Isolation And Identification Of Autotrophic And Heterotrophic Bacterium And Study On Their Bioleaching And Metabolic Thermogenesis

In the acid mine drainage(AMD),there are many kinds of Autotrophic and Heterotrophic bacterium,which can be used in bioleaching.This research worked on the isolation,physiological and bioleaching characterization of Leptospirillum ferriphilum and Acidiphilium sp.and the metabolic thermogenesis of the bacteria under different conditionsAn Acidiphilium strain DX-A was isolated from acid mine drainage of Dexing mine,Jiangxi province,China.The cell of DX-A strain is rod-shaped in(0.45～0.55)μm×(1.1～2.1)μm and Gram negative.The optimum growth temperature is 30℃,and the optimum growth pH is 3.5. It can grow facultative heterotrophically by using glucose,lactose,FeCl₃ and sulfide mineral as sole energy sources,but can not grow with FeSO₄. A phylogenetic tree was constructed with the published 16S rRNA gene sequences of the relative bacteria species.In the phylogenetic tree,the DX-Astrain has the closest relative to the Acidiphilium sp.PK46 (AY765995) with 99%sequence similarity.Leptospirillum ferriphilum DX-B was also isolated from acid mine drainage of Dexing mine,Jiangxi province.The cell of DX-B strain are small curve rod-shaped or helical-shaped,the size of which measured was about 0.32 to 0.50μm wide and 0.78 tol.25μm long.The optimum growth temperature is 40℃,and the optimum growth pH is 1.7.The bioleaching experiment of two kind of sulfide mineral in shake flasks revealed that the Acidiphilium sp.DX-A and Leptospirillum ferriphilum DX-B had little efficiency of leaching sulfide mineral by themselves but when coupled with each other it can increase the pyrite and marmatite leaching efficiency.The reason was the combination of the acidophilic heterotrophic Acidiphilium sp.and acidophilic autotrophilic Leptospirillumferriphilum in bioleaching pyrite and marmatitemetabolic thermogenesis of the bacteria under different conditions(different concentration of the bacteria,different initial pH values and different mediums)were studied using microcalorimetry.The fundamental growth thermograms of bacteria can be determined by using the mircocalorimetric method.These perfect thermogram curves reflect the changes of bacterial growth patterns(including the lag phase of growth,log growth,stationary phase and the decline phase of growth).For strain DX-A,pH is 3.0,concentration of the bacteria is 1.8x10⁸ is the best condition of growth thermograms.The bacterium cultured in different mediums creates different growth thermograms,the one who creates the biggest heat of reaction is 9k+glucose.For A.ferrooxidans ATCC23270,the best conditions for the metabolic thermogenesis is pH=2.0 or 2.3,concentration of bacteria is 3.0×10⁸cell/ mL,and cultured in 2039+ FeSO₄ medium.