| Acidithiobacillus ferrooxidans(abbreviation:A.f) is one of the bacteria that are applied in bioleaching industry.It can oxidize ferrous,sulfure and partially oxidized sulfur compounds.A.f is the model species of bioleaching bacteria,and many researches about the mechanism of ferrous oxidation have been carried out,and several electron carriers were discovered,for example:Iro,Rus,Cytochrome C oxidase,Cytochrome C,bcl complex and so on.Several electron transfer chains of ferrous oxidation were suggested,but none of them was testified.The research progresses on the mechanism of sulfure oxidation is slow,some researchers discovered that sulfure oxidation is related to ferrous oxidation,ferric can play as an electron acceptor to oxidize sulfure to sulfite,sulfite would be oxidized to sulfate. Elemental sulfure can be used as sole energy source when ferrous and ferric ions are absent,which suggest that there is another sulfure oxidation pathway.There are several proteins related to sulfure oxidation and transference were discovered in A.f, but the actual role of the proteins in A.f cells are not clear.Many kinds of ions dissolved into the environments in the process of bioleaching, the high density ions can inhibit the bioleaching ability.There are three hypotheses to explain the resistance to high density ions.Some researchers thought that the gene mutants enhance the resistance under the choice of the harsh environment,but it is not proved yet.The second idea showed that the enhancement of ions resistance is related to the mutants caused by the random insertion of IS in the genome of A.f.The third hypothesis indicate that the resistance is related to the plasmids reside in A.f,but it is still unclear.The researches on the mechanisms of ferrous,sulfure oxidation and the resistance to high density ions are significant to the application of A.f in bioleaching industry.The thesis main works include two parts 1.Comparative Proteomics analysis of A.f that using ferrous or sulfure as sole energy sourceBy two-dimensional electrophoresis and MALDI-TOF MS,we identified 24 spots of differential-expressed proteins,16 spots of them are upregulated,8 spots are downregulated in the sulfure oxidation process.The transcription patterns of the genes were detected by Northen blot.The results show that the 24 genes are differently transcripted in RNA levels,.The differential-expressed proteins include:Pyridine nucleotide-disulfide oxidoreductase,thioredoxin-disulfide reductase(trxB),heterodisulfide reductase subunit B,Hsp20 family,sulfite reductase(NADPH) flavoprotein alpha component(cysJ),cysteine desulfurase IscS(iscS-3),AhpC-TSA family-glutaredoxin domain protein,antioxidant AhpC-Tsa family,glutamyl-tRNA reductase,fructose-bisphosphate aldolase,putative,6-phosphogluconate dehydrogenase family protein,transaldolase,and several kinds of unkown proteins and hypothetical proteins.We can deduced that there are several metabolism pathways take part in the oxidation of ferrous,sulfure and the adaptation to the growing circumstances from the results.2.Comparative Proteomics analysis of A.f that growing in normal and high density KCl ions circumstancesWe successfully identified 8 kinds of differential-expressed proteins by two-dimentional electrophoresis and MALDI—TOF—TOF,4 spots of them are upregulated,and 4 spots are downregulated in the circumstances of high density KCl ions.We detected the genes transcription patterns by Northen blot.The results show that 7 genes are differently transcripted in RNA levels,but the transcriptional differences of spot 4(methionine aminopeptidase) is not obvious.The differential-expressed proteins include:GDP-mannose 4,6-dehydratase(gmd-1),ribose 5-phosphate isomerase A(rpiA),ribose-phosphate pyrophosphokinase(prsA),phosphoglycolate phosphatase(gph-2),ATP synthase F1 delta subunit(atpH),ATP synthase F1 beta subunit(atpD),methionine aminopeptidase,a conserved hypothetical protein.The metabolism pathways GDP-mannose 4,6-dehydratase(gmd-1) and ribose 5-phosphate isomerase A(rpiA) may involve in the synthesis of polysaccharide.We deduce that the production of polysaccharide may take part in the resistance to the high density KCl ions.
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