Investigation On Microbial Typical Function Groups Of Acid Mine Environment In Shizishan Sulfide Mine, Tongling, Anhui Province And Identification And Characterization Of Isolated Strain NJU-t1

Investigation on typical microbial function groups of acid mine environment in Shizishan sulfide mine, Tongling, Anhui Province and identification and characterization of isolated strain NJU-T1were taken in this paper. Typical microbial function groups were investigated from the acid mine drainage, sediments and tailings samples that collected in acid mine environment with microbial cultured and uncultured techniques. Forteen bacteria strains were isolated with the overlay technique with four selective media YE, Feo, FeSo and FeTo. The16S rRNA gene sequences were amplified from total DNA of bacteria strains, then sequenced and analyzed by MEGA5.0. The phylogenetic tree analysis with16S rRNA gene sequences of isolated bacteria strains was carried out. Results showed that all of isolated bacteria strains were belong to Acidithiobacillus, Acidosphaera, Acidocella, Acidiphilium, and can be divided into four microbial communities:heterotrophic acidophiles, autotrophic acidophiles, moderately acidophilic iron-oxidizing bacteria, moderately acidophilic iron-reducing bacteria. The function of heterotrophic acidophiles was dissimilatory ferric iron reduction and creating an oligotrophic environment. The acidophilic heterotrophic bacteria of acid mine drainage were related to the reduction of trivalent iron and restoration and maintain the oligotrophic state. The autotrophic bacteria is producer in acidic mine drainage, which related to the oxidation of iron, sulfur, which oxidized low valence sulfur in sulfide minerals to sulfate, producing energy to fix carbon dioxide to organic matter, and producing substances such as growth factor for the growth of other microorganisms of the acid mine drainage. Through the synergy of acidophilic iron-reducing bacteria and iron oxidizing bacteria, the dynamic balance of ferrous iron and ferric iron, iron in acid mine water and sediments could be realized, which allowing the acid mine water into a relatively stable ecosystem.Strain NJU-T1, isolated by FeTo Overlay medium from tailings in the Shizishan acid mine environment, was subjected to a taxonomic study using a polyphasic approach. Colonies were white, nearly round, neat edge intact shell, with the dry surface. Cells were single, non-spore forming, rod-shaped, Gram-negative, bacterial size (lengthxwidth):1.0-3.0μm×0.2-0.3∴m, motile by gliding. Strains NJU-T1could not grow under the anaerobic condition. Strain NJU-T1could grow at0-3%salinity and the optimum growth was at0%. The pH range was2.0-8.0, the optimum was4.5to5.0; The temperature range was5-40℃, the optimum was30℃. Strain NJU-T1could grow on FeTo, FeSo, Feo medium, but could not grow in MA, NA and TSA media. Fexirubin pigment was not detected in Strain NJU-T1cell. Arabinose and salicin could be utilized as carbon source, but could not use glucose, sucrose, galactose, fructose, ribose, rhamnose, mannitol, mannose, sorbitol, maltose, xylose, lactose, etc. and could not utilize nitrate and nitrite, could not make the gelatin liquefied, non-amylase activity, non-urease activity. The main fatty acid composition was18:1w7c,16:1w7c/16:1w6c, of16:0,14:03OH/16:1iso I and12:0. Menaquinone MK-7was the major quinine in strain NJU-T1. Phylogenetic analysis based on the16S rRNA gene sequence showed that strain NJU-Tl belonged to the genus Acidithiobacillus, with Acidithiobacillus caldus, Thermophilic bacterium (95%similarity) as its closest relatives. Therefore, it is proposed that strain NJU-T1represents a novel species of typical genus Acidithiobacillus.The characteristics of strain NJU-T1ware studied. It is found that NJU-T1could reduce ferric iron under aerobic conditions with plate and liquid cultural tests. The pH range for growth was pH2.0-6.0, with optimum growth at pH4.5, optimum growth temperature at30℃and optimum ferric iron concentration at5mmol/l. It was inferred that the reduction sites may be located on the cell outer membrane. AMD and tailings were controlled by the dynamic balance between the microbial functional groups and surroundings. The NJU-T1reduced ferric to ferrous iron, which provided initial energy to ferrous-oxidizing bacteria and maintained the Fe recycle and stability of acid mine environment.