-PCR) and Random Arbitrarily Primed PCR (RAP-PCR) were done about Sulfobacillus acidophilus between different temperature and different energy source. 91 differential cDNA fragments in total were isolated, including 36 fragments were about temperature and 55 fragments were about energy source. 45 different cDNAs were analyzed by Northern blot, among which 30 were confirmed to be differentially expressed at the transcriptional levels. These differentially expressed genes reflected a profile of organismal adaptation, and were involved in many physiological processes such as cell membrane alterations, regulatory adaptive response and metabolism; most of them have never been reported before. This study provides a better understanding of the adaptability to environment and different mechanism of metabolize about this strain of S.a.